@article {137, title = {Method and software for the determination and time profile of an insulin dosis}, number = {AR 15015601}, year = {Submitted}, month = {01/2015}, publisher = {CONICET(AR), UNLP(AR), UdG(ES)}, type = {Application}, address = {Argentina(AR), Spain (ES)}, abstract = {

Method and software for the determination and time profile of an insulin dosis to be infused to an user. The method comprises the estimation, using an algorithm executed in a processor, of an insulin on board value, or IOB, indicative of a level of residual insulin yet active in the body of a user after being delivered to him; and the calculation, using an algorithm executed in a processor, of an insulin dosis to be delivered in successive pump instants by an insulin pump, during a given time interval, so that the estimated IOB value tracks at least one\  prescribed IOB profile, independently of boluses or correction boluses previously infused to the used.

}, author = {De Battista, Hern{\'a}n and Garelli, Fabricio and Le{\'o}n, Fabi{\'a}n and Veh{\'\i}, Josep} } @article {336, title = {Online Classification of Unstructured Free-Living Exercise Sessions in People with Type 1 Diabetes}, journal = {Diabetes Technology \& Therapeutics}, volume = {26}, year = {2024}, pages = {709-719}, abstract = {

Background: Managing exercise in type 1 diabetes is challenging, in part, because different types of exercises can have diverging effects on glycemia. The aim of this work was to develop a classification model that can classify an exercise event (structured or unstructured) as aerobic, interval, or resistance for the purpose of incorporation into an automated insulin delivery (AID) system. Methods: A long short-term memory network model was developed with real-world data from 30-min structured sessions of at-home exercise (aerobic, resistance, or mixed) using triaxial accelerometer, heart rate, and activity duration information. The detection algorithm was used to classify 15 common free-living and unstructured activities and relate each to exercise-associated change in glucose. Results: A total of 1610 structured exercise sessions were used to train, validate, and test the model. The accuracy for the structured exercise sessions in the testing set was 72\% for aerobic, 65\% for interval, and 77\% for resistance. In addition, we tested the classifier on 3328 unstructured sessions. We validated the session-associated change in glucose against the expected change during exercise for each type. Mean and standard deviation of the change in glucose of -20.8 (40.3) mg/dL were achieved for sessions classified as aerobic, -16.2 (39.0) mg/dL for sessions classified as interval, and -11.6 (38.8) mg/dL for sessions classified as resistance. Conclusions: The proposed algorithm reliably identified physical activity associated with expected change in glucose, which could be integrated into an AID system to manage the exercise disturbance in glycemia according to the predicted class.

}, doi = {10.1089/dia.2023.0528}, url = {https://doi.org/10.1089/dia.2023.0528}, author = {Fushimi, Emilia and Aiello, Eleonora M. and Cho, Sunghyun and Riddell, Michael C. and Gal, Robin L. and Martin, Corby K. and Patton, Susana R. and Rickels, Michael R. and Doyle, Francis J.} } @article {333, title = {Active Power Control on wind turbines: impact on mechanical loads}, journal = {IEEE Latin America Transactions}, volume = {21}, year = {2023}, month = {Sep.}, pages = {984{\textendash}990}, abstract = {

This work focuses on the evaluation of how Active Power Control (APC) impacts the mechanical loads of a utility size Wind Turbine (WT). Two APC strategies, each with four levels of power reserve, are considered and compared. The assessment is numerically performed over the 5 MW WT benchmark model. Fatigue analysis is carried out under realistic wind profiles and following IEC 61400-1 standard. Extreme load analysis is performed as well, with extreme wind conditions as defined in the standard, and with a statistical load extrapolation from normal wind conditions. The assessment is repeated with both a Linear Parameter-Varying controller and a gain scheduling Proportional Integral controller comprising 3225 simulations. Interesting results are obtained about how APC affects mechanical loads, and how this impact changes according to the control strategy applied. For instance, for some combination of controller
scheme and APC strategy, fatigue loading is reduced with respect to maximum power tracking without increasing extreme loads. These results lead to the conclusion that fatigue load can be improved by unevenly distributing power reserve among wind turbines across the wind farm.

}, url = {https://latamt.ieeer9.org/index.php/transactions/article/view/7817}, author = {Ib{\'a}{\~n}ez, Bernab{\'e} and Inthamoussou, Fernando A. and De Battista, Hern{\'a}n} } @article {332, title = {Auto adaptation of closed-loop insulin delivery system using continuous reward functions and incremental discretization}, journal = {Computer Methods in Biomechanics and Biomedical Engineering}, year = {2023}, pages = {1-12}, abstract = {

Several closed or hybrid loop controllers for Blood Glucose (BG) regulation, which are also known as Artificial Pancreas (AP) Systems or Automated Insulin Delivery systems (AIDs), are in development worldwide. Most AIDs are designed and evaluated for short-term performance, with a particular emphasis on the post-meal period. However, if controllers are not adapted properly to account for variations in physiology that affect Insulin Sensitivity (IS), the AIDs may perform inadequately. In this work, the performance of two Reinforcement Learning (RL) agents trained under both piecewise and continuous reward functions is evaluated in-silico for long-term adaptation of a Fully Automated Insulin Delivery (fAID) system. An automatic adaptive discretization scheme that expands the state space as needed is also implemented to avoid disproportionate state space exploration. The proposed agents are evaluated for long-term adaptation of the Automatic Regulation of Glucose (ARG) algorithm, considering variations in IS. Results show that both RL agents have improved performance compared to a rule-based decision-making approach and the baseline controller for the majority of the adult population. Moreover, the use of a continuous shaped reward function proves to enhance the performance of the agents further than a piecewise one.

}, doi = {10.1080/10255842.2023.2241945}, url = {https://doi.org/10.1080/10255842.2023.2241945}, author = {Serafini, Mar{\'\i}a Cecilia and Rosales, Nicol{\'a}s and Garelli, Fabricio} } @article {334, title = {Computational assessment of lipid production in Rhodosporidium toruloides~in two-stage and one-stage batch bioprocesses}, journal = {Biotechnology and Bioengineering}, volume = {n/a}, year = {2023}, abstract = {

Oleaginous yeasts are promising platforms for microbial lipids production as a renewable and sustainable alternative to vegetable oils in biodiesel production. In this paper, a thorough in silico assessment of lipid production in batch cultivation by Rhodosporidium toruloides\ was developed. By means of dynamic flux balance analysis, the traditional two-stage bioprocess (TSB) performed by the native strain was contrasted with one-stage bioprocess (OSB) using four designed strains obtained by gene knockout strategies. Lipid titer, yield, content, and productivity were analyzed at different initial C/N ratios as relevant performance indicators used in bioprocesses. By weighting these indicators, a global lipid efficiency metric\ (GLEM) was defined to consider different scenarios. Under simulated conditions, designed strains for lipid overproduction in OSB outperformed the TSB in terms of lipid title (up to threefold), lipid yield (up to 2.4-fold), lipid content (up to 2.8-fold, with a maximum of 76\%), and productivity (up to 1.3-fold), depending on C/N ratios. Using these efficiency parameters and the proposed GLEM, the process of selecting the most suitable candidates for lipid production could be carried out before experimental assays. This methodology holds the potential to be extended to other oleaginous microorganisms and diverse strain design techniques.

}, doi = {10.1002/bit.28579}, author = {Casta{\~n}eda, Mar{\'\i}a Teresita and Nu{\~n}ez, Sebasti{\'a}n and Jamilis, Mart{\'\i}n and De Battista, Hern{\'a}n} } @article {328, title = {Online adjustable linear parameter-varying controller for artificial pancreas systems}, journal = {Biomedical Signal Processing and Control}, volume = {86}, year = {2023}, pages = {105164}, abstract = {

The purpose of this article is to present a non-hybrid fully closed-loop controller for the Artificial Pancreas (AP) problem focused on long-term clinical trials and home-use applications. It includes physical activity (PA) and unannounced meals. The controller is based on a robust gain-scheduled algorithm with a Linear Parameter-Varying (LPV) structure. It takes into account the time-varying dynamics of the problem by adapting itself in real-time according to measured glucose levels, and allows online fine-tuning during tests and periodic evaluations without the need of a controller redesign. The proposed fully parameterized LPV control adds several features to our previous results, accounts for the main perturbations of the AP problem and simplifies its implementation. To help in the parameter fine-tuning, a methodology based on clinical information is proposed. In-silico tests show that the achieved performance is similar or better than our previous Automatic Regulation of Glucose (ARG) algorithm, tested in two clinical trials, with the addition of the features mentioned before.

}, keywords = {Artificial pancreas, Diabetes type 1, insulin-on-board, LPV control}, issn = {1746-8094}, doi = {https://doi.org/10.1016/j.bspc.2023.105164}, url = {https://www.sciencedirect.com/science/article/pii/S1746809423005979}, author = {Bianchi, Fernando D. and S{\'a}nchez-Pe{\~n}a, Ricardo S. and Garelli, Fabricio} } @article {329, title = {Sizing and analytical optimization of an alkaline water electrolyzer powered by a grid-assisted wind turbine to minimize grid power exchange}, journal = {Renewable Energy}, volume = {216}, year = {2023}, pages = {118990}, abstract = {

This work aims to contribute to the efforts made from various disciplines to optimize the hydrogen production from renewable energy sources. The problem is posed from the perspective of the design of an alkaline water electrolyzer powered by wind energy with the assistance of the electric grid. The novelty lies in considering the resource variability in the electrolyzer sizing according to the turbine location and the operating conditions ensured by the grid. Three variable operation modes for grid assistance depending on the available wind are proposed. For each one, the nominal electrolyzer power that minimizes the annual power exchanged with the grid {\textendash} and therefore the related carbon dioxide emissions {\textendash} is found. The optimization results are presented in several curves that have the advantage of helping to compare the operation modes for different resource conditions characterized by the Weibull distribution. They helped to conclude that the variable operation modes are optimized with higher nominal electrolyzer powers than with the fixed mode for the same nominal turbine power.

}, keywords = {Alkaline electrolyzer, Optimal design, Renewable hydrogen, Variable operation, Weibull distribution}, issn = {0960-1481}, doi = {https://doi.org/10.1016/j.renene.2023.118990}, url = {https://authors.elsevier.com/a/1hSkS3QJ-dpR-0}, author = {Gallo, Mar{\'\i}a A. and Garc{\'\i}a-Cl{\'u}a, Jos{\'e} G.} } @article {324, title = {Control no-h{\'\i}brido de glucemia ensayado en pacientes ambulatorios con Diabetes Tipo 1}, journal = {Revista Iberoamericana de Autom{\'a}tica e Inform{\'a}tica industrial}, year = {2022}, month = {abr.}, abstract = {

En este trabajo se presenta la experiencia argentina en el problema de regulaci{\'o}n de los niveles de glucosa en sangre para pacientes con Diabetes Mellitus Tipo 1 (insulino-dependientes), denominado P{\'a}ncreas Artificial. El grupo de trabajo ha realizado 3 pruebas cl{\'\i}nicas, las primeras en Latinoam{\'e}rica. Las dos primeras fueron concretadas en 2016 y 2017, ambas en el Hospital Italiano con 5 pacientes adultos durante 36 hs. En la segunda de ellas se utiliz{\'o} un nuevo algoritmo de control de lazo cerrado puro (sin bolo prandial), llamado ARG (Automatic Regulation of Glucose) y basado en un control LQG conmutado en combinaci{\'o}n con la capa de seguridad SAFE (Safety Auxiliary Feedback Element), desarrollado por investigadores de nuestro equipo. Este a{\~n}o se llev{\'o} a cabo la primera prueba ambulatoria, realizada en un hotel con 5 pacientes durante 6 d{\'\i}as en marzo de 2021. En esta tercera prueba adem{\'a}s, se utiliz{\'o} una plataforma desarrollada por la Universidad Nacional de La Plata (UNLP), denominada InsuMate. {\'E}sta conecta el celular con la bomba de insulina y el monitor de glucosa, aloja el algoritmo de control y permite el monitoreo remoto de m{\'u}ltiples pacientes. Los resultados obtenidos sugieren que el uso del algoritmo ARG en forma ambulatoria es factible, seguro y eficaz en comparaci{\'o}n con la terapia usual. Asimismo, la plataforma InsuMate result{\'o} ser intuitiva y sencilla para los usuarios, tanto m{\'e}dicos como pacientes participantes del ensayo, logrando un tiempo de funcionamiento del lazo cerrado superior al 95 \%

}, doi = {10.4995/riai.2022.16652}, url = {https://polipapers.upv.es/index.php/RIAI/article/view/16652}, author = {Garelli, Fabricio and Fushimi, Emilia and Rosales, Nicol{\'a}s and Arambarri, Delfina and Serafini, Mar{\'\i}a Cecilia and De Battista, Hern{\'a}n and Grosembacher, Luis and S{\'a}nchez-Pe{\~n}a, Ricardo Salvador} } @article {322, title = {A Dual-Hormone Multicontroller for Artificial Pancreas Systems}, journal = {IEEE Journal of Biomedical and Health Informatics}, year = {2022}, pages = {1-8}, abstract = {

Artificial pancreas (AP) algorithms can be divided into single-hormone (SH) and dual-hormone (DH). SH algorithms regulate glycemia using insulin as their control input. On the other hand, DH algorithms also use glucagon to counteract insulin. While SH-AP systems are already commercially available, DH-AP systems are still in an earlier research phase. DH-AP systems have been questioned since the added complexity of glucagon infusion does not always guarantee hypoglycemia prevention and might significantly raise insulin delivery. In this work, a DH multicontroller is proposed based on a SH linear quadratic gaussian (LQG) algorithm with an additional LQG controller to deliver glucagon. This strategy has a switched structure that allows activating one of the following three controllers when necessary: a conservative insulin LQG controller to modulate basal delivery ($K_{1}$), an aggressive insulin LQG controller to counteract meals ($K_{2}$), or a glucagon LQG controller to avoid imminent hypoglycemia ($K_{3}$). Here, an in silico study of the benefits of incorporating controller $K_{3}$ is carried out. Intra-patient variability and mixed meals are considered. Results indicate that the proposed switched, dual-hormone strategy yields to a reduction in hypoglycemia without increasing hyperglycemia, with no significant rise in insulin delivery.

}, issn = {2168-2208}, doi = {10.1109/JBHI.2022.3182581}, author = {Fushimi, Emilia and De Battista, Hern{\'a}n and Garelli, Fabricio} } @article {323, title = {First Outpatient Clinical Trial of a Full Closed-Loop Artificial Pancreas System in South America}, journal = {Journal of Diabetes Science and Technology}, year = {2022}, pages = {19322968221096162}, abstract = {

Background:The first two studies of an artificial pancreas (AP) system carried out in Latin America took place in 2016 (phase 1) and 2017 (phase 2). They evaluated a hybrid algorithm from the University of Virginia (UVA) and the automatic regulation of glucose (ARG) algorithm in an inpatient setting using an AP platform developed by the UVA. The ARG algorithm does not require carbohydrate (CHO) counting and does not deliver meal priming insulin boluses. Here, the first outpatient trial of the ARG algorithm using an own AP platform and doubling the duration of previous phases is presented.Method:Phase 3 involved the evaluation of the ARG algorithm in five adult participants (n = 5) during 72 hours of closed-loop (CL) and 72 hours of open-loop (OL) control in an outpatient setting. This trial was performed with an own AP and remote monitoring platform developed from open-source resources, called InsuMate. The meals tested ranged its CHO content from 38 to 120 g and included challenging meals like pasta. Also, the participants performed mild exercise (3-5 km walks) daily. The clinical trial is registered in ClinicalTrials.gov with identifier: NCT04793165.Results:The ARG algorithm showed an improvement in the time in hyperglycemia (52.2\% [16.3\%] OL vs 48.0\% [15.4\%] CL), time in range (46.9\% [15.6\%] OL vs 50.9\% [14.4\%] CL), and mean glucose (188.9 [25.5] mg/dl OL vs 186.2 [24.7] mg/dl CL) compared with the OL therapy. No severe hyperglycemia or hypoglycemia episodes occurred during the trial. The InsuMate platform achieved an average of more than 95\% of the time in CL.Conclusion:The results obtained demonstrated the feasibility of outpatient full CL regulation of glucose levels involving the ARG algorithm and the InsuMate platform.

}, doi = {10.1177/19322968221096162}, url = {https://doi.org/10.1177/19322968221096162}, author = {Garelli, Fabricio and Fushimi, Emilia and Rosales, Nicol{\'a}s and Arambarri, Delfina and Mendoza, Leandro and Serafini, Mar{\'\i}a Cecilia and Moscoso-V{\'a}squez, Marcela and Stasi, Marianela and Duette, Patricia and Garc{\'\i}a-Arabehety, Julia and Giunta, Javier and De Battista, Hern{\'a}n and S{\'a}nchez-Pe{\~n}a, Ricardo and Grosembacher, Luis} } @article {315, title = {Hypoglycemia prevention: PID-type controller adaptation for glucose rate limiting in Artificial Pancreas System}, journal = {Biomedical Signal Processing and Control}, volume = {71}, year = {2022}, month = {09/2021}, pages = {103106}, abstract = {

Within the development of closed-loop glucose controllers, one of the major risks is insulin induced hypoglycemia due to controller overreaction. In this paper, a novel strategy based on sliding mode control is proposed in order to reduce hypoglycemic events in glycemic closed-loop control via the subcutaneous route. This is achieved with the use of a supervisory layer over the main controller, called the GSAFE algorithm, which is in charge of attenuating excessive glycemic rates of change. When the rate of change of the predicted glycemic level obtained by a Kalman Filter falls below a certain predefined threshold, the GSAFE layer modulates the output of the controller so that the insulin infusion does not cause the glycemic rate of change to exceed a preestablished constraint. In this manner, the insulin delivered is not only suspended if it is necessary but it is also adapted by a time-varying gain. In-silico tests with and without the GSAFE layer were run in order to asses the proposal performance. For a cohort of n = 30 subjects the GSAFE layer reduced the time spent in hypoglycemia of a PD type controller in both nominal (0.54 (2.98) vs. 1.81 (3.17), ρ=0.048) and variability single-day scenarios (0.33 (1.79) vs. 2.23 (5.61), ρ\<0.01). Also an aggressive tuning of the main controller was considered and the proposed methodology reduced the time spent in hypoglycemia in both nominal (3 (7.58) vs. 7.69 (10.34), ρ\<0.01) and variability scenarios (2.96 (6.65) vs. 6.22 (8.94), ρ\<0.01). This proposal can be applied to any control structure. Results are promising and future clinical tests are expected.

}, doi = {10.1016/j.bspc.2021.103106}, author = {Rosales, Nicol{\'a}s and De Battista, Hern{\'a}n and Garelli, Fabricio} } @article {325, title = {Practical constraint definition in safety schemes for artificial pancreas systems}, journal = {The International Journal of Artificial Organs}, volume = {45}, year = {2022}, pages = {535-542}, abstract = {

Introduction:Artificial pancreas systems usually define an insulin-on-board constraint (IOB{\textasciimacron}) for safety schemes to limit the insulin infusion and avoid hypoglycemia during the closed-loop performance. Several methods have been proposed with impractical considerations requiring information from the prandial events or complex procedures for ambulatory use.Methods:This paper presents a simple method that consists of two novel rules that allow finding an IOB{\textasciimacron} based only on common clinical parameters that do not require patient intervention. The method robustness was evaluated using a control system coupled to a safety layer under demanding scenarios implemented on the FDA-approved simulator for preclinical studies.Results:The method maintains a safe performance, even in the face of interpatient variability, hybrid and fully automatic implementations of an artificial pancreas system, and uncertain settings. Both proposed rules work as effectively or even better and without the patient intervention than other methods that have already been clinically validated.Conclusion:This method can be used to define a constant IOB{\textasciimacron} that ensures performance and safety of the control system, even under scenarios with incorrect clinical data. Unlike other methods, this method only requires reliable information that is easily obtained from the patient, such as their total daily dose of insulin or body mass.

}, doi = {10.1177/03913988221095586}, url = {https://doi.org/10.1177/03913988221095586}, author = {Rodr{\'\i}guez-Sarmiento, David L and Le{\'o}n-Vargas, Fabi{\'a}n and Garelli, Fabricio} } @article {316, title = {Extended SEIR Model for Health Policies Assessment Against the COVID-19 Pandemic: the Case of Argentina}, journal = {Journal of Healthcare Informatics Research}, year = {2021}, month = {12/2021}, abstract = {

This work presents an extended and age-band compartmentalised SEIR model that allows describing the spread evolution of SARS-CoV-2 and evaluating the effect of different detection rates, vaccination strategies or immunity periods. The model splits up the population into fifteen age groups of 5 years each, linked through a statistical interaction matrix that includes seventeen health states within each age group. An age-dependent transmission rate takes into account infectious between the groups as well the effect of interventions such as quarantines and mobility restrictions. Further, the proposal includes a nonlinear switched controller for model tuning purposes guarantying a simple and fast adjusting process. To illustrate the model potentials, the particular case of COVID-19 evolution in Argentina is analysed by simulation of three scenarios: (i) different detection levels combined with mobility restrictions, (ii) vaccination campaigns with re-opening of activities and (iii) vaccination campaigns with possible reinfections. The results exhibit how the model can aid the authorities in the decision making process.

}, issn = {2509-498X}, doi = {10.1007/s41666-021-00110-x}, author = {Inthamoussou, Fernando A. and Valenciaga, Fernando and Nu{\~n}ez, Sebasti{\'a}n and Garelli, Fabricio} } @article {314, title = {A fast and robust closed-loop photovoltaic MPPT approach based on sliding mode techniques}, journal = {Sustainable Energy Technologies and Assessments}, volume = {47}, year = {2021}, pages = {101499}, abstract = {

This article presents a closed-loop Maximum Power Point Tracking (MPPT) method for a photovoltaic (PV) system that includes a PV array, a DC-DC converter and a DC bus. The proposal consists of a controller and two observers developed into the sliding mode (SM) theoretical framework. The converter switching signal is driven by an Integral First-Order Sliding Mode (IFOSM) controller whose input corresponds to the PV power gradient estimation. This estimation is obtained through a pair of Second Order Sliding Mode Observers (SOSM). The first one corresponds to a Levant{\textquoteright}s differentiator which estimates the first-time derivative of the PV voltage and feds a specific SOSM which delivers the PV power gradient estimation. These kinds of observers converge in finite time even in the presence of unmodeled dynamics and external perturbations. The proposed structure permits to synthesise a whole MPPT closed-loop system with a fast-tracking dynamics, a moderate computational burden and a reduced hardware cost, requiring only two variable measurements. This approach, simplifies the controller design and the system start-up, which does not need any specific initial conditions to be started from. The system performance is evaluated using representative computer simulations with standardised radiation and temperature profiles and corroborated through experimental tests. Finally, the proposal capabilities to work under partial shading conditions are also evaluated.

}, keywords = {Maximum power extraction, MPPT, Photovoltaic energy, Sliding modes}, issn = {2213-1388}, doi = {https://doi.org/10.1016/j.seta.2021.101499}, url = {https://www.sciencedirect.com/science/article/pii/S2213138821005105}, author = {Inthamoussou, Fernando A. and Valenciaga, Fernando} } @article {313, title = {Non-pharmaceutical intervention to reduce COVID-19 impact in Argentina}, journal = {ISA Transactions}, year = {2021}, abstract = {

This work is focused on the multilevel control of the population confinement in the city of Buenos Aires and its surroundings due to the pandemic generated by the COVID-19 outbreak. The model used here is known as SEIRD and two objectives are sought: a time-varying identification of the infection rate and the inclusion of a controller. A control differential equation has been added to regulate the transitions between confinement and normal life, according to five different levels. The plasma treatment from recovered patients has also been considered in the control algorithm. Using the proposed strategy the ICU occupancy is reduced, and as a consequence, the number of deaths is also decreased.

}, issn = {0019-0578}, doi = {10.1016/j.isatra.2021.06.024}, author = {Garc{\'\i}a-Violini, Demi{\'a}n and S{\'a}nchez-Pe{\~n}a, Ricardo and Moscoso-V{\'a}squez, Marcela and Garelli, Fabricio} } @article {311, title = {Potentials of constrained sliding mode control as an intervention guide to manage COVID19 spread}, journal = {Biomedical Signal Processing and Control}, volume = {67}, year = {2021}, month = {03/2021}, pages = {102557}, abstract = {

This work evaluates the potential of using sliding mode reference conditioning (SMRC) techniques as a guide for non-pharmaceutical intervention (NPI) to control the COVID-19 pandemic. In particular, for the epidemiological problem addressed here, it is used to compute the contact rate reduction requirement in order to limit the infectious population to a given threshold. The SMRC controller allows the desired output variable limit and its approaching rate to be tuned explicitly. Implementation issues are taken into account and a periodically update of the NPI is proposed for the real life application. The strategy is evaluated under different scenarios where its distinctive features are exhibited.

}, issn = {1746-8094}, doi = {https://doi.org/10.1016/j.bspc.2021.102557}, author = {Nu{\~n}ez, Sebasti{\'a}n and Inthamoussou, Fernando A. and Valenciaga, Fernando and De Battista, Hern{\'a}n and Garelli, Fabricio} } @article {321, title = {Robust exact differentiators with predefined convergence time}, journal = {Automatica}, volume = {134}, year = {2021}, pages = {109858}, abstract = {

The problem of exactly differentiating a signal with bounded second derivative is considered. A class of differentiators is proposed, which converge to the derivative of such a signal within a fixed, i.e., a finite and uniformly bounded convergence time. A tuning procedure is derived that allows to assign an arbitrary, predefined upper bound for this convergence time. It is furthermore shown that this bound can be made arbitrarily tight by appropriate tuning. The usefulness of the procedure is demonstrated by applying it to the well-known uniform robust exact differentiator, which is included in the considered class of differentiators as a special case.

}, keywords = {Disturbance rejection, Finite-time convergence, Fixed-time convergence, Sliding modes, super-twisting algorithm}, issn = {0005-1098}, doi = {https://doi.org/10.1016/j.automatica.2021.109858}, url = {https://www.sciencedirect.com/science/article/pii/S0005109821003782}, author = {Seeber, Richard and Haimovich, Hernan and Horn, Martin and Fridman, Leonid M. and De Battista, Hern{\'a}n} } @article {292, title = {Adaptive PI control with robust variable structure anti-windup strategy for systems with rate-limited actuators: Application to compression systems}, journal = {Control Engineering Practice}, volume = {96}, year = {2020}, pages = {104282}, abstract = {

In this paper, an adaptive proportional{\textendash}integral (PI) control strategy for nonlinear systems with constrained actuators is discussed. In particular, a variable-structure anti-windup strategy that can be retrofitted onto different control structures is proposed and validated. Both the developed controller and anti-windup method are attuned to an automotive industrial control application: the control of air mass flow-rate and pressure in a fuel cell system using a high speed turbo-compressor and an electromechanical valve. Both the compressor and valve are rate-limited. The results from experimental tests agree with the simulations obtained and showing the effectiveness of the proposed approach by evidencing the fast control dynamics and the proper and desired closed-loop performance of the scheme without windup phenomena.

}, keywords = {Air compressor, Rate-limiter, Relay feedback test, Sliding mode anti-windup}, issn = {0967-0661}, doi = {https://doi.org/10.1016/j.conengprac.2019.104282}, url = {http://www.sciencedirect.com/science/article/pii/S0967066119302242}, author = {Eldigair, Yousif and Garelli, Fabricio and Kunusch, Cristian and Ocampo-Mart{\'\i}nez, Carlos} } @article {303, title = {Automatic glycemic regulation for the pediatric population based on switched control and time-varying IOB constraints: an in silico study}, journal = {Medical \& Biological Engineering \& Computing}, year = {2020}, month = {Jul}, abstract = {

Artificial pancreas (AP) systems have shown to improve glucose regulation in type 1 diabetes (T1D) patients. However, full closed-loop performance remains a challenge particularly in children and adolescents, since these age groups often present the worst glycemic control. In this work, an algorithm based on switched control and time-varying IOB constraints is presented. The proposed control strategy is evaluated in silico using the FDA-approved UVA/ Padova simulator and its performance contrasted with the previously introduced Automatic Regulation of Glucose (ARG) algorithm in the pediatric population. The effect of unannounced meals is also explored. Results indicate that the proposed strategy achieves lower hypo- and hyperglycemia than the ARG for both announced and unannounced meals.

}, issn = {1741-0444}, doi = {10.1007/s11517-020-02213-w}, url = {https://doi.org/10.1007/s11517-020-02213-w}, author = {Fushimi, Emilia and Serafini, Mar{\'\i}a Cecilia and De Battista, Hern{\'a}n and Garelli, Fabricio} } @article {304, title = {Combination of cascade and feed-forward constrained control for stable partial nitritation with biomass retention}, journal = {Journal of Process Control}, volume = {95}, year = {2020}, month = {09/2020}, pages = {55-66}, abstract = {

Ammonium removal is a key step in wastewater treatment which can be accomplished biologically. An
interesting process option for this purpose is coupling partial nitritation with the Anammox process.
The goal of the partial nitritation process is to convert half of the ammonium in the influent stream into
nitrite, so both can be later converted into dinitrogen gas by the Anammox reaction. To obtain a stable
partial nitritation, ammonium oxidizing bacteria (AOB) have to prevail over nitrite oxidizing bacteria
(NOB) so as to avoid further conversion of nitrite into nitrate. The dissolved oxygen concentration
is a key variable for the functional group selection. In this study, a constrained combination of
cascade and feedforward control is proposed for reactors with biomass retention, aimed at suppressing
unwanted NOB while keeping a nitrite:ammonium ratio suitable for coupling with Anammox. The
master controller, aimed to regulate this effluent ratio, generates the set-point for the dissolved oxygen
concentration slave controller. In addition to the cascade controller feedback loop, a feed-forward
controller calculates the optimal dissolved oxygen concentration based on the current influent stream
flow rate and concentrations. The resulting dissolved oxygen concentration set-point is compared to
constraints that guarantee the suppression of NOB and survival of AOB. The proposed control strategy is
simple to apply in common wastewater treatment plants with biomass retention. A sensitivity analysis
is performed to assess the effect of model parameters uncertainty on the controller constraints and
to determine which parameters need to be identified with more precision to avoid instability or poor
results. The performance and the effect of the uncertainty of the most sensitive parameters on the
proposed control algorithm are assessed through simulation using realistic streams as inputs of the
process.

}, doi = {10.1016/j.jprocont.2020.09.002}, url = {https://authors.elsevier.com/a/1bq0j3Q5WJJ30M}, author = {Jamilis, Mart{\'\i}n and Garelli, Fabricio and De Battista, Hern{\'a}n and Volcke, Eveline I.P.} } @article {299, title = {Control of a grid assisted PV-H2 production system: A comparative study between optimal control and hybrid MPC}, journal = {Journal of Process Control}, volume = {92}, year = {2020}, pages = {220 - 233}, abstract = {

Hydrogen production systems supplied by photovoltaic solar energy have nonlinear dynamics and discontinuities which must be taken into account when a control system is applied. The main purpose of the control system is to maintain the electrolyzer current at the desired operating point and, at the same time, to optimize the grid energy consumption despite the solar energy variability. Classic controllers, like PID ones, are not able to obtain good performance over the whole operation range of these kinds of plants because of the aforementioned characteristics. To overcome these limitations, an optimal control strategy and a linear hybrid model predictive controller (HMPC) are applied to a hydrogen production system in this work. Regarding the optimal control design, a systematic framework is presented in order to obtain the optimal (in the sense of minimal grid energy consumption) trajectory of the states by converting the control problem into a boundary value problem by means of the Pontryagin{\textquoteright}s Maximum Principle. Interestingly, the resulting control law is explicit and piecewise continuous. Regarding the linear HMPC strategy, a mixed logical dynamical description of the linearized equations of the system is considered in order to obtain the control law by solving an optimization problem in the form of a mixed integer quadratic programming. For this control strategy three cost functions associating the grid energy consumption and the electrolyzer efficiency are presented. The proposed controllers are tested through numerical simulations for both the nominal and uncertain cases and different performance indexes are considered. Finally, a discussion of the main advantages and disadvantages of each controller in real-life applications is presented.

}, issn = {0959-1524}, doi = {https://doi.org/10.1016/j.jprocont.2020.06.008}, author = {de Andrade, Gustavo A. and Mendes, Paulo R.C. and Garc{\'\i}a-Cl{\'u}a, Jos{\'e} G. and Normey-Rico, Julio E.} } @article {291, title = {Control-Oriented Model with Intra-Patient Variations for an Artificial Pancreas}, journal = {IEEE Journal of Biomedical and Health Informatics}, year = {2020}, pages = {1-1}, abstract = {

In this work, a low-order model designed for glucose regulation in T1DM is obtained from the UVA/Padova metabolic simulator. It captures not only the nonlinear behavior of the glucose-insulin system, but also intra-patient variations related to daily insulin sensitivity (${S_{I}}$) changes. To overcome the large inter-subject variability, the model can also be personalized based on a priori patient information. The structure is amenable for linear parameter varying (LPV) controller design, and represents the dynamics from the subcutaneous insulin input to the subcutaneous glucose output. The efficacy of this model is evaluated in comparison with a previous control-oriented model which in turn is an improvement of previous models. Both models are compared in terms of their open- and closed-loop differences with respect to the UVA/Padova model. The open-loop analysis is computed through the root mean square error (RMSE) between the glucose deviation predicted by the models and the UVA/Padova simulator. In closed-loop, the ν-gap metric is used to measure the distance in terms of closed-loop performance between the two models. The results are promising and some illustrative simulations are presented.

}, keywords = {Artificial pancreas, Control-oriented model, Intra-patient variations, LPV model, type 1 diabetes}, issn = {2168-2208}, doi = {10.1109/JBHI.2020.2969389}, author = {Moscoso-V{\'a}squez, Marcela and Colmegna, Patricio and Rosales, Nicol{\'a}s and Garelli, Fabricio and S{\'a}nchez-Pe{\~n}a, Ricardo} } @article {305, title = {A global optimization approach for sliding mode tuning and existence maps generation}, journal = {International Journal of Dynamics and Control}, year = {2020}, month = {10/2020}, abstract = {

In this work, global optimization techniques based on interval arithmetic are proposed to analyze and synthesize sliding mode (SM) controllers. The proposed methodology allows generating a series of maps, called subpavings, which put in evidence the required relationships among tuning parameters, disturbances and control amplitude to fulfill the sufficient condition of SM in a guaranteed way. The a priori knowledge of the control power necessary to guarantee SM behavior of nonlinear systems despite parameter uncertainties and external disturbances is an advantage of this proposal compared to traditional tuning methods, which usually fall into over-sizing solutions. Although the methodology is developed in the context of conventional first-order SM controllers, it could be extended to any other SM design approach.

}, issn = {2195-2698}, doi = {10.1007/s40435-020-00702-2}, author = {Rosendo, Juan L. and Monnet, Dominique and De Battista, Hern{\'a}n and Ninin, Jordan and Clement, Benoit and Garelli, Fabricio} } @mastersthesis {295, title = {Modelado y simulaci{\'o}n de tecnolog{\'\i}as para el tratamiento de la diabetes}, year = {2020}, month = {04/2020}, school = {Universidad Nacional de La Plata}, type = {PhD}, abstract = {

En las {\'u}ltimas dos d{\'e}cadas hubo un gran crecimiento en la investigaci{\'o}n y el desarrollo de sistemas de P{\'a}ncreas Artificial (PA). Estos sistemas, compuestos por un lazo de control realimentado, una bomba de insulina y un sensor continuo de glucosa, permiten la regulaci{\'o}n autom{\'a}tica de glucosa para personas con Diabetes Mellitus Tipo I (DMT1). A{\'u}n as{\'\i}, las limitaciones que presenta este desaf{\'\i}o, como los son la gran variabilidad inter- e intrapaciente, la incertidumbre y retardos del sistema, dificultan la concepci{\'o}n de un control de lazo cerrado puro. Adem{\'a}s de estas limitaciones, el riesgo de exponer a la persona a hiper- e hipoglucemias es un gran impedimento a la hora de desarrollar las estrategias de control gluc{\'e}mico. En esta tesis se plantean objetivos que cubren distintos aspectos del desarrollo de terapias para el control de la glucosa en la DMT1. En primer lugar, se desarroll{\'o} una plataforma de simulaci{\'o}n que cuenta con un amplio espectro de configuraciones. Luego, a partir de la estimaci{\'o}n de la insulina activa en el cuerpo (IOB), se proponen dos algoritmos para el tratamiento a lazo abierto: uno para peri{\'o}dos posprandiales y otro para la actividad f{\'\i}sica. A su vez, a partir de la limitaci{\'o}n de IOB, se proponen t{\'e}cnicas de lazo cerrado. Por un lado, se propone un algoritmo que permite la transici{\'o}n en confi guraciones h{\'\i}bridas, entre el bolo posprandial de lazo abierto y el controlador de lazo cerrado. Por otro lado, a partir de una participaci{\'o}n interdisciplinaria, se presenta el desarrollo y ensayo cl{\'\i}nico de un algoritmo de control de lazo cerrado sin bolo para la compensaci{\'o}n de comidas. Por {\'u}ltimo, se presenta el algoritmo GSAFE para lazos cerrados de control puro donde se propone adaptar la salida de un controlador principal con el fin de imponer una limitaci{\'o}n en la pendiente de ca{\'\i}da de glucosa con el objetivo de prevenir futuras hipoglucemias debido a la sobreactuaci{\'o}n.

}, url = {http://sedici.unlp.edu.ar/handle/10915/97299}, author = {Rosales, Nicol{\'a}s} } @article {306, title = {Predictive management approach for the coordination of wind and water-based power supplies}, journal = {Energy}, year = {2020}, pages = {119535}, abstract = {

This paper addresses the coordinated operation between wind farms and reservoir hydropower plants in networks with weak transmission capacity. The joint operation of the energy sources is captured by a Virtual Power Plant (VPP) representation. With the aim of maximising renewable energy penetration while ensuring a suitable VPP integration, a supervisory controller for the energy dispatch layer is proposed. To deal with the variable nature of both resources, the controller has been designed into a model predictive control framework including mixed-integer quadratic programming (given the hybrid considered model) for solving the related optimisation problem, and complementary techniques as constraints softening and time-varying weighting. The results indicate that the predictive control approach achieves a better Independent System Operator (ISO) reference tracking that, together with reservoir management, are the most important factors to ensure a suitable VPP incorporation to the main grid. As a case study, a sub-network of the Argentinian power system is tackled. The controller performance is quantitatively and qualitatively assessed under uncertain conditions and compared with other approaches over a nine-year period. By means of the proposed power management policy, the ISO{\textquoteright}s effort to balance the sub-network is reduced 56\% with regard to other approaches without any water spillage.

}, issn = {0360-5442}, doi = {https://doi.org/10.1016/j.energy.2020.119535}, author = {Levieux, Luis I. and Ocampo-Mart{\'\i}nez, Carlos and Inthamoussou, Fernando A. and De Battista, Hern{\'a}n} } @article {307, title = {Remote Glucose Monitoring Platform for Multiple Simultaneous Patients at Coronavirus Disease 2019 Intensive Care Units: Case Report Including Adults and Children}, journal = {Diabetes Technology \& Therapeutics}, year = {2020}, month = {12/2020}, doi = {10.1089/dia.2020.0556}, url = {https://doi.org/10.1089/dia.2020.0556}, author = {Garelli, Fabricio and Rosales, Nicol{\'a}s and Fushimi, Emilia and Arambarri, Delfina and Mendoza, Leandro and De Battista, Hern{\'a}n and S{\'a}nchez-Pe{\~n}a, Ricardo and Garc{\'\i}a Arabehety, Julia and Distefano, Sabrina and Barcala, Consuelo and Giunta, Javier and Las Heras, Marcos and Martinez Mateu, Carolina and Prieto, Mariana and San Rom{\'a}n, Eduardo and Krochik, Gabriela and Grosembacher, Luis} } @article {286, title = {Wind turbine load analysis of a full range LPV controller}, journal = {Renewable Energy}, year = {2020}, abstract = {

A wind turbine load analysis featuring both fatigue and extreme loads for a full range Linear Parameter Varying (LPV) controller is presented in this paper. The National Renewable Energy Laboratory (NREL) 5 MW reference wind turbine is simulated with realistic profiles of turbulent wind, according to the IEC 61400-1 regulation, using several NREL{\textquoteright}s tools, with a total of 354 numerical simulations. Classical techniques has been applied, like the Rain-flow counting (RFC) algorithm, and the Palmgren-Miner Rule with Goodman{\textquoteright}s correction to estimate the wind turbine components damage rate. The mechanical loads under consideration are the tower and blades main moments. The results show a lifetime equivalent load reduction with the LPV controller in comparison with the classical Gain Scheduling Proportional Integral (GSPI), for all analyzed loads, similar to those achieved by other publications in the literature. This improvement is achieved using the same online measurements and information as the used by the GSPI controller.

}, keywords = {Fatigue analysis, Mechanical loads, Wind turbine}, issn = {0960-1481}, doi = {https://doi.org/10.1016/j.renene.2019.08.016}, url = {http://www.sciencedirect.com/science/article/pii/S0960148119312030}, author = {Ib{\'a}{\~n}ez, Bernab{\'e} and Inthamoussou, Fernando A. and De Battista, Hern{\'a}n} } @article {284, title = {Analysis of Transcriptional Feedback Strategy for Reducing Interaction in Gene Expression Processes}, journal = {IFAC-PapersOnLine}, volume = {52}, year = {2019}, pages = {526 - 531}, abstract = {

Advances in genetic manipulation have allowed the overexpression of proteins and insertion of circuits in cells. However, the expected behaviour can be altered by the internal competition for the limited amount of cellular resources. In this work we analyse a feedback strategy based on transcription inhibition that aims to reduce the interaction in a two-protein expression system. The results allow interpreting the effects of negative feedback on the steady-state protein levels and how the realizable protein region is affected by the feedback loop.

}, issn = {2405-8963}, doi = {10.1016/j.ifacol.2019.06.116}, author = {Nu{\~n}ez, Sebasti{\'a}n and Garelli, Fabricio and Pic{\'o}, Jes{\'u}s and De Battista, Hern{\'a}n} } @inbook {244, title = {The ARG algorithm: clinical trials in Argentina}, booktitle = {The Artificial Pancreas: current situation and future directions}, year = {2019}, pages = {79-104}, publisher = {Academic Press}, organization = {Academic Press}, chapter = {4}, abstract = {

The objective of this work is to present a brief review of the control design problem for glucose regulation in T1DM. In particular, control-oriented models, and robust and time-varying controllers will be mentioned. Characteristics of diabetes in general and T1DM in particular in the context of Latin America will be described. Finally, the Automatic Regulation of Glucose (ARG) algorithm will be presented, including in silico and clinical results.

}, issn = {9780128156551}, doi = {https://doi.org/10.1016/B978-0-12-815655-1.00013-2}, author = {Colmegna, Patricio and Garelli, Fabricio and De Battista, Hern{\'a}n and Bianchi, Fernando D. and S{\'a}nchez-Pe{\~n}a, Ricardo} } @article {285, title = {Artificial Pancreas: Evaluating the ARG Algorithm Without Meal Announcement}, journal = {Journal of Diabetes Science and Technology}, year = {2019}, pages = {1932296819864585}, abstract = {

Background:Either under standard basal-bolus treatment or hybrid closed-loop control, subjects with type 1 diabetes are required to count carbohydrates (CHOs). However, CHO counting is not only burdensome but also prone to errors. Recently, an artificial pancreas algorithm that does not require premeal insulin boluses{\textemdash}the so-called automatic regulation of glucose (ARG){\textemdash}was introduced. In its first pilot clinical study, although the exact CHO counting was not required, subjects still needed to announce the meal time and classify the meal size.Method:An automatic switching signal generator (SSG) is proposed in this work to remove the manual mealtime announcement from the control strategy. The SSG is based on a Kalman filter and works with continuous glucose monitoring readings only.Results:The ARG algorithm with unannounced meals (ARGum) was tested in silico under the effect of different types of mixed meals and intrapatient variability, and contrasted with the ARG algorithm with announced meals (ARGam). Simulations reveal that, for slow-absorbing meals, the time in the euglycemic range, [70-180] mg/dL, increases using the unannounced strategy (ARGam: 78.1 [68.6-80.2]\% (median [IQR]) and ARGum: 87.8 [84.5-90.6]\%), while similar results were found with fast-absorbing meals (ARGam: 87.4 [86.0-88.9]\% and ARGum: 87.6 [86.1-88.8]\%). On the other hand, when intrapatient variability is considered, time in euglycemia is also comparable (ARGam: 81.4 [75.4-83.5]\% and ARGum: 80.9 [77.0-85.1]\%).Conclusion:In silico results indicate that it is feasible to perform an in vivo evaluation of the ARG algorithm with unannounced meals.

}, doi = {10.1177/1932296819864585}, url = {https://doi.org/10.1177/1932296819864585}, author = {Fushimi, Emilia and Colmegna, Patricio and De Battista, Hern{\'a}n and Garelli, Fabricio and S{\'a}nchez-Pe{\~n}a, Ricardo} } @article {254, title = {Disturbance-tailored super-twisting algorithms: Properties and design framework}, journal = {Automatica}, volume = {101}, year = {2019}, pages = {318 - 329}, abstract = {

Second- and higher-order sliding mode techniques are able to avoid the chattering effect associated with first-order sliding. The super-twisting algorithm is one of the most popular second-order sliding mode techniques. Existing modifications of the super-twisting algorithm allow for improved disturbance rejection capability. In this paper, we introduce a new class of generalizations of the super-twisting algorithm that are able to keep the main advantages of standard super-twisting while rejecting disturbances bounded in forms for which the existing algorithms may be not directly applicable. Our results thus broaden the applicability of second-order sliding-mode techniques. We give conditions for stability and finite-time convergence, and provide a complete design framework based on given disturbance bounds.

}, issn = {0005-1098}, doi = {https://doi.org/10.1016/j.automatica.2018.12.017}, author = {Haimovich, Hernan and De Battista, Hern{\'a}n} } @article {302, title = {Extraction of the minority carrier transport properties of solar cells using the Hovel model and genetic algorithms}, journal = {Measurement Science and Technology}, volume = {31}, year = {2019}, month = {nov}, pages = {025601}, abstract = {

In this paper, a quick and accurate method for extraction of the minority carrier transport properties of p-n or n-p junction solar cells, such as diffusion lengths and surface recombination velocities, is presented. The knowledge of these parameters is essential to investigating factors that limit the performance of photovoltaic devices. The proposed method, based on genetic algorithms and the analytical Hovel model, is used to fit the external quantum efficiency (EQE) curves of solar cells with different emitter thicknesses. As a demonstrative example of application of the procedure carried out in this work, theoretical and experimental EQE curves of n-p GaAs solar cells under the standard AM1.5G spectrum have been used in order to extract the desired parameters. Errors less than 2.4\% have been obtained, which shows the capability of the developed tool. An analysis of the total number of iterations is presented. The results obtained can be used to improve the design, optimization, and manufacturing process of high-efficiency photovoltaic devices.

}, doi = {10.1088/1361-6501/ab46e4}, author = {Cappelletti, Marcelo and C{\'e}dola, A. and Olivera, Lucas M and Casas, Guillermo and Osio, Jorge R. and Peltzer y Blanc{\'a}, E.} } @article {283, title = {In silico optimization of lipid production in Rhodosporidium toruloides by gene knockout strategies}, journal = {IFAC-PapersOnLine}, volume = {52}, year = {2019}, pages = {94 - 99}, abstract = {

Microbial lipids are being extensively studied as an alternative to vegetable oils in biodiesel production. For the biotechnological production of biolipids, efficient processes capable of obtaining significant biomass productivity with high lipid titer are required. In this work, we used the Optknock algorithm for the assessment of non-intuitive knockouts using a metabolic model for lipid production in R. toruloides. Four computationally designed mutants were obtained by the deletion of the genes involved in PGI1, GDH1, IDH and IDP1 reactions. In these strains, lipid metabolism is fully coupled to growth, with maximum productivities ranging from 26 to 62\% of lipids. By analyzing the maximum yield together with the flux distribution obtained from different knockouts, it was concluded that the double knockout strategy was an interesting alternative for obtaining growth-linked lipid production with few genetic manipulations.

}, keywords = {Gene knockout strategies, Metabolic engineering, Microbial lipids, Optknock}, issn = {2405-8963}, doi = {https://doi.org/10.1016/j.ifacol.2019.06.043}, url = {http://www.sciencedirect.com/science/article/pii/S2405896319301284}, author = {Casta{\~n}eda, Mar{\'\i}a Teresita and Nu{\~n}ez, Sebasti{\'a}n and Voget, Claudio and De Battista, Hern{\'a}n} } @article {312, title = {Interval Simulator of the Glucose-Insulin System}, journal = {Applied Computer Sciences in Engineering}, year = {2019}, abstract = {

In this paper, an interval simulator that considers different sources of uncertainty to estimate the blood glucose level of type 1 diabetes patients is presented. In particular, this study examines a model that includes the dynamics from the insulin delivery input to the subcutaneous-glucose concentration output, and a model that estimates the insulin-on-board considering uncertainty. Each model is studied using modal interval analysis to achieve an optimal computation. The simulator includes several interval models that can be combined with each other in order to expand possibilities in the design and assessment of the glucose regulation algorithms and insulin therapies for diabetes patients. The main features of the interval simulator are shown in this work.

}, isbn = {978-3-030-31019-6}, doi = {10.1007/978-3-030-31019-6_58}, author = {Garc{\'\i}a-Jaramillo, Maira and Le{\'o}n-Vargas, Fabi{\'a}n and Rosales, Nicol{\'a}s and Molano, Andr{\'e}s and Garelli, Fabricio}, editor = {Figueroa-Garc{\'\i}a, Juan Carlos and Duarte-Gonz{\'a}lez, Mario and Jaramillo-Isaza, Sebasti{\'a}n and Orjuela-Ca{\~n}on, Alvaro David and D{\'\i}az-Gutierrez, Yesid} } @article {287, title = {L-Fenilalanina amonio liasa (PAL) de Rhodosporidium toruloides NBRC 0559. Producci{\'o}n, caracterizaci{\'o}n e inmovilizaci{\'o}n por encapsulaci{\'o}n en membranas celul{\'o}sicas.}, journal = {Ingenio Tecnol{\'o}gico}, volume = {1}, year = {2019}, abstract = {

Con el objetivo de dise{\~n}ar un biocatalizador para la reducci{\'o}n del contenido en L-Fenilalanina con aplicaci{\'o}n a la producci{\'o}n de f{\'o}rmulas para pacientes con Fenilcetonuria, PAL fue obtenida a partir de Rhodosporidium toruloides NBRC 0559. Luego, PAL fue recuperada, purificada, inmovilizada por encapsulaci{\'o}n en membranas semipermeables y empleada en: a) reactor de columna con recirculaci{\'o}n y b) reactor tipo tanque agitado. La bioconversi{\'o}n se monitore{\'o} espectrofotom{\'e}tricamente (DO290) siguiendo la producci{\'o}n de {\'a}cido t-cin{\'a}mico. La enzima obtenida evidenci{\'o} una elevada actividad enzim{\'a}tica, gran afinidad por el sustrato y una temperatura {\'o}ptima de ~ 43{\textdegree}C. En cuanto al empleo de PAL inmovilizada, la utilizaci{\'o}n de un reactor tipo tanque agitado result{\'o} {\'o}ptima para la reducci{\'o}n de L-fenilalanina dado el efecto de la agitaci{\'o}n en la reducci{\'o}n del espesor de la pel{\'\i}cula estanca adyacente a la membrana. El factor m{\'a}s influyente en la velocidad de reacci{\'o}n fue el espesor de membrana, alcanzando de este modo la eliminaci{\'o}n completa de una soluci{\'o}n 0,1 mM de L-Fenilalanina en 6 h. En conclusi{\'o}n, PAL inmovilizada por encapsulaci{\'o}n en membranas celul{\'o}sicas es un m{\'e}todo viable para la reducci{\'o}n del contenido de L-Fenilalanina en soluciones diluidas. Este m{\'e}todo podr{\'\i}a extrapolarse a sustratos m{\'a}s complejos como lo son hidrolizados proteicos.

}, url = {http://ingenio.frlp.utn.edu.ar/index.php/ingenio/article/view/9}, author = {Casta{\~n}eda, Mar{\'\i}a T. and Adachi, Osao and Hours, Roque A.} } @article {282, title = {Operating conditions analysis for a partial nitritation process with biomass retention.}, journal = {IFAC-PapersOnLine}, volume = {52}, year = {2019}, month = {07/2019}, pages = {643 - 648}, abstract = {

In wastewater treatment, ammonium removal is a key step which can be done biologically. One method is by coupling a partial nitritation with the Anammox process. The partial nitritation goal is to convert half of the ammonium into nitrite, so ammonium and nitrite can be later converted into dinitrogen gas by Anammox bacteria. To obtain a stable partial nitritation, ammonium oxidizing bacteria (AOB) have to prevail over nitrite oxidizing bacteria (NOB) so as to avoid further conversion of nitrite into nitrate. Two control objectives can be identified for partial nitritation: the repression of NOB and the regulation of the effluent to obtain the required nitrite to ammonium ratio. In this work, the equilibrium points of the partial nitrification process are analyzed to find operating conditions for AOB prevalence over NOB. Based on this analysis, a feeding strategy is proposed to regulate the effluent nitrite to ammonium ratio at the value required by Anammox. The study is based on the process dynamical model in a reactor with biomass retention.

}, keywords = {Control, Energy Biosystems, Environmental, Model-based Optimization}, issn = {2405-8963}, doi = {https://doi.org/10.1016/j.ifacol.2019.06.135}, url = {http://www.sciencedirect.com/science/article/pii/S2405896319302228}, author = {Mart{\'\i}n Jamilis and Fabricio Garelli and Hern{\'a}n De Battista and Eveline I.P. Volcke} } @article {243, title = {Output Feedback Linearization of Turbidostats After Time Scaling}, journal = {IEEE Transactions on Control Systems Technology}, volume = {27}, year = {2019}, pages = {1668-1676}, abstract = {

Turbidostats are a class of bioreactors gaining interest due to the recent availability of microscale and small-scale devices for characterization and scalingup of the biotechnological systems relevant in the biotech and pharma industries. The goal is to keep cell density constant in continuous operation. Thus, the control law, i.e., the substrate feeding strategy, must guarantee global or semiglobal convergence to an equilibrium point. However, their control is difficult due to the uncertain, time varying, and nonlinear nature of the processes involved. In this brief, we propose an adaptive control law that globally stabilizes the desired biomass setpoint. Furthermore, in a certain region of the state space, the controller linearizes the dynamic behavior after some time scaling. By this way, the orbits of the closed-loop system are imposed by the designer. The intrinsic integral action of the gain adaptation rejects the parameter uncertainties. Moreover, the controller implementation only assumes the biomass concentration to be measured. Both the simulated and experimental results show the performance of the controller.

}, keywords = {adaptive control, Asymptotic stability, Biological system modeling, Biomass, Bioreactors, Convergence, Nonlinear control systems, output feedback, Substrates}, issn = {1063-6536}, doi = {10.1109/TCST.2018.2834882}, author = {De Battista, Hern{\'a}n and Pic{\'o}-Marco, Enric and Santos-Navarro, Fernando N. and Pic{\'o}, Jes{\'u}s.} } @article {249, title = {Power dispatch assessment of a wind farm and a hydropower plant: A case study in Argentina}, journal = {Energy Conversion and Management}, volume = {180}, year = {2019}, pages = {391 - 400}, abstract = {

This work aims to analyze the complementary operation between an existing hydropower plant and a projected wind farm in a remote area of Argentinean Patagonia. With this new generation, the grid element sizes will be insufficient to handle both generation sources at rated. Particulary, a bottleneck will be present at the transmission line and the coupling transformer with the main grid. To avoid this situation, a coordinated dispatch policy of both generation sources is proposed. With this aim, a heuristic algorithm is developed that improves energy generation under the transmission system restrictions. The proposal is assessed and compared with other operation policies on the basis of real data collected over nine years. The benefits of the proposal, that basically consists in reducing wind and hydro power spillage are highlighted. Furthermore, the impact of enlarging the wind farm on the overall power system production is also evaluated.

}, issn = {0196-8904}, doi = {https://doi.org/10.1016/j.enconman.2018.10.101}, url = {http://www.sciencedirect.com/science/article/pii/S0196890418312299}, author = {Levieux, Luis I. and Inthamoussou, Fernando A. and De Battista, Hern{\'a}n} } @mastersthesis {288, title = {Robust techniques of automatic control for mobile robotic systems}, volume = {PhD}, year = {2019}, month = {02/2019}, school = {Universidad Nacional de La Plata}, type = {PhD thesis}, address = {La Plata, Buenos Aires, Argentina}, abstract = {

This work seeks to mitigate the effects of constraints on mobile robotic systems. To this end, auxiliary control loops and robust tuning techniques are proposed. The former are proposed to mitigate the effects of constraints on the input and output of the systems through the modification of the motion parameter in path following applications. Then, PID controllers are considered as a structural constraint, given its wide use in robotics particularly at low control level. A robust tuning methodology considering this constraint is proposed which achieves good performance levels even when facing disturbances. Finally, to deal with robustness in presence of robots nonlinearity constraints, an analysis and tuning tool for sliding mode controllers is proposed. The particularity of this tuning method, based on global optimization and interval techniques, is that it allows generating tuning maps of the parameter regions where the desired performance criterion is fulfilled. All the proposed strategies are put into practice, through real experimentation or in validated simulators, over the AUV Ciscrea available at ENSTA Bretagne.

}, url = {http://sedici.unlp.edu.ar/handle/10915/75671}, author = {Rosendo, Juan L.} } @article {255, title = {Stability and control of a partial nitritation reactor with biomass retention}, journal = {Chemical Engineering Research and Design}, volume = {144}, year = {2019}, month = {04/2019}, pages = {318-333}, abstract = {

Partial nitritation-anammox process is an interesting process option for biological nitrogen removal from wastewater. Partial nitritation needs to provide about equimolar ammonium and nitrite concentrations as required for the Anammox conversion. This study analyzes the equilibrium points of a stand-alone partial nitritation process as part of a two-reactor partial nitritation-anammox configuration. Conditions for the feasibility and stability of the equilibrium points are obtained in the general case of a reactor with biomass retention and controlled oxygen concentration. This knowledge is subsequently applied to achieve the desired reactor behavior, namely suppressing nitrite oxidizing bacteria (NOB) and obtaining the desired effluent nitrite:ammonium ratio. The optimal oxygen concentration to achieve these two objectives is determined. Moreover, a control algorithm is proposed to drive the process to the desired operating point. Its steady state behavior is assessed for changing influent ammonium concentrations and biomass retention times. The dynamic performance of the controller is tested through simulation as well, prioritizing NOB suppression in case the two objectives are not compatible.

}, keywords = {Anammox, Bacteria Competition, Control, Equilibrium Points, Partial nitritation}, issn = {0263-8762}, doi = {https://doi.org/10.1016/j.cherd.2019.02.017}, url = {http://www.sciencedirect.com/science/article/pii/S0263876219300644}, author = {Mart{\'\i}n Jamilis and Fabricio Garelli and Hern{\'a}n De Battista and Eveline I.P. Volcke} } @article {245, title = {Artificial Pancreas: Clinical Study in Latin America Without Premeal Insulin Boluses}, journal = {Journal of Diabetes Science and Technology}, volume = {12}, year = {2018}, month = {07/2018}, pages = {914 - 925}, abstract = {

Background: Emerging therapies such as closed-loop (CL) glucose control, also known as artificial pancreas (AP) systems, have shown significant improvement in type 1 diabetes mellitus (T1DM) management. However, demanding patient intervention is still required, particularly at meal times. To reduce treatment burden, the automatic regulation of glucose (ARG) algorithm mitigates postprandial glucose excursions without feedforward insulin boluses. This work assesses feasibility of this new strategy in a clinical trial.

Methods: A 36-hour pilot study was performed on five T1DM subjects to validate the ARG algorithm. Subjects wore a subcutaneous continuous glucose monitor (CGM) and an insulin pump. Insulin delivery was solely commanded by the ARG algorithm, without premeal insulin boluses. This was the first clinical trial in Latin America to validate an AP controller.

Results: For the total 36-hour period, results were as follows: average time of CGM readings in range 70-250 mg/dl: 88.6\%, in range 70-180 mg/dl: 74.7\%, \<70 mg/dl: 5.8\%, and \<50 mg/dl: 0.8\%. Results improved analyzing the final 15-hour period of this trial. In that case, the time spent in range was 70-250 mg/dl: 94.7\%, in range 70-180 mg/dl: 82.6\%, \<70 mg/dl: 4.1\%, and \<50 mg/dl: 0.2\%. During the last night the time spent in range was 70-250 mg/dl: 95\%, in range 70-180 mg/dl: 87.7\%, \<70 mg/dl: 5.0\%, and \<50 mg/dl: 0.0\%. No severe hypoglycemia occurred. No serious adverse events were reported.

Conclusions: The ARG algorithm was successfully validated in a pilot clinical trial, encouraging further tests with a larger number of patients and in outpatient settings.

}, doi = {10.1177/1932296818786488}, author = {S{\'a}nchez-Pe{\~n}a, Ricardo and Colmegna, Patricio and Garelli, Fabricio and De Battista, Hern{\'a}n and Garc{\'\i}a-Violini, Demi{\'a}n and Moscoso-V{\'a}squez, Marcela and Rosales, Nicol{\'a}s and Fushimi, Emilia and Campos-N{\'a}{\~n}ez, Enrique and Breton, Marc and Beruto, Valeria and Scibona, Paula and Rodriguez, Cintia and Giunta, Javier and Simonovich, Ventura and Belloso, Waldo H. and Cher{\~n}avvsky, Daniel and Grosembacher, Luis} } @article {242, title = {Artificial pancreas clinical trials: Moving towards closed-loop control using insulin-on-board constraints}, journal = {Biomedical Signal Processing and Control}, volume = {45}, year = {2018}, pages = {1 - 9}, abstract = {

Abstract Artificial pancreas (AP) systems for people with type 1 diabetes (T1DM) combine the use of a smart insulin pump with a Continuous Glucose Monitor (CGM) and a control algorithm to improve the regulation of glycaemia. Based on the extensive clinical evidence provided by the main research groups in the area, a hybrid control algorithm combining insulin meal boluses and glucose feedback action has been recently approved. However, this sort of algorithms should be refined especially during the postprandial period. In turn, fully closed-loop control strategies have to be further developed. In either case, intensive in vivo validation is necessary to ensure the viability of the proposed strategy as an effective method to treat \{T1DM\} patients. In this paper, a safety layer called \{SAFE\} loop [1] is reformulated to be employed during clinical trials in two different ways: the time enable mode to gradually activate the closed-loop control after an insulin meal bolus in hybrid configurations; and the amplitude enable mode to activate the full closed-loop control as long as the insulin infusion does not exceed the conventional therapy to a given extent. The \{SAFE\} module decides the activation of the controller as a function of a constraint on the insulin on board (IOB). In the case of the Time Enable, this results in the use of a constant restriction on the IOB, whereas in the amplitude enable it results in the use of a time-varying {\.I}OB\} constraint. Both operation modes are evaluated in silico using broadly accepted high-order models and the results contrasted with the ones obtained without the \{SAFE\} protection.

}, keywords = {insulin-on-board}, issn = {1746-8094}, doi = {https://doi.org/10.1016/j.bspc.2018.05.009}, url = {https://www.sciencedirect.com/science/article/pii/S1746809418301113}, author = {Fushimi, Emilia and Rosales, Nicol{\'a}s and De Battista, Hern{\'a}n and Garelli, Fabricio} } @article {235, title = {Automatic regulatory control in type 1 diabetes without carbohydrate counting}, journal = {Control Engineering Practice}, volume = {74}, year = {2018}, pages = {22 - 32}, abstract = {

A new approach to automatically regulate the glucose level in type 1 diabetes is presented in this work. This is the so-called Automatic Regulation of Glucose (ARG) algorithm, which is based on a switched Linear Quadratic Gaussian (LQG) inner controller, combined with an outer sliding mode safety loop with Insulin on Board (IOB) constraints. In silico and in vivo results without feedforward insulin boluses delivered at meal times indicate that safe blood glucose control can be achieved by the proposed controller. This controller is simple to migrate to well-known hardware platforms, and intuitive to tune using a priori clinical information.

}, issn = {0967-0661}, doi = {https://doi.org/10.1016/j.conengprac.2018.02.003}, author = {Colmegna, Patricio and Garelli, Fabricio and De Battista, Hern{\'a}n and S{\'a}nchez-Pe{\~n}a, Ricardo} } @article {241, title = {Comprehensive analysis of a Metabolic Model for lipid production in Rhodosporidium toruloides}, journal = {Journal of Biotechnology}, volume = {280}, year = {2018}, pages = {11 - 18}, abstract = {

The yeast Rhodosporidium toruloides has been extensively studied for its application in biolipid production. The knowledge of its metabolism capabilities and the application of constraint-based flux analysis methodology provide useful information for process prediction and optimization. The accuracy of the resulting predictions is highly dependent on metabolic models. A metabolic reconstruction for R. toruloides metabolism has been recently published. On the basis of this model, we developed a curated version that unblocks the central nitrogen metabolism and, in addition, completes charge and mass balances in some reactions neglected in the former model. Then, a comprehensive analysis of network capability was performed with the curated model and compared with the published metabolic reconstruction. The flux distribution obtained by lipid optimization with Flux Balance Analysis was able to replicate the internal biochemical changes that lead to lipogenesis in oleaginous microorganisms. These results motivate the development of a genome-scale model for complete elucidation of R. toruloides metabolism.

}, issn = {0168-1656}, doi = {https://doi.org/10.1016/j.jbiotec.2018.05.010}, author = {Casta{\~n}eda, Mar{\'\i}a T. and Nu{\~n}ez, Sebasti{\'a}n and Garelli, Fabricio and Voget, Claudio and De Battista, Hern{\'a}n} } @article {309, title = {Control of an Autonomous Underwater Vehicle subject to robustness constraints}, journal = {IFAC-PapersOnLine}, volume = {51}, year = {2018}, pages = {322-327}, abstract = {

In this paper, we present a method to compute a control law for an Autonomous Underwater Vehicle (AUV) subject to external disturbances. The control law{\textquoteright}s design objectives are formulated as H$\infty$ objectives used to synthesize a robust controller. Then, a robustness analysis of AUV model uncertainties is performed without conservatism with interval analysis and global optimization in order to validate the control law. We emphasize the advantage of our approach by comparing it with two other classical design methods with simulations and experiments.

}, issn = {2405-8963}, doi = {https://doi.org/10.1016/j.ifacol.2018.11.127}, author = {Rosendo, Juan L. and Monnet, Dominique and Clement, Benoit and Garelli, Fabricio and Ninin, Jordan} } @article {246, title = {Experimental validation of constraint mitigation algorithm in underwater robot depth control}, journal = {Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering}, year = {2018}, month = {08/2018}, abstract = {

This work explores both modeling and control of the experimental Ciscrea autonomous underwater vehicle. A 6-degree-of-freedom model is presented and validated for turn and emerge/sink maneuvers. Then, a constraint compensating algorithm is proposed based on quasi-sliding mode conditioning ideas and added to a pre-existing inaccessible proportional-derivative controller in order to improve the overall closed-loop response. By considering actuator constraints, the employed technique allows path following at greater speed than the original controller for a given error tolerance. Experimental results on the so-called Ciscrea underwater robot are presented.

}, doi = {10.1177/0959651818791399}, author = {Rosendo, Juan L. and Clement, Benoit and Garelli, Fabricio} } @article {310, title = {A global optimization approach for non-linear sliding mode control analysis and design}, journal = {IFAC-PapersOnLine}, volume = {51}, year = {2018}, pages = {128-133}, abstract = {

The design of sliding mode (SM) comprises the selection of a sliding manifold on the state space and a switching logic. The sliding manifold design is associated with the desired dynamics and closed loop specifications, whereas the switching logic is designed to drive and keep the state on the prescribe manifold. The classical design can lead to over or underestimation of the sliding domain, the closed loop robustness and the necessary control power. Here the design of SM is addressed from the global optimization approach using interval arithmetic. A solution to the analysis and synthesis problems of SM design is provided, where the necessary and sufficient conditions are fulfilled in a guaranteed way. For the analysis problem the proposed methodology allows checking sliding mode behaviour over given state domain and parameter sets. For the synthesis problem, the methodology allows designing the sliding manifold and switching logic with a given optimization criterion. The methodology is illustrated with a concluding example.

}, issn = {2405-8963}, doi = {https://doi.org/10.1016/j.ifacol.2018.11.093}, author = {Monnet, Dominique and Rosendo, Juan L. and De Battista, Hern{\'a}n and Clement, Benoit and Ninin, Jordan and Garelli, Fabricio} } @article {232, title = {Global stabilisation of continuous bioreactors: Tools for analysis and design of feeding laws}, journal = {Automatica}, volume = {89}, year = {2018}, pages = {340 - 348}, abstract = {

This work revisits the dynamic behaviour of stirred continuous reactors in which a single bioreaction with unknown kinetics occurs. Conditions on the feeding strategy to avoid washing out the biomass and falling in batch operation are obtained. These conditions derive in a closed positively invariant region including the desired operating point. It is stated that no closed orbits may exist in this region and, furthermore, that no fixed point exists but on one of its borders. Therefore, global stability is achieved by finding a feeding law that fulfils the aforementioned invariant conditions and gives a single equilibrium for a first-order dynamics. These results are useful to determine the stability properties of different control laws and, more importantly, to design new ones. The main advantages of the proposed approach are its simplicity and that, differing from previous results, input saturation does not affect stability results. The potentiality of the developed tools is illustrated by means of classical and novel feeding laws.

}, keywords = {Bioprocess control, Invariant control, Nonlinear control}, issn = {0005-1098}, doi = {https://doi.org/10.1016/j.automatica.2017.12.041}, author = {De Battista, Hern{\'a}n and Jamilis, Mart{\'\i}n and Garelli, Fabricio and Pic{\'o}, Jes{\'u}s} } @article {237, title = {Growth rate maximization in fed-batch processes using high order sliding controllers and observers based on cell density measurement}, journal = {Journal of Process Control}, volume = {68}, year = {2018}, month = {04/2018}, pages = {23 - 33}, abstract = {

A novel extremum seeking scheme is proposed for the optimization of the specific growth rate in fed-batch processes with substrate inhibited kinetics. The proposed controller is based on a high order sliding mode algorithm, which uses the gradient of the specific growth rate as switching coordinate. A gradient estimation is obtained through a high order sliding mode observer. Both the control and gradient estimation algorithms are finite-time stable. The stability of the controller is analysed using Lyapunov functions for both the unperturbed and perturbed cases and guidelines for the algorithm tuning are provided. The controller and observer algorithms are numerically assessed and simulation results are obtained for a set of different scenarios.

}, keywords = {extremum seeking, Fed-batch, Gradient, Sliding mode}, issn = {0959-1524}, doi = {https://doi.org/10.1016/j.jprocont.2018.04.003}, url = {https://www.sciencedirect.com/science/article/pii/S0959152418300659}, author = {Jamilis, Mart{\'\i}n and Garelli, Fabricio and De Battista, Hern{\'a}n} } @article {234, title = {Limiting vertical acceleration for ride comfort in active suspension systems}, journal = {Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering}, volume = {232}, year = {2018}, month = {12/2017}, pages = {223-232}, abstract = {

This article proposes a new adaptive control algorithm for active suspension systems of passenger cars. It combines a proportional-€“integral-€“derivative controller for suspension deflection together with a sliding mode reference conditioning outer loop that uses the vertical acceleration of the car body as a complementary source of control. The proposed approach is software-based and allows setting up limit values to critical variables, such as the vertical acceleration, which can be directly tuned by the system designer to range from the original proportional{\^a}€“integral{\^a}€“derivative response to other ones with tighter control on the constrained variable. A longitudinal half-car system subject to irregular excitation from a road surface is used for assessment. The proposed proportional{\^a}€“integral{\^a}€“derivative with sliding mode reference conditioning is compared to the same proportional{\^a}€“integral{\^a}€“derivative controller without the outer conditioning loop, as well as with a passive suspension system. International standards on overall vibration magnitudes are used to quantify the differences obtained in this assessment. Results obtained from the proposed control system show better performance and handle trade-offs, improving the ride comfort without adversely affecting the road holding of the car.

}, doi = {10.1177/0959651817745469}, author = {Le{\'o}n-Vargas, Fabi{\'a}n and Garelli, Fabricio and Zapateiro, Mauricio} } @article {247, title = {A novel PV-MPPT method based on a second order sliding mode gradient observer}, journal = {Energy Conversion and Management}, volume = {176}, year = {2018}, pages = {422 - 430}, abstract = {

Leading PV system operation at its Maximum Power Point (MPP) is crucial to improve the overall system efficiency and reduce the solar energy cost. In such a sense, this paper presents a closed-loop Maximum Power Point Tracking (MPPT) method based on the combination of a Second Order Sliding Mode Observer (SOSMO) and a traditional PI controller. The particular SOSMO proposed is especially appropriate to deal with finite time power gradient estimation even in the presence of unmodeled dynamics and external perturbations. Based on this estimation, the PI controller is used to quickly drive the PV system to operate on its MPP and tracking its variations. The resulting closed-loop scheme presents a fast tracking dynamics during rapidly changing environmental conditions having good accuracy and a moderate computational burden. The closed-loop system performance is evaluated using representative computer simulations and corroborated through experimental tests.

}, issn = {0196-8904}, doi = {https://doi.org/10.1016/j.enconman.2018.09.018}, url = {https://authors.elsevier.com/c/1XmVGin8VSMlu}, author = {Valenciaga, Fernando and Inthamoussou, Fernando A.} } @article {233, title = {Open-loop glucose control: Automatic IOB-based Super-Bolus feature for commercial insulin pumps}, journal = {Computer Methods and Programs in Biomedicine}, volume = {159}, year = {2018}, pages = {145 - 158}, abstract = {

Background and Objective: Although there has been significant progress towards closed-loop type 1 diabetes mellitus (T1DM) treatments, most diabetic patients still treat this metabolic disorder in an open-loop manner, based on insulin pump therapy (basal and bolus insulin infusion). This paper presents a method for automatic insulin bolus shaping based on insulin-on-board (IOB) as an alternative to conventional bolus dosing.

Methods: The methodology presented allows the pump to generate the so-called super-bolus (SB) employing a two-compartment {\.I}OB dynamic model. The extra amount of insulin to boost the bolus and the basal cutoff time are computed using the duration of insulin action (DIA). In this way, the pump automatically re-establishes basal insulin when {\.I}OB reaches its basal level. Thus, detrimental transients caused by manual or a-priori computations are avoided.

Results: The potential of this method is illustrated via in-silico trials over a 30 patients cohort in single meal and single day scenarios. In the first ones, improvements were found (standard treatment vs. automatic SB) both in percentage time in euglycemia (75g meal: 81.9 +- 15.59 vs. 89.51 +- 11.95, rho approx 0; 100g meal: 75.12 +- 18.23 vs. 85.46 +- 14.96, rho approx. 0) and time in hypoglecymia (75g meal: 5.92 +- 14.48 vs. 0.97 +- 4.15, rho = 0.008 ; 100g meal: 9.5 +-17.02 vs. 1.85 +- 7.05, rho = 0.014 ). In a single day scenario, considering intra-patient variability, the time in hypoglycemia was reduced (9.57 +- 14.48 vs. 4.21 +- 6.18, rho = 0.028 ) and improved the time in euglycemia (79.46 +- 17.46 vs. 86.29 +- 11.73, rho = 0.007 ).

Conclusions: The automatic IOB-based SB has the potential of a better performance in comparison with the standard treatment, particularly for high glycemic index meals with high carbohydrate content. Both glucose excursion and time spent in hypoglycemia were reduced.

}, issn = {0169-2607}, doi = {https://doi.org/10.1016/j.cmpb.2018.03.007}, author = {Rosales, Nicol{\'a}s and De Battista, Hern{\'a}n and Veh{\'\i}, Josep and Garelli, Fabricio} } @article {240, title = {Optimal sizing of a grid-assisted wind-hydrogen system}, journal = {Energy Conversion and Management}, volume = {166}, year = {2018}, pages = {402 - 408}, abstract = {

Hydrogen obtained from water electrolysis in addition to being sustainable becomes commercially competitive when a high degree of purity is sought. Ideally such purity is achieved by keeping the electrolyzer on a constant and rated power. To satisfy this objective the assistance of the electric grid to deal with the variability of the wind resource was proposed. The disadvantage of this alternative is the failure to ensure a 100\% carbon-emission-free hydrogen. The surplus wind energy can be delivered to the grid to optimize the trade-off between purity and cleaning degree. This paper presents a study on how the electrolyzer should be sized {\^a}€“ according to the turbine and wind resource {\^a}€“ to fully compensate these emissions along the year, that is, to cancel the annual power supplied by the grid.

}, issn = {0196-8904}, doi = {https://doi.org/10.1016/j.enconman.2018.04.047}, author = {Garc{\'\i}a-Cl{\'u}a, Jos{\'e} G. and Mantz, Ricardo J. and De Battista, Hern{\'a}n} } @conference {253, title = {Power Schedule for a Hydro-Wind System Based on a Predictive Algorithm}, booktitle = {2018 Argentine Conference on Automatic Control (AADECA)}, year = {2018}, month = {Nov}, abstract = {

This article presents an alternative to the traditional power dispatch policy, that includes a predictive controller in the hourly pre-dispatch layer. This approach allows the consideration of previous measurements, like wind resource, in order to improve the planning performance. The proposed control layer is applied to a reservoir hydropower plant and a wind farm operation in a weak network. The proposed controller aims to increase wind penetration while supplying energy demand and maintained reservoir level within normal operation. The results obtained through the use of real data show that, with an adequate prediction horizon, wind penetration can be increased in the system.

}, doi = {10.23919/AADECA.2018.8577352}, author = {Levieux, Luis I. and Ocampo-Mart{\'\i}nez, Carlos and Inthamoussou, Fernando A. and De Battista, Hern{\'a}n} } @article {264, title = {Study of the reverse saturation current and series resistance of p-p-n perovskite solar cells using the single and double-diode models}, journal = {Superlattices and Microstructures}, volume = {123}, year = {2018}, pages = {338 - 348}, abstract = {

The effects of the offset level and of the doping level in the perovskite layer upon both the reverse saturation current (J0) and the series resistance (Rs) of p-p-n perovskite solar cells have been researched in this paper, using five different materials such as spiro-OMeTAD, Cu2O, CuSCN, NiO and CuI, as Hole Transporting Material (HTM). The analysis was carried out by means of the single and double-diode models of a solar cell and of genetic algorithms based on optimization technique, in order to extract the desired parameters. The minor degradation of J0 and Rs has been found for the condition offset equal to zero and for the highest doping level in p-type perovskite layer. Also, a comparison has been made of the behavior of two reverse saturation currents (J01 and J02). The power conversion efficiency (PCE) has shown to be more strongly dependent on J02 than on J01. Results obtained in this work can be used to improve the manufacturing process of these devices.

}, keywords = {Genetic algorithm, Hole Transporting Material (HTM), One and two-diode models, Parameters extraction, Perovskite solar cells}, issn = {0749-6036}, doi = {https://doi.org/10.1016/j.spmi.2018.09.023}, url = {http://www.sciencedirect.com/science/article/pii/S0749603618314241}, author = {Cappelletti, Marcelo and Casas, G. and C{\'e}dola, A. and Peltzer y Blanc{\'a}, E. and Mar{\'\i} Soucase, B.} } @conference {248, title = {Analysis of the coordinated operation of a hydroelectric power plant and a wind farm in Patagonia}, booktitle = {2017 XVII Workshop on Information Processing and Control (RPIC)}, year = {2017}, month = {Sept}, abstract = {

In this work an analysis of the coordinated operation between the wind farm (WF) El Angelito and the hydroelectric power station Futaleuf{\'u}, located in Chubut, Argentina, is carried out. With a power of 200MW, El Angelito would be the largest WF in the country. With this new generation, the elements of the system will not be able to handle both sources at nominal power. In particular, there would be a bottleneck in the line where the WF would be connected and in the transformer that connects the system to 500kV. To avoid this situation, a coordinated operation of both generation sources is evaluated. In this way, a heuristic algorithm is analyzed to minimize the wind and hydraulic discharge, maximizing the power generation under restrictions in the transmission system. Three modes of operation were analyzed. The obtained results, simulated in a year with real data, show the benefits of the coordinated operation.

}, doi = {10.23919/RPIC.2017.8211643}, author = {Levieux, Luis I. and Inthamoussou, Fernando A. and De Battista, Hern{\'a}n} } @article {263, title = {Analysis of the power conversion efficiency of perovskite solar cells with different materials as Hole-Transport Layer by numerical simulations}, journal = {Superlattices and Microstructures}, volume = {107}, year = {2017}, pages = {136 - 143}, abstract = {

In this paper, a theoretical study of different p-p-n perovskite solar cells has been performed by means of computer simulation. Effects of the offset level upon the power conversion efficiency (PCE) of these devices have been researched using five different materials such as spiro-OMeTAD, Cu2O, CuSCN, NiO and CuI, as Hole Transporting Layer (HTL). The Solar Cells Capacitance Simulator (SCAPS)-1D has been the tool used for numerical simulation of these devices. A strong dependence of PCE has been found with the difference between the Maximum of the Valence Band of the HTL and perovskite materials, and with the doping level in p-type perovskite layer. A minimum value of hole mobility in the HTL has been also found, below which the PCE is reduced. Efficiencies in the order of 28\% have been obtained for the Cu2O/Perovskite/TiO2 solar cell. Results obtained in this work show the potentiality of this promising technology.

}, keywords = {Hole Transporting Layer (HTL), Numerical simulation, Perovskite, Solar energy}, issn = {0749-6036}, doi = {https://doi.org/10.1016/j.spmi.2017.04.007}, url = {http://www.sciencedirect.com/science/article/pii/S0749603617303087}, author = {Casas, G. and Cappelletti, Marcelo and C{\'e}dola, A. and Mar{\'\i} Soucase, B and Peltzer y Blanc{\'a}, E.} } @article {236, title = {Artificial Pancreas: First Clinical Trials in Argentina}, journal = {IFAC-PapersOnLine}, volume = {50}, year = {2017}, pages = {7731 - 7736}, abstract = {

The first clinical trials using an Artificial Pancreas (AP) in Latin America have been defined in 2 stages. The first stage was carried out in November 2016 with the UVA controller (developed by the Center for Diabetes Technology and already clinically tested), and the second will be performed during the first semester of 2017 with the ARG (Automatic Regulation of Glucose) algorithm (developed by ITBA, UNQ, and UNLP in Argentina). Both tests are based on the DiAs (Diabetes Assistant) from the UVA, and are performed in the HIBA on 5 patients with Type 1 Diabetes Mellitus (T1DM), for 36 hours. For the first stage, Open-Loop (OL) insulin boluses were applied before meals and patient{\^a}€™s physical activity was included. On the other hand, for the second stage, patients will not be involved in physical activity, but no OL insulin boluses will be injected before meals. In this work, experimental results from the first stage with the UVA controller, and preliminary results with the ARG control algorithm tested on the UVA/Padova simulator are presented. Due to the final paper deadline, the experimental results from the second stage are not included here, but will be presented at the IFAC World Congress.

}, issn = {2405-8963}, doi = {https://doi.org/10.1016/j.ifacol.2017.08.1151}, author = {S{\'a}nchez-Pe{\~n}a, Ricardo and Colmegna, Patricio and Grosembacher, L. and Breton, M. and De Battista, Hern{\'a}n and Garelli, Fabricio and Belloso, W. H. and Campos-N{\'a}nez, E. and Simonovich, V. and Beruto, V. and Scibona, P. and Chernavvsky, D.} } @article {183, title = {Closed-loop growth-rate regulation in fed-batch dual-substrate processes with additive kinetics based on biomass concentration measurement}, journal = {Journal of Process Control}, volume = {44}, year = {2016}, pages = {14 - 22}, abstract = {This paper deals with the design of feeding rates for dual-substrate fed-batch processes where the main control objective is the regulation of the microbial growth rate. To this end, feedback of the growth rate error is incorporated to a biomass proportional dual feeding law. A second-order sliding mode observer is used to estimate the growth rate, so that no additional sensors are required. Stability conditions are derived and robustness against several disturbances such as yield uncertainty, measurement errors and kinetic model mismatch is analytically and numerically evaluated. The advantages of the proposal include: minimal measurement requirements, regulation with fast convergence to the desired growth rate and reduced regulation error in the presence of disturbances.}, issn = {0959-1524}, doi = {http://dx.doi.org/10.1016/j.jprocont.2016.05.003}, author = {Nu{\~n}ez, Sebasti{\'a}n and Garelli, Fabricio and De Battista, Hern{\'a}n} } @article {186, title = {LPV-based active power control of wind turbines covering the complete wind speed range}, journal = {Renewable Energy}, volume = {99}, year = {2016}, pages = {996 - 1007}, abstract = {This paper focuses on the active power control of wind turbines. Modern grid codes increasingly demand active power control in order to guarantee utility grid stability under high wind energy penetration. Active power control provides capabilities to regulate wind power below rated, to maintain a power reserve, to indirectly regulate the grid frequency, etc. New controllers are necessary to tackle the extended operating modes and new objectives. This paper addresses the control problem using LPV techniques, since they are particularly suited to cope with the nonlinearities that arise along the extended operating region. The proposed controller was evaluated on a 5 MW wind turbine benchmark. For that purpose, very demanding and realistic testing scenarios were built using the FAST aeroelastic wind turbine simulator as well as standardized wind speed profiles. The proposed controller was compared with the gain scheduled PI traditionally used for wind turbine control and also with a gain scheduled ℋ $\infty$ controller. Finally, a comparative load analysis is presented with the aim of showing that the softer and lower pitch activity of the proposed controller decreases the extreme load events.}, keywords = {active power control}, issn = {0960-1481}, doi = {http://dx.doi.org/10.1016/j.renene.2016.07.064}, url = {http://www.sciencedirect.com/science/article/pii/S0960148116306796}, author = {Inthamoussou, Fernando A. and De Battista, Hern{\'a}n and Mantz, Ricardo J.} } @mastersthesis {215, title = {Modelizaci{\'o}n, monitoreo y control en procesos para producci{\'o}n de biopl{\'a}sticos}, year = {2016}, school = {Universidad Nacional de La Plata}, type = {PhD}, abstract = {

This thesis addresses the control and estimation problem in high cell density processes. As case of study the production of bioplastics via Cupriavidus necator is studied. Novel contributions to process modelling, monitoring and on line optimization are done. With the objective of giving a more realistic and precise process description, control oriented models are developed for the volume variations in high cell density processes. Specially, for those which are fed with concentrated media and in which intracellular products are stored. The models obtained are practical in the sense that there is no dependence with difficult to obtain parameters and are more precise than other models previously reported. For process monitoring, algorithms are developed to estimate the reaction rates of the process. Observers are proposed for each of the phases of the bioplastics production process. The estimation algorithms make use of the previously developed volume models and constitute an important contribution to process monitoring in restrictive conditions, such as the ones found in high cell density processes. Along with the design of the estimators, original contributions are made to error analysis, stability proofs and conditions on the algorithm gains to achieve given decay rates in the errors. Also, experimental validation of the estimators is provided. The on line optimization of the processes is given by the use of extremum seeking controllers whose purpose is to maximize the reaction rates at, a priori, unknown operating points. A novel non linear control scheme is proposed, including a gradient estimation which allows convergence to the optimum of an objective function (the substrate to reaction rate map). For the first time, stability conditions are given for this controller, including unstructured uncertainty. Also, conditions on the design gains are obtained. The proposed control scheme improves previously reported ones in convergence speed and the smoothness of the obtained reaction rates. Moreover, it is based on the use of sensors of feasible application to high cell density processes. The control algorithm is finally applied to the bioplastics production process, obtaining satisfactory results.

}, keywords = {bioprocess control observers biotechnology}, url = {http://sedici.unlp.edu.ar/handle/10915/59639}, author = {Jamilis, Mart{\'\i}n} } @article {165, title = {Product-based sliding mode observer for biomass and growth rate estimation in Luedeking{\textendash}Piret like processes}, journal = {Chemical Engineering Research and Design}, volume = {105}, year = {2016}, pages = {24 - 30}, abstract = {

The on-line estimation of non-measurable substances and key process variables is relevant for the real-time monitoring of the bioprocesses. This paper deals with the on-line estimation of microbial growth rate and biomass concentration based on measures of the product concentration. The algorithm does not require a model of the growth rate and it can be applied to batch, fed-batch and continuous processes. The proposed observer, which is based on second-order sliding mode ideas, provides smooth estimates with reduced-order error dynamics. It is also shown that in case of error in the product formation parameters, convergence to an error bound can be achieved. Numerical simulations under different operating conditions are provided and the estimates obtained for lactic acid production are contrasted with documented experimental data.

}, keywords = {Bioprocess monitoring}, issn = {0263-8762}, doi = {http://dx.doi.org/10.1016/j.cherd.2015.10.030}, url = {http://www.sciencedirect.com/science/article/pii/S0263876215004049}, author = {Nu{\~n}ez, Sebasti{\'a}n and Garelli, Fabricio and De Battista, Hern{\'a}n} } @mastersthesis {182, title = {Production, Characterization and Application of a biocatalyst for L-Phe reduction in food hydrolysates}, year = {2016}, school = {Universidad Nacional de La Plata}, type = {PhD thesis}, address = {La Plata, Buenos Aires, Argentina}, abstract = {This thesis addresses the study and development of a novel biotechnological method for the production of alternative ingredients or formulas for PKU patients. This methodology consists in the use of a biocatalyst, particularly, the enzyme L-Phenylalanine ammonia lyase (PAL, EC 4.3.1.25) from Rhodosporidium toruloides NBRC 0559. PAL catalyzes the non oxidative deamination of L-Phenylalanine into trans-cinnamic acid. This enzyme is applied in the current thesis for the reduction or deprivation of L-phenylalanine in commercially available protein hydrolysates. The methodology proposed consists of a first stage based on biocatalyst obtention. First, in order to enhance PAL activity, the components of the culture medium were optimized by using several experimental designs. After cultivation, the biocatalyst was obtained by two different strategies: a) catalytic cells containing PAL were recovered from culture medium and then permeabilized with the aim of using them as a microreactor; b) PAL extract obtained from cell disruption was purified using a standard protocol. In a second stage, the catalytic cells were immobilized by inclusion into polymers, using calcium alginate. This biocatalyst was compared with purified PAL immobilized by retention into cellulose membranes. In both cases the alternatives were characterized to determine its feasibility of use given its potential industrial application. Finally, in a third step, the selected biocatalyst was employed in the treatment of commercially available protein hydrolysates, as model of its application. As an alternative approach, partially purified PAL was evaluated for the intended propose. Under each treatment, we evaluated the need for pretreatment of substrates as well as the optimum operating conditions to achieve the highest reduction in the shortest time. From the obtained results, discussed in this thesis, it was demonstrated the feasibility of the proposed process for the reduction of L-Phe content in protein hydrolysates. These studies are the preliminary knowledge for the generation of substitutes or formulas for patients with PKU, using a biotechnological method. Future studies require a technological approach in a pilot scale to transfer this knowledge to local industry.}, url = {http://sedici.unlp.edu.ar/handle/10915/52475}, author = {Casta{\~n}eda, Mar{\'\i}a T.} } @article {308, title = {Sliding mode reference conditioning for path following applied to an AUV}, journal = {IFAC-PapersOnLine}, volume = {49}, year = {2016}, pages = {8-13}, abstract = {

This work presents a dynamic model for an autonomous underwater vehicle (AUV), a validation of this model together with the simulator obtained from its application and an implementation of sliding mode reference conditioning (SMRC). This last technique is proposed in order to follow a path at maximum speed with bounded errors in a dynamical framework, taking care of the saturation in systems actuators, resulting in an improvement of the path tracking time.

}, issn = {2405-8963}, doi = {https://doi.org/10.1016/j.ifacol.2016.10.314}, author = {Rosendo, Juan L. and Clement, Benoit and Garelli, Fabricio} } @article {211, title = {Smooth extremum-seeking control for fed-batch processes}, journal = {IFAC-PapersOnLine}, volume = {49}, year = {2016}, pages = {103 - 108}, abstract = {

Many biotechnological processes have optimal substrate concentrations where a maximum growth rate is achieved. In this work an extremum seeking controller and a gradient estimator are proposed to maximize the growth rate in fed-batch bioprocesses even when the substrate to growth rate map is unknown. Both the controller and estimator are obtained with high order sliding mode algorithms. Stability proofs are given, and tools to tune the algorithms in terms of bounds of the hessian of the map are derived. Simulation results that illustrate the performance of the controller are shown.

}, keywords = {extremum seeking}, issn = {2405-8963}, doi = {http://dx.doi.org/10.1016/j.ifacol.2016.07.224}, url = {http://www.sciencedirect.com/science/article/pii/S2405896316304311}, author = {Jamilis, Mart{\'\i}n and Garelli, Fabricio and De Battista, Hern{\'a}n} } @article {167, title = {Stabilisation of grid assistance for a renewable hydrogen generation system by min-projection strategy}, journal = {IET Control Theory \& Applications}, volume = {10}, year = {2016}, pages = {183 - 189}, abstract = {Control of grid assistance is proposed in this study for a renewable hydrogen generation system of simple and robust structure. Here, the grid connection serves the dual purpose of minimising the effect of wind power variations in the electrolyser supply as well as maximising the hydrogen production. To regulate the electrolyser current at its rated value, a cascade control scheme is posed. The feedback loop which commands the grid converter switching is of interest for the design. The min-projection strategy that stabilises a switched affine system is applied as the switching law. The analysis of switched equilibria and their stability is done by employing the concepts of Filippov inclusion and common Lyapunov function, respectively. The obtained theoretical results are corroborated by numerical simulation.}, doi = { 10.1049/iet-cta.2014.1327}, author = {Garc{\'\i}a-Cl{\'u}a, Jos{\'e} G. and Mantz, Ricardo J. and De Battista, Hern{\'a}n and Gallegos, Norma G.} } @article {262, title = {Study of the electrical parameters degradation of {GaAs} sub-cells for triple junction space solar cells by computer simulation}, journal = {Semiconductor Science and Technology}, volume = {31}, year = {2016}, month = {oct}, pages = {115020}, abstract = {

In this paper, a theoretical study of the electrical parameters degradation of different n-type GaAs sub-cells for InGaP/GaAs/Ge triple junction solar cells irradiated with 1 and 5 MeV electrons has been performed by means of computer simulation. Effects of base carrier concentration upon the maximum power point, short-circuit current, open circuit voltage, diffusion current, recombination current and series resistance of these devices have been researched using the displacement damage dose method, the one-dimensional PC1D device modeling program and a home-made numerical code based on genetic algorithms. The radiative recombination lifetime, damage constant for minority-carrier lifetime and carrier removal rate models for GaAs sub-cells have been used in the simulations. An analytical model has been proposed, which is useful to describe the radiation-induced degradation of diffusion current, recombination current and series resistance. Results obtained in this work can be used to predict the radiation resistance of solar cells over a wide range of energies.

}, doi = {10.1088/0268-1242/31/11/115020}, url = {https://doi.org/10.1088\%2F0268-1242\%2F31\%2F11\%2F115020}, author = {Cappelletti, Marcelo and Casas, G and Morales, D and Hasperue, W and Peltzer y Blanc{\'a}, E} } @article {184, title = {Glare by Light Emitting Diode (LED) vehicle traffic signals}, journal = {International Journal of Mechanical and Materials Engineering}, volume = {10}, year = {2015}, pages = {1{\textendash}9}, abstract = {Background: In this paper we analyze devices for traffic signals (traffic lights) with light-emitting diode (LED) technology. Methods: The traditional measurements of luminous intensity were complemented with the luminance analysis of the devices, evaluated for diverse angular fields. Besides, a subjective glare evaluation is presented. In the experience, signals with LEDs directly visible and signals with refractors are compared. Both signals were introduced in the visual field of 30 observers within a perceptive scene that simulated night vision conditions for a driver. The observers were later inquired about the experienced perturbation or discomfort sensation. Results: The obtained results show a significant increase in the punctual luminance as well as an evident perturbation and discomfort for the observers. Conclusions: This effect together with the relatively high degree of coherence of the color lights could result in new kinds of glares not considered in the current standards.}, issn = {2198-2791}, doi = {10.1186/s40712-014-0027-2}, author = {Ixtaina, Pablo and Presso, Matias and Rosales, Nicol{\'a}s and Marin, Gustavo H.} } @article {124, title = {Model-based scale-up methodology for aerobic fed-batch bioprocesses: application to polyhydroxybutyrate (PHB) production}, journal = {Bioprocess and Biosystems Engineering}, volume = {38}, year = {2015}, pages = {1179-1190}, abstract = {

This work presents a general model-based methodology to scale-up fed-batch bioprocesses. The idea behind this approach is to establish a dynamics hierarchy, based on a model of the process, that allows the designer to determine the proper scale factors as well as at which point of the fed-batch the process should be scaled up. Here, concepts and tools of linear control theory, such as the singular value decomposition of the Hankel matrix, are exploited in the context of process design. The proposed scale-up methodology is first described in a bioprocesses general framework highlighting its main features, key variables and parameters. Then, it is applied to a polyhydroxybutyrate (PHB) fed-batch bioreactor and compared with three empirical criteria, that are traditionally employed to determine the scale factors of these processes, showing the usefulness and distinctive features of this proposal. Moreover, this methodology provides theoretical support to a frequently used empirical rule: scale-up aerobic bioreactors at constant volumetric oxygen transfer coefficient. Finally, similar process dynamic behavior and PHB production set at the laboratory scale are predicted at the new operating scale, while it is also determined that is rarely possible to reproduce similar dynamic behavior of the bioreactor using empirical scale-up criteria. {\textcopyright} 2015 Springer-Verlag Berlin Heidelberg

}, issn = {1615-7591}, doi = {10.1007/s00449-015-1360-4}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84922384165\&partnerID=40\&md5=6cba033531c8aaa914b499c9c69b20dc}, author = {Monsalve-Bravo, Gloria M. and Garelli, Fabricio and Mozumder, Md Salatul Islam and Alvarez, Hern{\'a}n and De Battista, Hern{\'a}n} } @article {157, title = {Modeling and estimation of production rate for the production phase of non-growth associated high cell density processes}, journal = {Bioprocess and Biosystems Engineering}, volume = {38}, year = {2015}, pages = {1903-1914}, abstract = {This paper addresses the estimation of the specific production rate of intracellular products and the modeling of the bioreactor volume dynamics in high cell density fed-batch reactors. In particular, a new model for the bioreactor volume is proposed, suitable to be used in high cell density cultures where large amounts of intracellular products are stored. Based on the proposed volume model, two forms of a high order sliding mode observer are proposed. Each form corresponds to the cases with residual biomass concentration or volume measurement respectively. The observers achieve finite time convergence and robustness to process uncertainties as the kinetic model is not required. Stability proofs for the proposed observer are given. The observer algorithm is assessed numerically and experimentally.}, keywords = {Bioplastics, Estimation, high cell density, Observer, PHB, Sliding mode, Software sensor, volume model}, doi = {10.1007/s00449-015-1430-7}, author = {Jamilis, Mart{\'\i}n and Garelli, Fabricio and Mozumder, MSI and Casta{\~n}eda, Teresita and De Battista, Hern{\'a}n} } @article {178, title = {Multiple-input-multiple-output high-order sliding mode control for a permanent magnet synchronous generator wind-based system with grid support capabilities}, journal = {IET Renewable Power Generation}, volume = {9}, year = {2015}, pages = {925-934}, abstract = {This study presents a control design for a grid connected wind energy conversion system based on a gearless PMSG. The generation system structure comprises a three blade turbine, a 2 MW multi-pole PMSG and a full-scale back-to-back frequency converter linked to the utility grid. The proposed control scheme allows following dynamical specifications taking into account operational requirements and ancillary services imposed by the recent grid connection codes, that is, reactive power regulation and fault ride-through (FRT) capabilities. The control actions to be applied during normal grid operation are designed through second-order sliding mode techniques using a two-stage cascade structure. The multi-variable controller designed attains to regulate the active and reactive powers delivered to the grid, minimising the resistive losses into the generator and maintaining important internal variables into the desired range. This controller presents attractive advantages such as robustness against unmodelled dynamics and external perturbations, finite time convergence to the sliding surfaces and chattering mitigation. To endorse the controlled system with FRT capabilities, a switching control scheme based on voltage grid measurements is also proposed. The performance of the whole control approach is analysed through representative simulations which include parameter variations, external perturbations and three-phase voltage dips.}, keywords = {active power regulation, blade turbine, blades, chattering mitigation, control system synthesis, external perturbation, fault ride-through capability, frequency convertors, FRT capability, full-scale back-to-back frequency converter, gearless permanent magnet synchronous generator, grid connected wind energy conversion system, grid support capability, machine control, MIMO systems, multiple-input-multiple-output high-order sliding mode control design, multipole PMSG, multivariable control systems, multivariable controller design, permanent magnet generators, permanent magnet synchronous generator wind-based system, power convertors, power generation control, power generation faults, power grids, power system measurement, reactive power control, reactive power regulation, resistive loss minimization, second-order sliding mode technique, switching control scheme, synchronous generators, variable structure systems, voltage control, voltage measurement, wind power plants, wind turbines}, issn = {1752-1416}, doi = {10.1049/iet-rpg.2014.0417}, author = {Valenciaga, Fernando and Fern{\'a}ndez, Roberto. D.} } @article {125, title = {Postprandial response improvement via safety layer in closed-loop blood glucose controllers}, journal = {Biomedical Signal Processing and Control}, volume = {16}, year = {2015}, pages = {80-87}, abstract = {

Traditional type 1 diabetes therapies are prone to show poor glucose regulation especially in the postprandial period owing to both physiological and technological limitations. Although a closed-loop controller for glucose regulation has to be tuned to minimize the postprandial excursion and avoid late hypoglycemia, the intrinsic limitations of the problem lead to a trade-off between postprandial peak and late hypoglycemia risk. This paper reveals through an intensive in-silico study with multiple controller tuning combinations that a novel safety layer for glucose controllers, the so-called SAFE loop (Revert et al., 2013), not only reduces the hypoglycemia events but also allows reducing the postprandial glucose excursion, thus breaking the implicit trade-off present in single controllers. The SAFE outer loop monitors the estimated amount of insulin on board, and modifies the control action if it is close to a unique constraint which can be adjusted with clinical criteria. A very challenging test scenario is here implemented including the rate of blood glucose appearance from intakes of mixed meals, diurnal and day-to-day time-varying metabolic changes, inherent drawbacks in sensor and actuator, and other realistic conditions. The results show a significant reduction of hypoglycemia events when SAFE is added, regardless the closed-loop glucose controller, together with a potential postprandial response improvement.

}, doi = {10.1016/j.bspc.2014.10.003}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84910030806\&partnerID=40\&md5=23aa19a2b59e400d05ae30435b8b33e2}, author = {Le{\'o}n-Vargas, Fabi{\'a}n and Garelli, Fabricio and De Battista, Hern{\'a}n and Veh{\'\i}, Josep} } @article {181, title = {Reduction of l-phenylalanine in protein hydrolysates using l-phenylalanine ammonia-lyase from Rhodosporidium toruloides}, journal = {Journal of Industrial Microbiology \& Biotechnology}, volume = {42}, year = {2015}, pages = {1299{\textendash}1307}, abstract = {l-Phenylalanine ammonia-lyase (PAL, EC 4.3.1.25) from Rhodosporidium toruloides was utilized to remove l-phenylalanine (l-Phe) from different commercial protein hydrolysates. A casein acid hydrolysate (CAH, l-Phe~{\textasciitilde}2.28~\%) was employed as a model substrate. t-Cinnamic acid resulting from deamination of l-Phe was extracted, analyzed at ${\l}ambda$~=~290~nm, and used for PAL activity determination. Optimum reaction conditions, optimized using successive Doehlert design, were 35~mg~mL-1 of CAH and 800~mU~mL-1 of PAL, while temperature and pH were 42~{\textdegree}C and 8.7, respectively. Reaction kinetics of PAL with CAH was determined under optimized conditions. Then, removal of l-Phe from CAH was tested. Results showed that more than 92~\% of initial l-Phe was eliminated. Similar results were obtained with other protein hydrolysates. These findings demonstrate that PAL is a useful biocatalyst for l-Phe removal from protein hydrolysates, which can be evaluated as potential ingredients in foodstuffs for PKU patients.}, issn = {1476-5535}, doi = {10.1007/s10295-015-1664-z}, url = {http://dx.doi.org/10.1007/s10295-015-1664-z}, author = {Casta{\~n}eda, Mar{\'\i}a T. and Adachi, Osao and Hours, Roque A.} } @article {126, title = {Safety auxiliary feedback element for the artificial pancreas in type 1 diabetes}, journal = {Diabetes Technology and Therapeutics}, volume = {17}, year = {2015}, pages = {S35-S36}, doi = {10.1089/dia.2015.1504}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84923106010\&partnerID=40\&md5=c04d2504935658feaecb1cfccb49261c}, author = {Revert, Ana and Garelli, Fabricio and Pic{\'o}, Jes{\'u}s and De Battista, Hern{\'a}n and Rossetti, Paolo and Veh{\'\i}, Josep and Bondia, Jorge} } @article {117, title = {Specific growth rate observer for the growing phase of a Polyhydroxybutyrate production process}, journal = {Bioprocess and Biosystems Engineering}, volume = {38}, year = {2015}, pages = {557-567}, abstract = {

This paper focuses on the specific growth rate estimation problem in a Polyhydroxybutyrate bioplastic production process by industrial fermentation. The kinetics of the process are unknown and there are uncertainties in the model parameters and inputs. During the first hours of the growth phase of the process, biomass concentration can be measured online by an optical density sensor, but as cell density increases this method becomes ineffective and biomass measurement is lost. An asymptotic observer is developed to estimate the growth rate for the case without biomass measurement based on corrections made by a pH control loop. Furthermore, an exponential observer based on the biomass measurement is developed to estimate the growth rate during the first hours, which gives the initial condition to the asymptotic observer. Error bounds and robustness to uncertainties in the models and in the inputs are found. The estimation is independent of the kinetic models of the microorganism. The characteristic features of the observer are illustrated by numerical simulations and validated by experimental results.

}, keywords = {Bioplastics, Estimation, Observer, PHB, Software sensor}, issn = {1615-7591}, doi = {10.1007/s00449-014-1295-1}, url = {http://dx.doi.org/10.1007/s00449-014-1295-1}, author = {Jamilis, Mart{\'\i}n and Garelli, Fabricio and Mozumder, Md Salatul Islam and Volcke, Eveline and De Battista, Hern{\'a}n} } @mastersthesis {146, title = {Estimation and Control of Multivariable Biotechnological Processes}, volume = {PhD}, year = {2014}, month = {02/2015}, school = {Universidad Nacional de La Plata}, type = {PhD}, address = {La Plata, Buenos Aires, Argentina}, abstract = {La presente tesis doctoral aborda problemas de estimaci{\'o}n y control de variables en procesos biotecnol{\'o}gicos. Se aportan soluciones novedosas a dos cuestiones relevantes para el control de estos procesos: i) el dise{\~n}o de observadores (sensores virtuales) de variables no medibles a partir de las mediciones disponibles, y ii) el dise{\~n}o de lazos de regulaci{\'o}n del crecimiento en cultivos de microorganismos que utilizan m{\'u}ltiples sustratos. Con el objetivo de disponer de estimaciones de variables importantes del proceso que no son accesibles en l{\'\i}nea, se dise{\~n}an observadores que utilizan informaci{\'o}n de la din{\'a}mica de las variables medidas. En primer lugar se proponen observadores por modo deslizante para procesos en los que s{\'o}lo es medible la concentraci{\'o}n de producto. En este caso se estiman, con din{\'a}mica de error reducida, la tasa de crecimiento y la concentraci{\'o}n de biomasa, dos variables que son muy importantes para el monitoreo de los cultivos. Luego se presenta un observador por modo deslizante de segundo orden capaz de estimar m{\'u}ltiples tasas de formaci{\'o}n y consumo de sustancias a partir de medir la concentraci{\'o}n de estas sustancias. En este caso se obtiene convergencia en tiempo finito. Esto permite considerar las estimaciones obtenidas para la implementaci{\'o}n de lazos de realimentaci{\'o}n, donde la ventaja es que no se agrega din{\'a}mica adicional del observador. La segunda parte de la tesis trata problemas de regulaci{\'o}n en el contexto de procesos alimentados con m{\'u}ltiples sustratos. Se dise{\~n}a un algoritmo supervisor basado en modo deslizante cuyo objetivo es evitar que un sustrato necesario para el crecimiento alcance concentraciones que comprometan la operaci{\'o}n deseada del proceso. En particular se considera un proceso aer{\'o}bico con regulaci{\'o}n de la tasa de crecimiento, donde el ox{\'\i}geno disuelto es un sustrato necesario para el crecimiento microbiano y cuya disminuci{\'o}n puede llevar a respuestas indeseadas, tanto en el lazo de control de alimentaci{\'o}n como en el comportamiento del microorganismo. Finalmente, se realiza el dise{\~n}o de leyes de flujo proporcionales a la biomasa para cultivos semi-continuos alimentados con dos sustratos, donde el objetivo de control es la regulaci{\'o}n de la tasa de crecimiento total. La incorporaci{\'o}n del error de regulaci{\'o}n en la tasa de crecimiento permite mejorar el desempe{\~n}o del proceso. Se realiza adem{\'a}s la extensi{\'o}n de las leyes de alimentaci{\'o}n a modelos que incorporan el efecto de inhibici{\'o}n competitiva entre los sustratos. Estos modelos tienen particular relevancia, entre otras aplicaciones, en los procesos de biorremediaci{\'o}n de sustancias t{\'o}xicas.}, url = {http://sedici.unlp.edu.ar/handle/10915/44031}, author = {Nu{\~n}ez, Sebasti{\'a}n} } @inbook {82, title = {Gain Scheduled Hinf Control of Wind Turbines for the Entire Operating Range}, booktitle = {Wind Turbine Control and Monitoring}, year = {2014}, pages = {71{\textendash}95}, publisher = {Springer International Publishing}, organization = {Springer International Publishing}, abstract = {

Two different operating modes can be clearly identified in wind turbine control systems. In low wind speeds, the main control objective is the energy capture maximization, whereas in high wind speeds it is desired to regulate turbine power and speed at their rated values. The fulfillment of these different control objectives implies the transition through low controllability operating conditions that impose severe constraints on the achievable performance. The control task is usually tackled using two separate controllers, one for each operating mode, and a switching logic. Although satisfactory control solutions have been developed for low and high wind speeds, controller design needs refinement in order to improve performance in the transition zone. This chapter overviews a control scheme covering the entire operating range with focus on the transition zone. Hinf and advanced anti-windup techniques are exploited to design a high performance control solution for both operating modes with optimum performance in the transition zone.

}, keywords = {Anti-windup - Gain-scheduling control - Hinf optimal control - Robust control - Wind turbines control}, doi = {10.1007/978-3-319-08413-8}, url = {http://link.springer.com/book/10.1007/978-3-319-08413-8}, author = {Inthamoussou, Fernando A. and Bianchi, Fernando D. and De Battista, Hern{\'a}n and Mantz, Ricardo J.} } @article {77, title = {Linear parameter-varying control of permanent magnet synchronous generators for wind power systems}, journal = {IET Power Electronics}, volume = {7}, year = {2014}, month = {March}, pages = {692-704(12)}, abstract = {

This study presents an optimal control strategy for the electronic interface of a wind energy conversion system based on a permanent magnet synchronous generator (PMSG). A linear optimal control is used on the grid side of the interface to ensure a proper power transfer and a linear parameter-varying (LPV) control on the machine side to cope with the wide operating conditions demanded by the wind turbine applications. The dynamics of a PMSG working in a variable speed wind turbine is affected by the rotational speed of the wind rotor. The LPV control uses the generator speed as a scheduling variable to adapt itself to different operating conditions. The proposed scheme results in a multi-variable self-scheduled controller with a PI structure similar to classical approaches. Thus, the control ensures performance and stability in all possible operating conditions whereas the implementation and the numerical stability are similar to previous schemes. The proposed control has been implemented in a test bench that includes a fully-rated back-to-back converter. The experimental results show a good performance in different scenarios in which the controller has to adapt itself to highly varying operating conditions.

}, keywords = {electronic interface, fully-rated back-to-back converter, generator speed, interface grid side, linear optimal control, linear parameter-varying control, LPV control, multivariable self-scheduled controller, numerical stability, optimal control strategy, permanent magnet synchronous generators, PI structure, PMSG dynamics, power transfer, scheduling variable, variable speed wind turbine, wind energy conversion system, wind power systems, wind rotor rotational speed, wind turbine application}, issn = {1755-4535}, doi = {10.1049/iet-pel.2013.0149}, url = {http://digital-library.theiet.org/content/journals/10.1049/iet-pel.2013.0149}, author = {Trilla, Llu{\'\i}s and Bianchi, Fernando D. and Gomis-Bellmunt, Oriol} } @article {46, title = {LPV Wind Turbine Control With Anti-Windup Features Covering the Complete Wind Speed Range}, journal = {Energy Conversion, IEEE Transactions on}, volume = {29}, year = {2014}, month = {March}, pages = {259-266}, abstract = {

This paper addresses the control of a variable-speed variable-pitch wind turbine in the whole wind speed range. To this end, a linear parameter varying anti-windup (AW) controller is proposed as part of a control structure focused on improving the transition between low- and high-wind speed operations. The control structure is similar to classical PI controls used in commercial wind turbines. However, a more advanced gain-scheduled controller and AW compensation are proposed. As a consequence, the new control scheme is capable of improving the behavior of the wind turbine in the transition zone and provides better stability margins. The proposed control was evaluated in a 5-MW wind turbine benchmark and compared with a classical control scheme. To this end, very demanding and realistic testing scenarios were built using the FAST aeroelastic wind turbine simulator as well as standardized wind speed profiles.

}, keywords = {Anti-windup, anti-windup features, benchmark, control of wind turbines, gain-scheduling control, Generators, linear parameter varying anti-windup controller, linear parameter varying systems, LPV wind turbine control, PI controls, power system control, Proposals, Torque, variable-speed variable-pitch wind turbine, Velocity control, Wind speed, wind speed range, wind turbines}, issn = {0885-8969}, doi = {10.1109/TEC.2013.2294212}, author = {Inthamoussou, Fernando A. and Bianchi, Fernando D. and De Battista, Hern{\'a}n and Mantz, Ricardo J.} } @article {121, title = {Robot coordination using task-priority and sliding-mode techniques}, journal = {Robotics and Computer-Integrated Manufacturing}, volume = {30}, year = {2014}, pages = {74 - 89}, abstract = {

In this work, an approach based on task-priority redundancy resolution and sliding mode ideas is proposed for robot coordination. In particular, equality and inequality constraints representing the coordination of the multi-robot system are considered as mandatory (for instance, rigid-body manipulation constraints to distance between the end-effectors of several robot arms, or other inequality constraints guaranteeing safe operation of a robotic swarm or confining the robot{\textquoteright}s workspace to avoid collision and joint limits). Besides the mandatory constraints, other constraints with lower priority are considered for the tracking of the workspace reference and to achieve secondary goals. Thus, lower-priority constraints are satisfied only in the null space of the higher-priority ones. The fulfillment of the constraints is achieved using geometric invariance and sliding mode control theory. The validity and effectiveness of the proposed approach are substantiated by 2D and 3D simulation results using two 3R planar robots and two 6R PUMA-762 robots, respectively.

}, keywords = {Collision avoidance}, issn = {0736-5845}, doi = {http://dx.doi.org/10.1016/j.rcim.2013.08.003}, url = {http://www.sciencedirect.com/science/article/pii/S0736584513000598}, author = {Gracia, Luis and Sala, Antonio and Garelli, Fabricio} } @article {76, title = {A Second Order Sliding Mode Path Following Control for Autonomous Surface Vessels}, journal = {Asian Journal of Control}, volume = {16}, year = {2014}, pages = {1515{\textendash}1521}, abstract = {

This paper presents a path following control design for an autonomous surface vessel. The boat considered presents three degrees of freedom being driven by two independent propellers placed at its stern and is represented by a highly nonlinear underactuated dynamic model. The control objective is to reach and closely follow a pre-specified trajectory, operating in an environment perturbed by currents and waves. This objective is achieved through a control scheme based on the interaction of guidance laws synthesized by Lyapunov techniques and a high order sliding mode control approach based on the Super Twisting Algorithm. This methodology allows designing robust and simple controllers that avoid chattering effects on sliding surfaces, producing continuous control actions and presenting a reduced computational burden. The control performance is analyzed through representative simulations.

}, keywords = {Autonomous surface vessels, high order sliding mode, path following control, underactuated systems}, issn = {1934-6093}, doi = {10.1002/asjc.840}, url = {http://dx.doi.org/10.1002/asjc.840}, author = {Valenciaga, Fernando} } @article {45, title = {Second-order sliding mode observer for biomass concentration and growth rate estimation in batch photo-bioreactors}, journal = {International Journal of Hydrogen Energy}, volume = {39}, year = {2014}, pages = {8772 - 8779}, abstract = {

Abstract In this work the problem of estimating some variables of interest for monitoring and control of photo-fermentation processes is addressed. The focus is on a batch cultivation of Rhodobacter capsulatus where biohydrogen production rate is represented by a Luedeking{\^a}{\texteuro}{\textquotedblleft}Piret expression. The use of second-order sliding mode algorithms to estimate biomass concentration and bacterial specific growth rate is explored. It is concluded that the proposed observer does not require a kinetic model, thus eliminating a source of uncertainty. Also, it is shown that the error dynamics converges exponentially with short time constant determined by process parameters. Numerical simulations corroborate the convergence properties of the algorithm in the nominal case, as well as its robustness against parametric uncertainty and its performance under noisy measurement.

}, keywords = {Biohydrogen}, issn = {0360-3199}, doi = {http://dx.doi.org/10.1016/j.ijhydene.2013.12.033}, url = {http://www.sciencedirect.com/science/article/pii/S0360319913029662}, author = {Nu{\~n}ez, Sebasti{\'a}n and Garelli, Fabricio and De Battista, Hern{\'a}n} } @article {120, title = {Sufficient conditions for state observability in multi-substrate bioprocesses with additive growth dynamics}, journal = {Latin America Transactions, IEEE (Revista IEEE America Latina)}, volume = {12}, year = {2014}, month = {Aug}, pages = {928-934}, abstract = {

The distinguishability of the non-measured states is relevant for the design and implementation of state observers. The aim of this study is to examine the observability of a fed-batch multi-substrate process with additive growth rate. Based on the model equations, sufficient conditions to fulfill the observability rank condition were determined. Results for three sets of outputs were analyzed for Monod and Haldane models.

}, keywords = {Haldane models, Monod models, observability, observers}, issn = {1548-0992}, doi = {10.1109/TLA.2014.6872908}, author = {Nu{\~n}ez, Sebasti{\'a}n and De Battista, Hern{\'a}n and Garelli, Fabricio and Pic{\'o}, Jes{\'u}s} } @mastersthesis {148, title = {Switched Control Strategies. Application to Renewable Energy Conversion Systems and their Interaction with Power Grid}, volume = {PhD}, year = {2014}, month = {12/2014}, school = {Universidad Nacional de La Plata}, type = {PhD thesis}, address = {La Plata, Buenos Aires, Argentina}, abstract = {This thesis analyzes and proposes robust and flexible control strategies for renewable energy conversion systems in the distributed generation framework. It mainly deals with wind and photovoltaic energy conversion, and also with a storage and recovery energy system. Particular attention is given to the control of the micro source power supply in order to accomplish requirements for the connection to a distributed grid or a microgrid. The analysis of these power systems is out of the scope of this work. For photovoltaic energy systems, strategies for maximization of the resource extraction and control of the active power delivered by the micro source are proposed. A stability analysis for classical dc-dc converters is realized. Furthermore, these concepts are extended to the control of the electronic converter of fuel cell based micro sources. As for the storage and recovery energy system, a strategy capable of starting the system, exchanging energy with the grid, protecting the energy storage device and shutting down the system in a automatic way is proposed. The stability analysis of all operating modes and the combination among them for a global stable operation is performed. As for wind energy conversion systems, the operation of the wind turbine over the entire operating wind speed range is investigated. The operating region is extended to deal with active output power control which enables new operating modes like power generation with reserve for the contribution to frequency stability. The control of the electric interfaces is addressed in the sliding mode framework, whereas the H$\infty$ optimal control and the linear parameter varying (LPV) approach are used for the control of the mechanical actuators of wind turbines. Additionally, for PV, fuel cell and storage systems, simulation and experimental results are presented. As for wind turbine systems, simulation results with a high order model (FAST) developed by the National Renewable Energy Laboratory (NREL) are presented. The obtained results confirms the performance and feasibility of the proposed strategies predicted by the theoretical analysis.}, url = {http://sedici.unlp.edu.ar/handle/10915/43189}, author = {Inthamoussou, Fernando A.} } @article {85, title = {Active and Reactive Power Control for Wind Turbine Based on a MIMO 2-Sliding Mode Algorithm With Variable Gains}, journal = {Energy Conversion, IEEE Transactions on}, volume = {28}, year = {2013}, month = {Sept}, pages = {682-689}, abstract = {

This study proposes a power control strategy for a grid-connected variable-speed wind turbine, based on a doubly-fed induction generator (DFIG) with slip power recovery. The control objectives vary with the zones of operation (dependant on the wind speed), aiming to maximize the active power in the partial load zone and to limit it when operating within the full load zone, while regulating the stator reactive power following grid requirements. The control design, based on the second-order sliding modes (SOSM) and Lyapunov, uses a modified version of the super-twisting algorithm with variable gains which can be applied to nonlinear multiple inputs-multiple outputs (MIMO) systems. The well-known robustness of the sliding techniques, the simplicity of the algorithm, and the adaptive characteristic of its gains are used together in this study to obtain a controller able to deal robustly with the exacting challenges presented by these systems. An additional benefit of the proposal lies in the smoothness of the control action, an important issue regarding applied mechanical efforts. Representative results obtained by simulation of the controlled system are shown and discussed.

}, keywords = {asynchronous generators, control design, DFIG, doubly-fed induction generator, energy conversion, full load zone, Gain, Lyapunov method, Mathematical model, MIMO, MIMO 2-sliding mode algorithm, MIMO communication, nonlinear multiple inputs-multiple outputs system, partial load zone, Power control, power generation control, power grid-connected variable-speed wind turbine, power grids, reactive power control, Rotors, second-order sliding modes, second-order sliding modes (SM), slip power recovery, SOSM, stator reactive power control strategy, Stators, super-twisting algorithm, variable gains, variable structure systems, Wind power generation, Wind speed, wind turbines}, issn = {0885-8969}, doi = {10.1109/TEC.2013.2272244}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=6582571}, author = {Evangelista, Carolina A. and Valenciaga, Fernando and Puleston, Pablo F.} } @article {123, title = {Control of a Supercapacitor Energy Storage System for Microgrid Applications}, journal = {Energy Conversion, IEEE Transactions on}, volume = {28}, year = {2013}, month = {Sept}, pages = {690-697}, abstract = {

The proper operation of a microgrid requires storage devices that increase the inertia and avoid instability of the system. This paper presents the control of an energy storage system (ESS) based on supercapacitor in the context of grid-connected microgrids. The ESS is composed of AC/DC and DC/DC converters tied by a dc link. A single sliding mode strategy is proposed to control a bidirectional dc/dc converter, capable of working properly under all operating conditions. The switching devices are commanded by a single sliding function, dynamically shaped by references sent from the microgrid central controller. This feature facilitates the implementation and design of the control law and simplifies the stability analysis over the entire operating range. The effectiveness of the proposed control strategy is illustrated by experimental results.

}, keywords = {AC-DC converter, AC-DC power convertors, bidirectional DC-DC converter control, DC-DC power convertors, distributed power generation, Energy storage systems (ESS), ESS, experimental setup, grid connected microgrid application, microgrid central controller, microgrids, Nonlinear control, Power electronics, power generation control, power grids, power system interconnection, sliding function, Sliding mode control, sliding mode strategy, stability, stability analysis, supercapacitor energy storage system control, supercapacitors, switching convertors, switching device, variable structure systems}, issn = {0885-8969}, doi = {10.1109/TEC.2013.2260752}, author = {Inthamoussou, Fernando A. and Pegueroles-Queralt, Jordi and Bianchi, Fernando D.} } @article {47, title = {Decentralized Control with Minimum Dissolved Oxygen Guaranties in Aerobic Fed-Batch Cultivations}, journal = {Industrial \& Engineering Chemistry Research}, volume = {52}, year = {2013}, pages = {18014-18021}, abstract = {

In this work, a control strategy to guarantee a minimum dissolved oxygen concentration in aerobic fed-batch bioprocesses is proposed. The strategy is equally applicable to avoid low oxygen concentrations that might be detrimental for metabolites production, to prevent metabolic changes and to maintain an oxygen level in the culture compatible with the desired growth rate during the growing phase of the process. It essentially consists in adapting the set-point of the feeding controller to cope with faults and saturation in the oxygen regulation subsystem. The idea behind this adaptation is to manipulate, when necessary, the oxygen consumption in such a way that the oxygen in the culture is maintained above a prescribed threshold. The algorithm is based on sliding mode techniques, and its main features are as follows: simplicity, robustness to process uncertainties, easy implementation, and versatility to be combined with different dissolved oxygen and feeding controllers. The method is assessed numerically in a fed-batch growth phase of Pichia pastoris where an oxygen shortage leads to excessive glycerol accumulation.

}, doi = {10.1021/ie4021107}, url = {http://dx.doi.org/10.1021/ie4021107}, author = {Nu{\~n}ez, Sebasti{\'a}n and Garelli, Fabricio and De Battista, Hern{\'a}n} } @mastersthesis {155, title = {Hybrid Control Systems. Application to Hydrogen Generation from Renewable Energy Resources}, volume = {PhD}, year = {2013}, school = {Universidad Nacional de La Plata}, type = {PhD thesis}, address = {La Plata, Buenos Aires, Argentina}, abstract = {La presente tesis se orienta a la producci{\'o}n limpia de H2 a partir de sistemas de conversi{\'o}n de energ{\'\i}a solar y e{\'o}lica. Se analizan configuraciones de SGRHs (Sistemas de Generaci{\'o}n Renovable de Hidrog{\'e}no), aut{\'o}nomas y asistidas por red, cuyo objetivo principal es el suministro adecuado de potencia al electrolizador. El modelado, an{\'a}lisis de la din{\'a}mica y dise{\~n}o de control se efect{\'u}a aplicando conceptos de sistemas din{\'a}micos h{\'\i}bridos. Para describir apropiadamente la interacci{\'o}n entre variables continuas y discretas t{\'\i}pica de tales sistemas se emplea como herramienta matem{\'a}tica el aut{\'o}mata h{\'\i}brido.}, url = {http://sedici.unlp.edu.ar/handle/10915/30339}, author = {Garc{\'\i}a-Cl{\'u}a, Jos{\'e} G.} } @article {7, title = {Integrated sliding-mode algorithms in robot tracking applications}, journal = {Robotics and Computer-Integrated Manufacturing}, volume = {29}, year = {2013}, pages = {53 - 62}, abstract = {

An integrated solution based on sliding mode ideas is proposed for robotic trajectory tracking. The proposal includes three sliding-mode algorithms for speed auto-regulation, path conditioning and redundancy resolution in order to fulfill velocity, workspace and C-space constraints, respectively. The proposed method only requires a few program lines and simplifies the robot user interface since it directly deals with the fulfillment of the constraints to find a feasible solution for the robot trajectory tracking in a short computation time. The proposed approach is evaluated in simulation on the freely accessible 6R robot model PUMA-560, for which the main features of the method are illustrated.

}, keywords = {Sliding mode}, issn = {0736-5845}, doi = {10.1016/j.rcim.2012.07.007}, url = {http://www.sciencedirect.com/science/article/pii/S0736584512000919}, author = {Gracia, Luis and Garelli, Fabricio and Sala, Antonio} } @article {88, title = {Lyapunov-Designed Super-Twisting Sliding Mode Control for Wind Energy Conversion Optimization}, journal = {Industrial Electronics, IEEE Transactions on}, volume = {60}, year = {2013}, month = {Feb}, pages = {538-545}, abstract = {

This work explores an adaptive second-order sliding mode control strategy to maximize the energy production of a wind energy conversion system (WECS) simultaneously reducing the mechanical stress on the shaft. Such strategy successfully deals with the random nature of wind speed, the intrinsic nonlinear behavior of the WECS, and the presence of model uncertainties and external perturbations acting on the system. The synthesized adaptive controller is designed from a modified version of the super-twisting (ST) algorithm with variable gains. The suitability of the proposed strategy is proved by extensive computer-aided simulations employing a comprehensive model of the system emulating realistic conditions of operation, i.e., considering variations in the parameters and including external disturbances. Additionally, a second controller based on the traditional ST algorithm is also designed and simulated. Results are presented and discussed in order to establish a comparison framework.

}, keywords = {adaptive control, adaptive second-order control strategy, Algorithm design and analysis, CAD, Computational modeling, control system synthesis, Control systems, direct energy conversion, extensive computer-aided simulations, external disturbances, external perturbations, Generators, intrinsic nonlinear behavior, Lyapunov methods, Lyapunov-designed super-twisting sliding mode control, mechanical stress reduction, model uncertainties, Sliding mode control, ST algorithm, suitability strategy, super-twisting (ST), system emulating realistic conditions, Torque, variable gains, variable structure systems, WECS, wind energy conversion optimization, wind power, Wind power generation, Wind speed, wind turbines}, issn = {0278-0046}, doi = {10.1109/TIE.2012.2188256}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6153362}, author = {Evangelista, Carolina A. and Puleston, Pablo F. and Valenciaga, Fernando and Fridman, Leonid M.} } @article {49, title = {Postprandial blood glucose control using a hybrid adaptive PD controller with insulin-on-board limitation}, journal = {Biomedical Signal Processing and Control}, volume = {8}, year = {2013}, pages = {724 - 732}, abstract = {

Abstract This paper addresses the design of blood glucose control during the postprandial period for Type 1 diabetes patients. An artificial pancreas for ambulatory purposes has to deal with the delays inherent to the subcutaneous route, the carbohydrate intakes, the metabolic changes, the glucose sensor errors and noise, and the insulin pump constraints. A time response typically obtained in closed-loop insulin delivery shows hyperglycemia in the early postprandial period caused by the lag in the insulin absorbtion, followed by hypoglycemia caused by control over-reaction. A hybrid control system is proposed in this paper to overcome these problems. An insulin bolus is administered prior to the meals like in open-loop control, whereas a PD controller is used for robust glucose regulation. The controller gain is progressively increased after the bolus from zero up to its nominal value as function of the insulin on board, so that the PD controller becomes fully operational just when the insulin on board falls below a prescribed value. An excessive accumulation of active insulin is avoided in this way, drastically reducing the risk of hypoglycemia. The controller gain is adapted by means of a variable structure algorithm, allowing a very simple software implementation. The robust performance of the control algorithm is intensively assessed in silico on a cohort of virtual patients under challenging realistic scenarios considering mixed meals, circadian variations, time-varying uncertainties, discrete measurement and actuation, sensor errors and other disturbances.

}, keywords = {Artificial pancreas}, issn = {1746-8094}, doi = {http://dx.doi.org/10.1016/j.bspc.2013.06.008}, url = {http://www.sciencedirect.com/science/article/pii/S1746809413000931}, author = {Le{\'o}n-Vargas, Fabi{\'a}n and Garelli, Fabricio and De Battista, Hern{\'a}n and Veh{\'\i}, Josep} } @article {134, title = {Reactive Sliding-Mode Algorithm for Collision Avoidance in Robotic Systems}, journal = {Control Systems Technology, IEEE Transactions on}, volume = {21}, year = {2013}, month = {Nov}, pages = {2391-2399}, abstract = {

This brief presents a reactive reference conditioning algorithm for robot collision avoidance based on geometric invariance and sliding-mode (SM) ideas. First, constraints are defined in terms of the measurements given by the robot{\textquoteright}s sensors in order to guarantee that collisions will not occur. Then, a supervisory loop ensures the fulfillment of the constraints modifying the reference trajectory as much as necessary by means of a discontinuous control law. The proposed algorithm activates only when the constraints are about to be violated and, thus, in contrast to conventional SM approaches, there exists no reaching mode to the limit surface of the constraints (sliding surface). The validity and effectiveness of the proposed approach is substantiated by simulation and experimental results using a mobile robot equipped with infrared sensors.

}, keywords = {Collision avoidance, constraint limit surface, constraint violation, discontinuous control law, geometric invariance, infrared detectors, infrared sensors, mobile robot, mobile robots, Motion planning, reaching mode, reactive reference conditioning algorithm, reactive sliding-mode algorithm for collision avoidance in robotic systems, reference conditioning, reference trajectory, robot collision avoidance, Robot sensing systems, robot sensors, Sliding mode control, sliding surface, sliding-mode (SM) control, supervisory loop, trajectory control, variable structure systems}, issn = {1063-6536}, doi = {10.1109/TCST.2012.2231866}, author = {Gracia, Luis and Garelli, Fabricio and Sala, Antonio} } @article {50, title = {Safety Auxiliary Feedback Element for the Artificial Pancreas in Type 1 Diabetes}, journal = {Biomedical Engineering, IEEE Transactions on}, volume = {60}, year = {2013}, month = {Aug}, pages = {2113-2122}, abstract = {

The artificial pancreas aims at the automatic delivery of insulin for glycemic control in patients with type 1 diabetes, i.e., closed-loop glucose control. One of the challenges of the artificial pancreas is to avoid controller overreaction leading to hypoglycemia, especially in the late postprandial period. In this study, an original proposal based on sliding mode reference conditioning ideas is presented as a way to reduce hypoglycemia events induced by a closed-loop glucose controller. The method is inspired in the intuitive advantages of two-step constrained control algorithms. It acts on the glucose reference sent to the main controller shaping it so as to avoid violating given constraints on the insulin-on-board. Some distinctive features of the proposed strategy are that 1) it provides a safety layer which can be adjusted according to medical criteria; 2) it can be added to closed-loop controllers of any nature; 3) it is robust against sensor failures and overestimated prandial insulin doses; and 4) it can handle nonlinear models. The method is evaluated in silico with the ten adult patients available in the FDA-accepted UVA simulator.

}, keywords = {Absorption, Artificial, artificial organs, Artificial pancreas, Biological, Blood Glucose Self-Monitoring, closed loop systems, closed-loop glucose control, Computer Simulation, Computer-Assisted, Diabetes, Diabetes Mellitus, diseases, drug delivery systems, Drug Therapy, drugs, Equipment Safety, FDA-accepted UVA simulator, feedback, glucose control, glycemic control, Humans, hypoglycemia, insulin, insulin-on-board, medical control systems, Models, Pancreas, Physiological, postprandial period, Proposals, reference conditioning, Robustness, safety, safety auxiliary feedback element, sliding mode (SM), sliding mode reference conditioning, Sugar, two-step constrained control algorithms, Type 1, type 1 diabetes}, issn = {0018-9294}, doi = {10.1109/TBME.2013.2247602}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6463437}, author = {Revert, Ana and Garelli, Fabricio and Pic{\'o}, Jes{\'u}s and De Battista, Hern{\'a}n and Rossetti, Paolo and Veh{\'\i}, Josep and Bondia, Jorge} } @article {48, title = {Second-order sliding mode observer for multiple kinetic rates estimation in bioprocesses}, journal = {Control Engineering Practice}, volume = {21}, year = {2013}, pages = {1259 - 1265}, abstract = {

Abstract Specific kinetic rates are key variables regarding metabolic activity in bioprocesses. They are non-linear functions of concentrations and operating conditions and therefore of difficult access for process control. In this paper, a multiple kinetic rates observer based on second-order sliding mode ideas is proposed. The main difference with other proposals is that smooth estimates are achieved in finite-time without adding additional dynamics. The resulting estimator is robust against uncertainty in the model of the estimated variables. Experimental results from continuous fermentation of S. cerevisiae are presented, where microbial specific growth rate and net ethanol production rate are estimated.

}, keywords = {Bioprocess control}, issn = {0967-0661}, doi = {http://dx.doi.org/10.1016/j.conengprac.2013.03.003}, url = {http://www.sciencedirect.com/science/article/pii/S0967066113000488}, author = {Nu{\~n}ez, Sebasti{\'a}n and De Battista, Hern{\'a}n and Garelli, Fabricio and Vignoni, Alejandro and Pic{\'o}, Jes{\'u}s} } @article {133, title = {Sliding Mode Reference Coordination of Constrained Feedback Systems}, journal = {Mathematical Problems in Engineering}, year = {2013}, pages = {ID-764348, 11 pages}, abstract = {

This paper addresses the problem of coordinating dynamical systems with possibly different dynamics (e.g., linear and nonlinear, different orders, constraints, etc.) to achieve some desired collective behavior under the constraints and capabilities of each system. To this end, we develop a new methodology based on reference conditioning techniques using geometric set invariance and sliding mode control: the sliding mode reference coordination (SMRCoord). The main idea is to coordinate the systems references. Starting from a general framework, we propose two approaches: a local one through direct interactions between the different systems by sharing and conditioning their own references and a global centralized one, where a central node makes decisions using information coming from the systems references. In particular, in this work we focus in implementation on multivariable systems like unmanned aerial vehicles (UAVs) and robustness to external perturbations. To show the applicability of the approach, the problem of coordinating UAVs with input constraints is addressed as a particular case of multivariable reference coordination with both global and local configuration.

}, issn = {1563-5147}, doi = {10.1155/2013/764348}, author = {Vignoni, Alejandro and Garelli, Fabricio and Pic{\'o}, Jes{\'u}s} } @article {51, title = {Stability preserving maps for finite-time convergence: Super-twisting sliding-mode algorithm}, journal = {Automatica}, volume = {49}, year = {2013}, pages = {534 - 539}, abstract = {

The super-twisting algorithm (STA) has become the prototype of second-order sliding mode algorithm. It achieves finite time convergence by means of a continuous action, without using information about derivatives of the sliding constraint. Thus, chattering associated to traditional sliding-mode observers and controllers is reduced. The stability and finite-time convergence analysis have been jointly addressed from different points of view, most of them based on the use of scaling symmetries (homogeneity), or non-smooth Lyapunov functions. Departing from these approaches, in this contribution we decouple the stability analysis problem from that of finite-time convergence. A nonlinear change of coordinates and a time-scaling are used. In the new coordinates and time{\^a}{\texteuro}{\textquotedblleft}space, the transformed system is stabilized using any appropriate standard design method. Conditions under which the combination of the nonlinear coordinates transformation and the time-scaling is a stability preserving map are given. Provided convergence in the transformed space is faster than O(1/T) -where T is the transformed time- convergence of the original system takes place in finite-time. The method is illustrated by designing a generalized super-twisting observer able to cope with a broad class of perturbations.

}, keywords = {Bioprocess control}, issn = {0967-0661}, doi = {http://dx.doi.org/10.1016/j.conengprac.2013.03.003}, url = {http://www.sciencedirect.com/science/article/pii/S0967066113000488}, author = {Pic{\'o}, Jes{\'u}s and Pic{\'o}-Marco, Enric and Vignoni, Alejandro and De Battista, Hern{\'a}n} } @article {135, title = {Systems coordination: using geometric set invariance and sliding modes ideas}, journal = {Revista Iberoamericana de Autom{\'a}tica e Inform{\'a}tica Industrial RIAI}, volume = {10}, year = {2013}, pages = {390 - 401}, abstract = {

Among the possible meanings of the word, this paper will discuss coordinated action to refer to the act on references of systems to achieve some collective behavior desired but considering the constraints and capabilities of each system. To this end, we develop a new methodology based on conditioning techniques reference using geometric invariance sets and sliding mode control. From a general framework, we propose two approaches: a global centralized one and a local through interactions between different systems. The approach addresses the problem of coordinating dynamical systems with possibly different dynamics (e.g. linear and nonlinear, different orders, constraints, etc.).The main idea is to shape the systems local feasible references in order to keep them coordinated.To show the applicability of the approach, the problem of coordinating different dynamical systems with control saturations is addressed as a particular case with both global and local configuration.

}, keywords = {systems coordination geometric set invariance sliding modes multi-agents systems constrained control}, issn = {1697-7912}, doi = {http://dx.doi.org/10.1016/j.riai.2013.09.001}, author = {Vignoni, Alejandro and Garelli, Fabricio and Pic{\'o}, Jes{\'u}s} } @article {261, title = {Theoretical study of the maximum power point of n-type and p-type crystalline silicon space solar cells}, journal = {Semiconductor Science and Technology}, volume = {28}, year = {2013}, month = {mar}, pages = {045010}, abstract = {

The performance of crystalline silicon n+/p/p+\ and n+/n/p+\ solar cells under AM0 spectrum, irradiated with 1 MeV electrons at fluences below 1017\ cm-2\ has been analyzed by means of computer simulation. The software used, fully developed by the authors, solves numerically in one dimension under steady-state conditions, the Poisson and continuity equations self-consistently. The influence of constructive characteristics and different levels of hazardous environmental work conditions on the maximum power point of over 150 devices has been investigated. The study has allowed the authors to propose a useful analytical model related to the constructive characteristics of the device such as polarity, base resistivity and total thickness, with the aim of examining the electrical performance of Si space solar cells. Results presented in this paper are important in order to contribute to the design of radiation-hardened devices.

}, doi = {10.1088/0268-1242/28/4/045010}, url = {https://doi.org/10.1088\%2F0268-1242\%2F28\%2F4\%2F045010}, author = {Cappelletti, Marcelo and Casas, G. and C{\'e}dola, A. and Peltzer y Blanc{\'a}, E.} } @article {8, title = {Dynamic estimations of metabolic fluxes with constraint-based models and possibility theory}, journal = {Journal of Process Control}, volume = {22}, year = {2012}, chapter = {1946-1955}, abstract = {Living cells can be modelled by successively imposing known constraints that limit their behaviour, such as mass balances, thermodynamic laws or enzyme capacities. The resulting constraint-based models enclose all the functional states that the modelled cells may exhibit. Then, predictions can be obtained from the models in two main ways: adding experimental data to determine the state of cells at given conditions (MFA) or invoking an assumption of evolved optimal behaviour (FBA). Both MFA and FBA predictions are typically performed at steady state. However, it is easy to take extracellular dynamics into account. This work explores the benefits of using possibility theory to get these dynamic predictions. It will be shown that the possibilistic methods (a) provide rich estimates for time-varying fluxes and metabolite concentrations, (b) account for uncertainty and data scarcity, and (c) give predictions relaxing the optimality assumption of FBA. On the other hand, these methods could serve as basis for monitoring and fault detection systems in industrial bioprocesses.}, doi = {http://dx.doi.org/10.1016/j.jprocont.2012.09.001}, url = {http://www.sciencedirect.com/science/article/pii/S0959152412002181$\#$}, author = {Llaneras, Francisco and Sala, Antonio and Pic{\'o}, Jes{\'u}s} } @article {18, title = {Flexible power control of fuel cells using sliding mode techniques}, journal = {Journal of Power Sources}, volume = {205}, year = {2012}, pages = {281 - 289}, abstract = {

The energy conversion system considered in this work consists of a fuel cell connected to a DC-bus through a switching converter. Particularly, the paper deals with the control of the electrical variables of this system. The control problem is addressed using tools of variable structure systems theory. The dynamic behavior of the system is first analyzed. Then, sliding mode algorithms to control electrical variables according to different power management objectives are developed. Thus, different control strategies such as fuel cell voltage/current regulation, maximum power point tracking and/or load current regulation can be followed. After studying their stability properties, these algorithms are combined to achieve a globally stable control over the whole electrical operating locus of the fuel cell. Experimental results on a test circuit are presented.

}, keywords = {Fuel cells}, issn = {0378-7753}, doi = {10.1016/j.jpowsour.2012.01.012}, url = {http://www.sciencedirect.com/science/article/pii/S037877531200016X}, author = {Inthamoussou, Fernando A. and Mantz, Ricardo J. and De Battista, Hern{\'a}n} } @article {78, title = {Gain scheduled control based on high fidelity local wind turbine models}, journal = {Renewable Energy}, volume = {37}, year = {2012}, pages = {233 - 240}, abstract = {

A new design methodology of gain scheduled controllers for wind turbines is presented. The proposed methodology is intended to deal with multi-variable and high order models as those produced by high fidelity aeroelastic simulators. The methodology consists in interpolating the local controller outputs and does not require a uniform state definition either of the local controllers or of the linear models. This allows the design of each controller independently, an essential point in cases of high order models. An aeroelastic model of a typical commercial wind turbine is used to illustrate the methodology.

}, keywords = {Wind energy}, issn = {0960-1481}, doi = {http://dx.doi.org/10.1016/j.renene.2011.06.024}, url = {http://www.sciencedirect.com/science/article/pii/S0960148111003168}, author = {Bianchi, Fernando D. and S{\'a}nchez-Pe{\~n}a, Ricardo S. and Guadayol, M.} } @article {89, title = {Multivariable 2-sliding mode control for a wind energy system based on a double fed induction generator}, journal = {International Journal of Hydrogen Energy}, volume = {37}, year = {2012}, pages = {10070-10075}, abstract = {

The purpose of this paper is to present a control strategy using Multiple Input/Multiple Output (MIMO) Second Order Sliding Modes (SOSM) for a grid-connected variable-speed Wind Energy Conversion System (WECS). The latter is based on a Double Fed Induction Generator (DFIG) in a bidirectional configuration with slip power recovery. Its points of operation can be electronically controlled and, with them, two independent control objectives can be stated. Thus, a control is designed to maximize the energy captured from the wind and to regulate the stator reactive power, contributing to the compensation of the power factor according to grid requirements. The proposed technique can be applied to nonlinear MIMO systems and allows to make a separate design for each component of the controller. For these designs the Super- Twisting algorithm is employed in this work, which possesses excellent properties regarding simplicity of implementation and online operation, and robustness against uncertainties and external disturbances. Finally, representative simulation results are presented and analyzed. Copyright {\^A}{\textcopyright} 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84862183613\&partnerID=40\&md5=377df701a20108562f585d6ff46deaa7}, author = {Evangelista, Carolina A. and Valenciaga, Fernando and Puleston, Pablo F.} } @article {17, title = {New concept in maximum power tracking for the control of a photovoltaic/hydrogen system}, journal = {International Journal of Hydrogen Energy}, volume = {37}, year = {2012}, pages = {14951 - 14958}, abstract = {

For the sustainable production of clean H2, it is essential to optimize the capture and conversion of renewable energy. In this context, this paper presents a new technique to maximize the efficiency of a photovoltaic conversion system supplying an electrolyzer. Simple, efficient and low cost maximum power point tracking algorithms to optimize energy production are proposed for the three DC/DC electronic converter topologies typically used in photovoltaic and H2 applications. The method is based on energy balance concepts and exhibits certain analogies with maximum power tracking algorithms extensively used in wind turbines that do not require measurement of the primary energy source. The algorithm provides a reference to the current controller only requiring measurement of electrical variables and solar array temperature. The current controller is implemented using sliding mode strategies. Experimental and simulation results are provided showing the effectiveness and simplicity of the proposed method.

}, keywords = {Hydrogen production}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2012.01.176}, url = {http://www.sciencedirect.com/science/article/pii/S0360319912003217}, author = {Inthamoussou, Fernando A. and De Battista, Hern{\'a}n and Mantz, Ricardo J.} } @article {5, title = {Nonlinear PI control of fed-batch processes for growth rate regulation}, journal = {Journal of Process Control}, volume = {22}, year = {2012}, pages = {789 - 797}, abstract = {

This paper deals with the regulation of the biomass specific growth rate, which is an important goal in many fed-batch fermentation processes. The proposed control system is based on the minimal model paradigm, requiring only biomass and volume measurement along with some bounds on the reaction rate. The controller has the structure of a partial state feed-back with adjustable gain. An integral-proportional control algorithm is designed to adjust this gain. It is inspired in concepts of invariant control and system immersion. First, a nonlinear integral action that makes invariant a goal manifold defined by a reference model dynamics is developed. Then, a proportional output error feed-back is incorporated to the control law with the aim of fastening convergence. Stability is investigated in detail using Lyapunov functions. To implement the control law, an estimation of the growth rate is required like any other PI-like controller. Because of its strong convergence properties, a sliding observer that requires the same process information as the controller is used for this task, although conventional continuous observers can alternatively be used provided they are fast enough to preserve stability. Simulation results showing the transient response and robustness features of the controller under nominal and perturbed scenarios are presented.

}, keywords = {Fed-batch processes}, issn = {0959-1524}, doi = {10.1016/j.jprocont.2012.02.011}, url = {http://www.sciencedirect.com/science/article/pii/S0959152412000601}, author = {De Battista, Hern{\'a}n and Pic{\'o}, Jes{\'u}s and Pic{\'o}-Marco, Enric} } @article {16, title = {A path conditioning method with trap avoidance}, journal = {Robotics and Autonomous Systems}, volume = {60}, year = {2012}, pages = {862 - 873}, abstract = {

This work presents a sliding-mode method for robotic path conditioning. The proposal includes a trap avoidance algorithm in order to escape from trap situations, which are analogous to local minima in potential field-based approaches. The sliding-mode algorithm activates when the desired path is about to violate the robot workspace constraints, modifying it as much as necessary in order to fulfill all the constraints and reaching their limit surface at low speed. The proposed path conditioning algorithm can be used on-line, since it does not require a priori knowledge of the desired path, and improves the conventional conservative potential field-based approach in the sense that it fully exploits the robot workspace. The proposed approach can be easily added as an auxiliary supervisory loop to conventional robotic planning algorithms and its implementation is very easy in a few program lines of a microprocessor. The proposed path conditioning is compared through simulation with the conventional potential field-based approach in order to show the benefits of the method. Moreover, the effectiveness of the proposed trap avoidance algorithm is evaluated by simulation for various trap situations.

}, keywords = {Path planning}, issn = {0921-8890}, doi = {10.1016/j.robot.2012.01.009}, url = {http://www.sciencedirect.com/science/article/pii/S0921889012000218}, author = {Gracia, Luis and Sala, Antonio and Garelli, Fabricio} } @article {14, title = {Reaction rate reconstruction from biomass concentration measurement in bioreactors using modified second-order sliding mode algorithms}, journal = {Bioprocess and Biosystems Engineering}, volume = {35}, year = {2012}, pages = {1615-1625}, abstract = {

This paper deals with the estimation of unknown signals in bioreactors using sliding observers. Particular attention is drawn to estimate the specific growth rate of microorganisms frommeasurement of biomass concentration. In a recent article, notions of high-order sliding modes have been used to derive a growth rate observer for batch processes. In this paperwe generalize and refine these preliminary results. We develop a new observer with a different error structure to copewith other types of processes. Furthermore,we show that these observers are equivalent, under coordinate transformations and time scaling, to the classical super-twisting differentiator algorithm, thus inheriting all its distinctive features. The new observers{\textquoteright} family achieves convergence to timevarying unknown signals in finite time, and presents the best attainable estimation error order in the presence of noise. In addition, the observers are robust to modeling and parameter uncertainties since they are based on minimal assumptions on bioprocess dynamics. In addition, they have interesting applications in fault detection and monitoring. The observers performance in batch, fed-batch and continuous bioreactors is assessed by experimental data obtained from the fermentation of Saccharomyces Cerevisiae on glucose.

}, doi = {10.1007/s00449-012-0752-y}, author = {De Battista, Hern{\'a}n and Pic{\'o}, Jes{\'u}s and Garelli, Fabricio and Navarro, Jos{\'e} L.} } @article {19, title = {Sliding mode observer for biomass estimation in a biohydrogen production process}, journal = {International Journal of Hydrogen Energy}, volume = {37}, year = {2012}, pages = {10089 - 10094}, abstract = {

This work deals with the problem of estimation of biomass concentration and specific growth rate in a biohydrogen production process. A photo-fermentation process with the photosynthetic bacteria Rhodobacter capsulatus is considered. The reaction dynamics is represented with a Monod law while the hydrogen production rate is modeled with a Luedeking-Piret expression. A sliding mode observer is proposed and designed, which gives an estimate of both biomass concentration and specific growth rate from measurements of the produced hydrogen volume. The proposed observer is completely robust against the growth kinetic model, and it presents a first-order reduced dynamics. Numerical simulation results are presented for a batch biohydrogen production process.

}, keywords = {Biohydrogen}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2011.12.104}, url = {http://www.sciencedirect.com/science/article/pii/S0360319911027972}, author = {Nu{\~n}ez, Sebasti{\'a}n and Garelli, Fabricio and De Battista, Hern{\'a}n} } @article {15, title = {A supervisory loop approach to fulfill workspace constraints in redundant robots}, journal = {Robotics and Autonomous Systems}, volume = {60}, year = {2012}, pages = {1 - 15}, abstract = {

An approach based on geometric invariance and sliding mode ideas is proposed for redundancy resolution in robotic systems to fulfill configuration and workspace constraints caused by robot mechanical limits, collision avoidance, industrial security, etc. Some interesting features of the proposal are that: (1)\ it can be interpreted as a limit case of the classical potential field-based approach for collision avoidance which requires using variable structure control concepts, (2)\ it allows reaching the limit surface of the constraints smoothly, depending on a free design parameter, and (3)\ it can be easily added as a supervisory block to pre-existing redundancy resolution schemes. The algorithm is evaluated in simulation on a 6R planar robot and on the freely accessible 6R robot model PUMA-560, for which the main features of the method are illustrated.

}, keywords = {Sliding mode}, issn = {0921-8890}, doi = {10.1016/j.robot.2011.07.008}, url = {http://www.sciencedirect.com/science/article/pii/S0921889011001308}, author = {Gracia, Luis and Sala, Antonio and Garelli, Fabricio} } @book {87, title = {Advanced control for constrained processes and systems}, year = {2011}, publisher = {Institution of Engineering and Technology}, organization = {Institution of Engineering and Technology}, abstract = {

In this book, Garelli, Mantz and De Battista unify recently proposed control strategies in a generalized framework to deal with different kinds of constraints. The resulting control strategies are based on reference conditioning ideas, implemented by means of supervisory loops which employ discontinuous actions. Although design simplicity is a book priority, the use of well established variable structure systems theory and sliding mode related concepts for theoretical analysis make the book also rigorous and self-contained. The book aims at providing solutions which can be added to pre-existent control designs, and that allow using conventional control tools for the main loop design. Switching signals are always confined to the low-power side of the systems, so that the implementation of the control schemes results extremely easy, both analogously or digitally. The first part of the book (Part I) focuses on providing a description as simple as possible of the methodology to deal with systems constraints in SISO systems. It also illustrates the design and implementation of the developed techniques through several case studies. Part II is devoted to multivariable constrained control problems. Finally, the book presents an extremely simple algorithm for the reduction of the undesired effects caused by manual-automatic or controller switching in multivariable process control.

}, keywords = {Constrained dynamic decoupling, Dealing with constraints in SISO control, Improving decoupling in decentralized control, MIMO bumpless transfer, MIMO systems - Relevant tools for dynamic decoupling, Partial decoupling and non-minimum phase systems, SISO systems - Constraints in feedback systems, Some practical case studies}, url = {http://www.theiet.org/resources/books/control/constrained-processes.cfm}, author = {Garelli, Fabricio and Mantz, Ricardo J. and De Battista, Hern{\'a}n} } @article {21, title = {Evaluation of hydrogen production capabilities of a grid-assisted wind-{H2} system}, journal = {Applied Energy}, volume = {88}, year = {2011}, pages = {1857-1863}, abstract = {

This paper analyzes the operation of a grid-assisted wind power system dedicated to hydrogen production. Several operation modes are evaluated with the aim of establishing control strategies for different requirements such as optimum wind power capture, maximum H2 production rate and maximum clean H2 production. Each operation mode is achieved by specific control of the grid-side power electronic converter. The operation of the wind turbine, the electrolyzer and the electronic converter connected to a common DC-bus are represented on the same voltage{\textendash}current plane. Basic schemes of controllers are suggested to fulfill operation requirements. Curves of power and H2 production rate as function of wind speed are displayed for each mode. Also, conclusions about contribution of wind energy to clean H2 are drawn.

}, url = {http://www.sciencedirect.com/science/article/pii/S0306261910005064}, author = {Garc{\'\i}a-Cl{\'u}a, Jos{\'e} G. and Mantz, Ricardo J. and De Battista, Hern{\'a}n} } @article {22, title = {Sliding mode speed auto-regulation technique for robotic tracking}, journal = {Robotics and Autonomous Systems}, volume = {59}, year = {2011}, pages = {519 - 529}, abstract = {

In advanced industry manufacturing involving robotic operations, the required tasks can be frequently formulated in terms of a path or trajectory tracking. In this paper, an approach based on sliding mode conditioning of a path parametrization is proposed to achieve the greatest tracking speed which is compatible with the robot input constraints (joint speeds). Some distinctive features of the proposal are that: (1) it is completely independent of the robot parameters, and it does not require a priori knowledge of the desired path either, (2) it avoids on-line computations necessary for conventional analytical methodologies, and (3) it can be easily added as a supervisory block to pre-existing path tracking schemes. A sufficient condition (lower bound on desired tracking speed) for the sliding mode regulation to be activated is derived, while a chattering amplitude estimation is obtained in terms of the sampling period and a tunable first-order filter bandwidth. The algorithm is evaluated on the freely accessible 6R robot model PUMA-560, for which a path passing through a wrist singularity is considered to show the effectiveness of the proposal under hard tracking conditions.

}, keywords = {Robotic tracking}, issn = {0921-8890}, doi = {10.1016/j.robot.2011.03.007}, url = {http://www.sciencedirect.com/science/article/pii/S0921889011000595}, author = {Garelli, Fabricio and Gracia, Luis and Sala, Antonio and Albertos, Pedro} } @article {20, title = {Specific growth rate estimation in (fed-)batch bioreactors using second-order sliding observers}, journal = {Journal of Process Control}, volume = {21}, year = {2011}, pages = {1049 - 1055}, abstract = {

This paper addresses the estimation of specific growth rate of microorganisms in bioreactors using sliding observers. In particular, a second-order sliding observer based on biomass concentration measurement is proposed. Differing from other proposals that only guarantee bounded errors, the proposed observer provides a smooth estimate that converges in finite time to the time-varying parameter. Stability is proved using a Lyapunov approach. The observer exhibits also robustness to process uncertainties since no model of the reaction is used for its design. In addition, the off-surface coordinate of the sliding observer is useful to determine the convergence time as well as to identify sensor faults and unexpected behaviors. Because of the structure of the output error injection, chattering phenomena of conventional sliding mode algorithms are substantially reduced. The features of the proposed observer are assessed by numerical and experimental data.

}, keywords = {Bioreactors}, issn = {0959-1524}, doi = {10.1016/j.jprocont.2011.05.008}, url = {http://www.sciencedirect.com/science/article/pii/S0959152411000989}, author = {De Battista, Hern{\'a}n and Pic{\'o}, Jes{\'u}s and Garelli, Fabricio and Vignoni, Alejandro} } @article {115, title = {2-sliding active and reactive power control of a wind energy conversion system}, journal = {Control Theory Applications, IET}, volume = {4}, year = {2010}, month = {November}, pages = {2479-2490}, abstract = {

This study presents the control of a variable-speed wind energy conversion system based on a brushless doubly fed reluctance machine. The control objectives are the tracking of the maximum power conversion point and the regulation of the reactive power injected by the generation system into the grid. The control design is approached using multi-input second-order sliding techniques which are specially appropriate to deal with non-linear system models in the presence of disturbances and model inaccuracies. The controller synthesised through this theoretical framework presents very good robustness features, a finite reaching time and a chattering-free behaviour. The performance of the closed-loop system is assessed through representative computer simulations.

}, keywords = {2-sliding active power control, 2-sliding reactive power control, brushless doubly fed reluctance machine, brushless machines, chattering-free behaviour, closed loop systems, closed-loop system, control design, control system synthesis, controller synthesis, generation system, grid, maximum power conversion point tracking, multiinput second-order sliding technique, Nonlinear control systems, nonlinear system model, Power conversion, power generation control, reactive power control, reactive power regulation, reluctance machines, representative computer simulation, variable structure systems, variable-speed wind energy conversion system, wind power}, issn = {1751-8644}, doi = {10.1049/iet-cta.2009.0437}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5645800}, author = {Valenciaga, Fernando and Evangelista, Carolina A.} } @article {94, title = {Control design for an autonomous wind based hydrogen production system}, journal = {International Journal of Hydrogen Energy}, volume = {35}, year = {2010}, pages = {5799 - 5807}, abstract = {

This paper presents a complete control scheme to efficiently manage the operation of an autonomous wind based hydrogen production system. This system comprises a wind energy generation module based on a multipolar permanent magnet synchronous generator, a lead-acid battery bank as short term energy storage and an alkaline von Hoerner electrolyzer. The control is developed in two hierarchical levels. The higher control level or supervisor control determines the general operation strategy for the whole system according to the wind conditions and the state of charge of the battery bank. On the other hand, the lower control level includes the individual controllers that regulate the respective module operation assuming the set-points determined by the supervisor control. These last controllers are approached using second-order super-twisting sliding mode techniques. The performance of the closed-loop system is assessed through representative computer simulations.

}, keywords = {Hydrogen production}, issn = {0360-3199}, doi = {http://dx.doi.org/10.1016/j.ijhydene.2010.02.096}, url = {http://www.sciencedirect.com/science/article/pii/S0360319910003964}, author = {Valenciaga, Fernando and Evangelista, Carolina A.} } @article {6, title = {Control of a grid-assisted wind-powered hydrogen production system}, journal = {Int J Hydrogen Energy}, volume = {35}, year = {2010}, month = {June}, pages = {5786-5792}, abstract = {

This paper deals with the control of a H2 production system supplied by wind power and assisted by the grid. The system architecture consists of a pitch-controlled wind turbine coupled through a diode rectifier to an alkaline electrolyzer, which in turn is connected to the electric grid through a fully-controlled bidirectional electronic converter. A control strategy for the electronic converter is proposed to regulate the electrolyzer current at its rated value. Thus, H2 production efficiency is optimized despite wind power and temperature variability. Control design is based on sliding mode techniques, which are particularly appropriate to control fast switching devices and exhibit strong robustness properties. Additionally, in high wind speeds, a pitch control loop is activated to limit the wind power capture below admissible values.

}, url = {http://www.sciencedirect.com/science/article/pii/S0360319910003988}, author = {Garc{\'\i}a-Cl{\'u}a, Jos{\'e} G. and De Battista, Hern{\'a}n and Mantz, Ricardo J.} } @conference {212, title = {Low-cost sliding-mode power controller of a stand-alone photovoltaic module}, booktitle = {2010 IEEE International Conference on Industrial Technology}, year = {2010}, month = {March}, abstract = {This work presents a simple and low-cost power electronic system that allows a flexible control of the operating conditions of the photovoltaic module. The system consists of a buck converter with sliding mode control. Control algorithms for maximum power tracking, module voltage and load current regulation are proposed. Moreover, these algorithms can be readily combined to have a complete control of the energy conversion system. The dynamic analysis reveals that there may be regions of instability that are avoided by appropriate switching logics. Operation and main features of the proposed electronic power controller are validated through simulation and experimental results.}, keywords = {Buck converters, Control systems, Current control, electric current control, energy conversion, load current regulation, Logic, maximum power point trackers, maximum power tracking, module voltage control, photovoltaic cells, Photovoltaic systems, Power control, power controller, Power electronics, Sliding mode control, Solar power generation, stand-alone photovoltaic module, variable structure systems, voltage control}, doi = {10.1109/ICIT.2010.5472600}, author = {Inthamoussou, Fernando A. and De Battista, Hern{\'a}n and Cendoya, Marcelo} } @article {24, title = {Multi-loop two-degree-of-freedom {PI} controllers with adaptive set-point weighting}, journal = {Proceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering}, volume = {224}, year = {2010}, pages = {1033-1039}, abstract = {

This note describes a simple technique to adapt the set-point weighting of multivariable two-degree-of-freedom proportional-integral (PI) controllers. This controller structure has been extensively used in single-input-single-output (SISO) systems to design disturbance and set-point responses independently. In multivariable systems, the interaction among the different loops can be minimized by making the set-point weighting zero. However, the cancellation of the reference direct path leads to a degradation of set-point tracking performance. The weighting adaptation proposed here aims to conserve the interaction magnitude level corresponding to zero weighting but improving the response of the direct control loop. Variable structure control-related concepts may be used to analyse the methodology, since a switching law is used in order to generate the weighting factor. {\textcopyright} Authors 2010.

}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-78650137494\&partnerID=40\&md5=760c0f3a8e5e6a30f6f7d2b432636a2a}, author = {Garelli, Fabricio and Mantz, Ricardo J. and De Battista, Hern{\'a}n} } @article {29, title = {Second order sliding power control for a variable speed-constant frequency energy conversion system}, journal = {Energy Conversion and Management}, volume = {51}, year = {2010}, pages = {3000 - 3008}, abstract = {

This paper presents a decoupled active and reactive power control for a variable speed-constant frequency generation system based on a brushless doubly fed reluctance machine. The control design is approached using multi-input second order sliding techniques which are specially appropriate to deal with nonlinear system models in presence of external disturbances and model inaccuracies. The controller synthesized through this theoretical framework presents very good robustness features, a finite reaching time and a chattering-free behavior. The performance of the closed loop system is assessed through representative computer simulations.

}, keywords = {Power control}, issn = {0196-8904}, doi = {10.1016/j.enconman.2010.06.047}, url = {http://www.sciencedirect.com/science/article/pii/S0196890410002591}, author = {Valenciaga, Fernando} } @article {92, title = {A simple robust controller for power maximization of a variable-speed wind turbine}, journal = {International Journal of Energy Research}, volume = {34}, year = {2010}, pages = {924{\textendash}932}, abstract = {

This paper presents a high-order sliding mode control strategy that aims to optimize the power conversion efficiency of a wind energy conversion system within the partial load zone of operation. The main challenges of this control problem are related to the random variations of the wind speed, the nonlinear nature of the whole system, usual model uncertainties and external disturbances. For all these reasons, the robustness, simplicity and low computational burden of the proposed super-twisting algorithm result very attractive in this context. Simulation results that show the achievement of the desired characteristics are provided. Copyright {\^A}{\textcopyright} 2009 John Wiley \& Sons, Ltd.

}, keywords = {efficiency optimization, Robust control, Sliding mode, Wind energy}, issn = {1099-114X}, doi = {10.1002/er.1613}, url = {http://dx.doi.org/10.1002/er.1613}, author = {Evangelista, Carolina A. and Puleston, Pablo F. and Valenciaga, Fernando} } @conference {91, title = {Variable gains super-twisting control for wind energy conversion optimization}, booktitle = {Variable Structure Systems (VSS), 2010 11th International Workshop on}, year = {2010}, month = {June}, abstract = {

An adaptive second order sliding mode control strategy is explored in this work, to maximize the energy extracted from the wind in a wind energy conversion system (WECS). It is required to such strategy to deal with the nonlinear nature of the WECS, the randomness of the wind speed, model uncertainties and external disturbances, and also with the need to reduce mechanical loads. The special features of this adaptive technique together with the robustness, relative simplicity and other desirable inherent characteristics of the super-twisting algorithm make the proposed controller an attractive solution. The suitability of the proposed strategy is proved by extensive computer aided simulations employing a comprehensive model of the system.

}, keywords = {adaptive control, adaptive second order sliding mode control, Computational modeling, computer aided simulation, Computer Simulation, control system synthesis, Gain, Lyapunov based controller design, Lyapunov methods, nonlinear systems, optimisation, Programmable control, Robust control, Sliding mode control, Uncertainty, variable gain super twisting control, variable structure systems, Wind energy, wind energy conversion optimization, wind power, Wind speed}, doi = {10.1109/VSS.2010.5544713}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5544713}, author = {Evangelista, Carolina A. and Puleston, Pablo F. and Valenciaga, Fernando and D{\textquoteright}ávila, A.} } @article {23, title = {Variable structure strategy to avoid amplitude and rate saturation in pitch control of a wind turbine}, journal = {International Journal of Hydrogen Energy}, volume = {35}, year = {2010}, pages = {5869-5875}, abstract = {

This work proposes the application of a recent compensation technique for input constraints avoidance to the pitch control of a wind turbine. The pitch angle actuators commonly present a hard limit on their rate of change together with the natural amplitude saturation, and a dynamics during their unconstrained operation that can be modeled as a first-order linear system. This dynamic behavior of the pitch actuator requires a particular design of the compensation method, which is based on variable structure systems to avoid both amplitude and rate input saturation by means of an auxiliary loop. The developed methodology reduces the pitch actuator activity necessary to regulate the generated power around its nominal value when facing sudden wind gusts. Another interesting feature of the proposal is that it allows the operator to fix conservative bounds for the actuator speed operation in order to increment the structural robustness of the wind turbine and to extend in this way the service life of the energy system. The effectiveness of the proposed strategy is evaluated by simulation results in an autonomous wind energy conversion system for water pumping with a brushless double feed induction generator (BDFIG). {\^A}{\textcopyright} 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-77955288770\&partnerID=40\&md5=99abf237285a7cc32602254926b42d81}, author = {Garelli, Fabricio and Camocardi, Pablo and Mantz, Ricardo J.} } @article {95, title = {Wind turbine efficiency optimization. Comparative study of controllers based on second order sliding modes}, journal = {International Journal of Hydrogen Energy}, volume = {35}, year = {2010}, pages = {5934 - 5939}, abstract = {

This paper studies the applicability of second order sliding mode control strategies to a wind energy conversion system aiming to optimise its power conversion efficiency. Four different controllers are designed and analysed, based on the {\^a}{\texteuro}{\oe}sub-optimal{\^a}{\texteuro}�, {\^a}{\texteuro}{\oe}twisting{\^a}{\texteuro}�, {\^a}{\texteuro}{\oe}super-twisting{\^a}{\texteuro}� and {\^a}{\texteuro}{\oe}with a prescribed law of variation{\^a}{\texteuro}� algorithms, which present finite-time convergence, robustness, chattering and mechanical stress reduction, and are of quite simple online operation and implementation. Representative simulation results are shown, using a complete model of the system under realistic operating conditions, where the performance of the controlled system can be appreciated for each of the controllers and some comparisons can be made.

}, keywords = {Wind energy}, issn = {0360-3199}, doi = {http://dx.doi.org/10.1016/j.ijhydene.2009.12.104}, url = {http://www.sciencedirect.com/science/article/pii/S0360319909020321}, author = {Evangelista, Carolina A. and Puleston, Pablo F. and Valenciaga, Fernando} } @article {97, title = {Chattering reduction in a geometric sliding mode method. A robust low-chattering controller for an autonomous wind system}, journal = {Control and Intelligent Systems}, volume = {37}, year = {2009}, pages = {39-45}, abstract = {

This paper focuses on the design of reduced chattering sliding mode controllers and its application to the optimization of a wind energy system. It develops, in an accessible way, an enhanced control design method suitable for a wide range of engineering applications, namely those that accept a certain degree of discontinuous action in their input and that can be described as non-linear systems affine in the control with a vector of bounds for the uncertainties. The proposed systematic method is based on a geometric approach developed by the authors in a previous work. This new proposal reduces the chattering while maintaining the attractive features of the original method, those are robustness, tuning simplicity and reaching mode control. Taking advantage of these attributes, a robust low-chattering controller for an autonomous wind energy conversion system based on a permanent magnet generator is developed.

}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-69949101463\&partnerID=40\&md5=f0d260771e03dfedadb0184db4eb2625}, author = {Puleston, Pablo F. and Valenciaga, Fernando} } @article {98, title = {A geometric approach for the design of MIMO sliding controllers. Application to a wind-driven doubly fed induction generator}, journal = {International Journal of Robust and Nonlinear Control}, volume = {19}, year = {2009}, pages = {22{\textendash}39}, abstract = {

This paper presents a systematic methodology to design controllers for a general class of nonlinear MIMO systems affine in the control in the presence of bounded uncertainties and disturbances. The design method is developed using a theoretical framework based on the combination of a geometric approach and sliding mode techniques. The resulting robust control law guarantees finite time convergence, whereas chattering reduction is achieved by utilizing the minimum discontinuous action required to ensure disturbance rejection. The proposed methodology is applied to the control of a grid-connected wind energy generation system based on a doubly fed induction generator. The control objectives considered in this paper are maximization of the wind energy conversion and reactive power regulation to minimize machine losses. Copyright {\^A}{\textcopyright} 2008 John Wiley \& Sons, Ltd.

}, keywords = {efficiency optimization, Sliding mode control, Wind energy}, issn = {1099-1239}, doi = {10.1002/rnc.1323}, url = {http://dx.doi.org/10.1002/rnc.1323}, author = {Valenciaga, Fernando and Puleston, Pablo F. and Spurgeon, Sarah} } @article {26, title = {Geometric invariance and reference conditioning ideas for control of overflow metabolism}, journal = {Journal of Process Control}, volume = {19}, year = {2009}, pages = {1617-1626}, abstract = {

In many biotechnological processes, the optimal productivity corresponds to operating at critical substrate concentration. The problem, then, consists in finding the feeding rate compatible with the critical constraint which gives a specific growth rate as close as possible to the desired one, so as to avoid overflow metabolism. This value may be unknown and may change from experiment to experiment and from strain to strain, and even in the same experiment due to changing environmental and/or process conditions. Particularly, in the fed-batch fermentation of the industrial strain Saccharomyces cerevisiae a small amount of ethanol is allowed to be present in the culture, and the control problem is one of regulating the ethanol concentration at a given low reference value. In this paper, an approach based on geometric invariance via sliding mode reference conditioning is proposed to achieve the closest specific growth rate to the desired reference which is compatible with system constraints (e.g. ethanol concentration lower than a given threshold). It is shown how this approach is robust with respect to uncertainties in the process dynamics and with respect to unknown perturbations affecting the critical point. {\textcopyright} 2009 Elsevier Ltd. All rights reserved.

}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-72149130534\&partnerID=40\&md5=3403e3d5004233463a967f09fb375648}, author = {Pic{\'o}, Jes{\'u}s and Garelli, Fabricio and De Battista, Hern{\'a}n and Mantz, Ricardo J.} } @article {136, title = {Simulaci{\'o}n de un algoritmo para controlar el nivel en tolva ante alimentaci{\'o}n discontinua de ca{\~n}a}, journal = {Revista Iberoamericana de Autom{\'a}tica e Inform{\'a}tica Industrial RIAI}, volume = {6}, year = {2009}, pages = {54 - 60}, abstract = {

Los actuales m{\'e}todos de control del transporte y preparaci{\'o}n de la materia prima provocan graves problemas de discontinuidad en la alimentaci{\'o}n al tren de molinos de ca{\~n}a en la industria azucarera en Cuba. La introducci{\'o}n masiva de la tecnolog{\'\i}a de convertidores de frecuencia para el control de velocidad de motores asincr{\'o}nicos permite proponer la utilizaci{\'o}n de la velocidad de las esteras como variable manipulada para el control del nivel de la tolva. Este trabajo presenta una variante de control por velocidad considerando la altura del colch{\'o}n de ca{\~n}a en la estera elevadora como una perturbaci{\'o}n multiplicativa a la entrada de la planta. Se propone un algoritmo de adaptaci{\'o}n de set-point por modo deslizante para limitar los transitorios en el nivel de ca{\~n}a en tolva provocados por las fluctuaciones en la alimentaci{\'o}n de ca{\~n}a. El m{\'e}todo propuesto requiere realimentar {\'u}nicamente variables accesibles y es robusto ante cambios en la densidad de ca{\~n}a y/o ruido de medici{\'o}n. Su implementaci{\'o}n es extremadamente sencilla para lazos de control por velocidad tipo PID.

}, keywords = {set-point adaptivo}, issn = {1697-7912}, doi = {http://dx.doi.org/10.1016/S1697-7912(09)70264-X}, url = {http://www.sciencedirect.com/science/article/pii/S169779120970264X}, author = {Garelli, Fabricio and Ram{\'\i}rez, M. M. and Dom{\'\i}nguez, C. A. and Angulo, A. M.} } @article {25, title = {Smooth sliding-mode observers for specific growth rate and substrate from biomass measurement}, journal = {Journal of Process Control}, volume = {19}, year = {2009}, pages = {1314-1323}, abstract = {

This paper addresses the estimation of specific growth rate and substrate concentration from biomass measurements in fermentation processes. Specifically, sliding-mode observers are proposed, for which finite-time global convergence is demonstrated using Lyapunov stability theory and concepts of variable structure systems. Two observers are developed for specific growth rate estimation, one producing a discontinuous estimation which is used afterwards for substrate estimation, and the other one - based on high-gain observers - that generates a smooth estimation with first-order dynamics and finite-time bounded convergence error. In the case of substrate estimation, an observer that increases the convergence rate to a vicinity of the real substrate concentration while achieving asymptotic convergence despite kinetic model uncertainties in properly excited processes is designed. This observer also exhibits first-order dynamics. {\textcopyright} 2009 Elsevier Ltd. All rights reserved.

}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-70249132897\&partnerID=40\&md5=c62475aecf0ddcdbe3fc78e750190074}, author = {Pic{\'o}, Jes{\'u}s and De Battista, Hern{\'a}n and Garelli, Fabricio} } @conference {100, title = {Active and reactive power control of a brushless doubly fed reluctance machine using high order sliding modes}, booktitle = {Electrical Machines, 2008. ICEM 2008. 18th International Conference on}, year = {2008}, month = {Sept}, abstract = {

This article develops a decoupled active and reactive power control for a variable-speed constant-frequency (VSCF) power generation system based on a brushless doubly fed reluctance machine. This machine is a forthcoming low cost candidate for applications with limited variable speed requirements such as pumping and wind generation. Basically, it allows the use of a partially rated power electronic converter and, at the same time, offers a reliable and maintenance-free operation because of its brushless feature. The control design is approached through second order sliding mode techniques. This theoretical framework permits to deal with systems described by perturbed nonlinear dynamic models, obtaining simple controllers with a finite time reaching phase and a chattering free behavior. The controller performance is assessed through exhaustive simulations.

}, keywords = {active power control, brushless doubly fed reluctance machine, brushless machines, chattering free behavior, Converters, Costs, high order sliding modes, machine control, perturbed nonlinear dynamic models, Power conversion, power electronic converter, Power electronics, Pumps, reactive power control, reluctance machines, Sliding mode control, variable structure systems, variable-speed constant-frequency power generation system, Wind energy generation, Wind power generation}, doi = {10.1109/ICELMACH.2008.4799959}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=4799959}, author = {Valenciaga, Fernando} } @article {54, title = {Collective Sliding-Mode Technique for Multivariable Bumpless Transfer}, journal = {Industrial \& Engineering Chemistry Research}, volume = {47}, year = {2008}, pages = {2721-2727}, abstract = {

This paper proposes a strategy for the reduction of the undesired effects caused by manual-automatic or controller switching in multivariable process control. The proposal takes advantage of dynamic sliding mode properties to avoid inconsistency between the off-line controller outputs and the plant inputs. As a consequence, jumps at the plant inputs are prevented (which is known as bumpless transfer) and undesired transients on controlled variables are significantly reduced. Some advantages of the proposed algorithm are that (1) its implementation is extremely simple, (2) it presents distinctive robustness properties, which are characteristic of sliding regimes, and (3) it does not need the model of the plant.

}, doi = {10.1021/ie070870q}, url = {http://dx.doi.org/10.1021/ie070870q}, author = {Garelli, Fabricio and Mantz, Ricardo J. and De Battista, Hern{\'a}n} } @conference {101, title = {Experimental results on smooth path tracking with application to pipe surveying on inexpensive AUV}, booktitle = {Intelligent Robots and Systems, 2008. IROS 2008. IEEE/RSJ International Conference on}, year = {2008}, month = {Sept}, abstract = {

This paper details the development aspects of a low cost AUV autonomous, designed for autonomous pipline inspections, describing: hardware, software and control aspects. The article details three of the mains stages of the project, that have been already achieved: (a) the simulation results of Lyapunov based path planning of torpedo shaped AUV on pipe searching; (b) the construction details of dual torpedo AUV for pipeline inspection and (c) the experimental results when using the prototype in path following using the line of sight (LOS) algorithm.

}, keywords = {autonomous pipline inspections, Equations, industrial robots, inspection, line of sight algorithm, Lyapunov based path planning, Lyapunov methods, Mathematical model, mobile robots, Navigation, path following, Path planning, pipe searching, pipe surveying, Pipelines, pipes, remotely operated vehicles, smooth path tracking, torpedo shaped AUV, Trajectory, Vehicles}, doi = {10.1109/IROS.2008.4650966}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=4650966}, author = {Calvo, Oscar and Rozenfeld, Alejandro and Souza, A. and Valenciaga, Fernando and Puleston, Pablo F. and Acosta, Gerardo} } @article {99, title = {High-Order Sliding Control for a Wind Energy Conversion System Based on a Permanent Magnet Synchronous Generator}, journal = {Energy Conversion, IEEE Transactions on}, volume = {23}, year = {2008}, month = {Sept}, pages = {860-867}, abstract = {

This paper presents the output power control of a wind energy conversion system (WECS) based on a permanent magnet synchronous generator (PMSG). It is assumed that the considered wind module integrates a stand-alone hybrid generation system, jointly with a battery bank, a variable ac load, and other generation subsystems. The operation strategy of the hybrid system determines two possible operation modes for the WECS, depending on the power requirements of the load and the wind availability. The paper deals with the design of a combined high-order sliding mode (HOSM) controller for the power control of the WECS on both operational modes. The main features of the obtained controller are its chattering-free behavior, its finite-time reaching phase, its simplicity, and its robustness with respect to external disturbances and unmodeled dynamics. The performance of the closed-loop system is assessed through representative computer simulations.

}, keywords = {chattering-free behavior, closed loop systems, closed-loop system, external disturbances, finite-time reaching phase, High-order sliding mode (HOSM), high-order sliding mode controller, nonlinear systems, permanent magnet generators, permanent magnet synchronous generator, PMSG, Power control, power generation control, stand-alone hybrid generation system, synchronous generators, variable structure systems, WECS, Wind energy, wind energy conversion system, wind power plants}, issn = {0885-8969}, doi = {10.1109/TEC.2008.922013}, author = {Valenciaga, Fernando and Puleston, Pablo F.} } @article {27, title = {Hybrid control of a photovoltaic-hydrogen energy system}, journal = {Int J Hydrogen Energy}, volume = {33}, year = {2008}, pages = {3455 - 3459}, abstract = {

This paper concerns the control of an autonomous hydrogen production system basically consisting in a solar panel array supplying an alkaline electrolyzer. Following the current tendency of eliminating component duplication, these devices are not connected{\textemdash}with dedicated power electronics{\textemdash}to a common DC bus, but directly through a single DC{\textendash}DC converter. This converter is aimed at adjusting the output voltages of the solar array and electrolyzer in order to maximize hydrogen production. To this end, a controller is proposed that meets the maximum power capture objective for the solar array and the power constraints of the electrolyzer. The controller is designed using concepts of hybrid control theory, which is very powerful to cope with the nonlinear and hybrid dynamics inherent to the system behavior. This hybrid approach provides simple design tools and allows a straightforward analysis of global stability properties.

}, url = {http://www.sciencedirect.com/science/article/pii/S0360319907008051}, author = {Garc{\'\i}a-Cl{\'u}a, Jos{\'e} G. and Mantz, Ricardo J. and De Battista, Hern{\'a}n} } @article {53, title = {Hydrogen production from idle generation capacity of wind turbines}, journal = {International Journal of Hydrogen Energy}, volume = {33}, year = {2008}, pages = {4291 - 4300}, abstract = {

This paper is concerned with the hydrogen production from wind energy. It is motivated by the new regulations for wind farms that compel them to operate normally with idle generation capacity. The idea is to use the excess wind power to produce hydrogen. The operation of a proposed system configuration, which essentially consists in incorporating an electrolyzer between the electronic converters of a conventional wind turbine, is analyzed. In particular, the control requirements to simultaneously achieve the grid and electrolyzer specifications are investigated. In this context, a control strategy for the different operating modes of the system is developed.

}, keywords = {Hydrogen production}, issn = {0360-3199}, doi = {http://dx.doi.org/10.1016/j.ijhydene.2008.05.088}, url = {http://www.sciencedirect.com/science/article/pii/S0360319908006800}, author = {Mantz, Ricardo J. and De Battista, Hern{\'a}n} } @article {52, title = {Optimal gain-scheduled control of fixed-speed active stall wind turbines}, journal = {Renewable Power Generation, IET}, volume = {2}, year = {2008}, month = {December}, pages = {228-238}, abstract = {

For a smooth integration of large wind farms into the utility grids, the individual wind turbines must be able to achieve various power control objectives. In this context, the authors focus their attention on the control of fixed-speed active stall wind turbines. This sort of turbine includes a pitch servomechanism to induce stall on the blades, thereby having control on the output power. The authors develop a methodology to design optimal gain-scheduled pitch controllers valid for the whole operating region of the wind turbine. The proposed solution uses concepts of linear parameter-varying system theory. In addition to providing a formal framework for the control design, this theory guarantees stability and performance. Further, because of the similarities with Hinf control, the tools developed for the controller design are very familiar to the control community. The main features of the proposed controller are assessed by means of numerical simulations obtained for realistic wind speed profiles and power production demands.

}, keywords = {fixed-speed active stall wind turbines, Hinf control, Hinfin control, linear parameter-varying system theory, linear systems, optimal gain-scheduled control, pitch servomechanism, power generation control, power production demands, wind farms, wind speed profiles, wind turbines}, issn = {1752-1416}, doi = {10.1049/iet-rpg:20070106}, url = {http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4610980\&tag=1}, author = {Bianchi, Fernando D. and De Battista, Hern{\'a}n and Mantz, Ricardo J.} } @mastersthesis {153, title = {Constrained Control using Variable Structure Systems}, volume = {PhD}, year = {2007}, school = {Universidad Nacional de La Plata}, type = {PhD}, address = {La Plata, Buenos Aires, Argentina}, abstract = {En este trabajo de tesis se aborda el control de sistemas multivariables con restricciones. Uno de los principales objetivos es el desarrollo de nuevas estrategias de control que permitan reducir las interacciones cruzadas de los sistemas de m{\'u}ltiples entradas y m{\'u}ltiples salidas; es decir, mejorar su grado de desacoplamiento. Este problema se considera para diferentes limitaciones en la planta (restricciones a la entrada, restricciones a la salida, ceros de fase no-m{\'\i}nima) y distintas estructuras de control (controladores centralizados y descentralizados). Las estrategias propuestas combinan conceptos de la teor{\'\i}a de control por estructura variable y el acondicionamiento de la se{\~n}al de referencia.}, url = {http://sedici.unlp.edu.ar/handle/10915/1363}, author = {Garelli, Fabricio} } @article {55, title = {Sliding mode compensation to preserve dynamic decoupling of stable systems}, journal = {Chemical Engineering Science}, volume = {62}, year = {2007}, pages = {4705 - 4716}, abstract = {

Dynamic decoupling of linear multiple-input and multiple-output systems involves both static and transient decoupling between inputs and outputs of the system. Different control techniques exist in order to achieve this specification when ideal actuators are considered. However, input saturation changes the direction of the plant input with respect to the controller output and, as a consequence, decoupling is lost. This paper presents a method that allows, by means of a sliding mode (SM) auxiliary loop, maintaining dynamic decoupling even in the presence of actuator saturation. Since the SM compensation is confined to the low-power side of the control system, the discontinuous signal can be implemented with fast switching devices or, in the case of digital controllers, within a microprocessor algorithm. Furthermore, due to the robustness properties of SM, the compensation loop dynamics may be assigned independently of the main control loop.

}, keywords = {Process control}, issn = {0009-2509}, doi = {http://dx.doi.org/10.1016/j.ces.2007.05.020}, url = {http://www.sciencedirect.com/science/article/pii/S0009250907004150}, author = {Garelli, Fabricio and Mantz, Ricardo J. and De Battista, Hern{\'a}n} } @article {105, title = {A STATCOM based variable structure control for power system oscillations damping}, journal = {International Journal of Electrical Power \& Energy Systems}, volume = {29}, year = {2007}, pages = {241 - 250}, abstract = {

The problem of underdamped power oscillations in transmission systems is addressed in this paper. Different algorithms for \{STATCOM\} voltage control are designed to inject extra friction in order to eliminate such undesirable oscillating behaviour. In particular, a variable structure control law, combining continuous and discontinuous actions exhibits an especially good performance. The efficiency of the proposed control laws are tested and analysed through computer simulation.

}, keywords = {\{FACTS\}}, issn = {0142-0615}, doi = {http://dx.doi.org/10.1016/j.ijepes.2006.07.003}, url = {http://www.sciencedirect.com/science/article/pii/S0142061506001487}, author = {Puleston, Pablo F. and Gonzalez, Sergio and Valenciaga, Fernando} } @conference {102, title = {Trajectory tracking of the cormoran AUV based on a PI-MIMO approach}, booktitle = {OCEANS 2007 - Europe}, year = {2007}, abstract = {

This paper describes the control strategy developed for the Cormoran, a low cost ocean observing platform, hybrid between AUVs and ASVs, This robot moves slightly underneath the sea surface following a previously planned route and regularly dives Lo make vertical profiles of the water column. Obtained data is transmitted in real time to the laboratory and assimilated into a numerical coastal model. The control structure proposed in this article comprises a Navigation Block and a MIMO Control Block. The former is based on a following Lyapunov-based algorithm and computes on-line the reference signals required by the latter to reach and robustly track the desired trajectory. The MIMO Control Block architecture is based on a PI-MIMO control strategy that commands the rudder and the propeller. Computer simulations utilizing a dynamic model of the Cormoran and realistic disturbances are presented. {\^A}{\textcopyright} 2007 IEEE.

}, doi = {10.1109/ICELMACH.2008.4799959}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-36349021879\&partnerID=40\&md5=717cb63ba05095647e2388f98657956a}, author = {Valenciaga, Fernando and Puleston, Pablo F. and Calvo, Oscar and Acosta, Gerardo} } @article {103, title = {Variable structure control of a wind energy conversion system based on a brushless doubly fed reluctance generator}, journal = {IEEE Transactions on Energy Conversion}, volume = {22}, year = {2007}, pages = {499-506}, abstract = {

This paper introduces a variable structure robust controller for wind energy conversion systems based on brushless doubly fed reluctance machine. Two simultaneous control goals are tackled: maximization of the wind energy conversion efficiency and minimization of the machine copper losses. The proposed multiple-input multiple-output (MIMO) robust controller is systematically synthesized following a general design method for MIMO nonlinear affine systems. The design is approached through a theoretical framework based on the combination of variable structure techniques and the Lyapunov{\textquoteright}s theory. Robustness to bounded disturbances and chattering minimization is attained. {\^A}{\textcopyright} 2007 IEEE.

}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-34249782852\&partnerID=40\&md5=fc6c1e4e691c76eb77d28eed532c8270}, author = {Valenciaga, Fernando and Puleston, Pablo F.} } @conference {104, title = {A Geometric Approach for the Design of MIMO Sliding Controllers. Application to a Wind Driven Double Output Induction Generator}, booktitle = {Variable Structure Systems, 2006. VSS{\textquoteright}06. International Workshop on}, year = {2006}, month = {June}, abstract = {

This paper presents a systematic methodology to design controllers for a general class of nonlinear MIMO systems affine in the control in the presence of bounded uncertainties and disturbances. The proposed design method is developed through a theoretical framework based on the combination of a geometric approach and sliding mode techniques. The resulting robust control law guarantees finite time convergence, while chattering reduction is attained by utilising the minimum discontinuous action required to ensure disturbance rejection. The proposed methodology is applied to the control of a grid connected wind energy generation system based on a double output induction generator

}, keywords = {asynchronous generators, chattering reduction, control system synthesis, Control systems, controller design, Convergence, Design methodology, finite time convergence, geometric approach, grid connected wind energy generation system, Induction generators, MIMO, MIMO sliding mode controllers, MIMO systems, Nonlinear control systems, nonlinear MIMO systems, power generation control, Robust control, Sliding mode control, Uncertainty, variable structure systems, wind driven double output induction generator, Wind energy generation, wind power}, doi = {10.1109/VSS.2006.1644503}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1644503}, author = {Valenciaga, Fernando and Puleston, Pablo F. and Spurgeon, Sarah} } @article {28, title = {Globally stabilizing control of fed-batch processes with Haldane kinetics using growth rate estimation feedback}, journal = {Journal of Process Control}, volume = {16}, year = {2006}, pages = {865 - 875}, abstract = {

The regulation of the biomass specific growth rate is an important goal in many biotechnological applications. To achieve this goal in fed-batch processes, several control strategies have been developed employing a closed loop version of the exponential feeding law, an estimation of the controlled variable and some error feedback term. In the case of non-monotonic kinetics, the specified growth rate can be achieved at two different substrate concentration values. Because of the inherent unstable properties of the system in the decreasing portion of the kinetics function, stabilization becomes a crucial problem in this high-substrate operating region. In this context, the dynamic behavior of fed-batch processes with Haldane kinetics is further investigated. In particular, some conditions for global stability and performance improvement are derived. Then, a stabilizing control law based on a partial state feedback with gain dependent on the output error feedback and gain saturation is proposed. Although particular emphasis is put on the critical case of high-substrate operation, low-substrate regulation is also treated.

}, keywords = {Nonlinear control}, issn = {0959-1524}, doi = {10.1016/j.jprocont.2006.02.001}, url = {http://www.sciencedirect.com/science/article/pii/S0959152406000229}, author = {De Battista, Hern{\'a}n and Pic{\'o}, Jes{\'u}s and Pic{\'o}-Marco, Enric} } @article {57, title = {Limiting interactions in decentralized control of MIMO systems}, journal = {Journal of Process Control}, volume = {16}, year = {2006}, pages = {473 - 483}, abstract = {

Despite the closed-loop performance advantages of centralized multivariable controllers, the great majority of industrial process control applications is still based on decentralized controllers. Because of their single loop structure, decentralized controllers cannot suppress the interactions of the plant, which are only taken into account in the controller tuning phase. Therefore, it would be useful in many cases to delimit in some way the undesirable effects of the coupling between inputs and outputs of the closed loop system. A control algorithm to achieve this goal is developed in the paper. The proposal is applicable even to processes with non-minimum phase transmission zeros (provided their off-diagonal transfer functions have their zeros in the left-half-plane). Based on sliding mode attributes, the proposed scheme can be easily added to a previously designed decentralized control system.

}, keywords = {Decentralized control}, issn = {0959-1524}, doi = {http://dx.doi.org/10.1016/j.jprocont.2005.09.001}, url = {http://www.sciencedirect.com/science/article/pii/S0959152405000995}, author = {Garelli, Fabricio and Mantz, Ricardo J. and De Battista, Hern{\'a}n} } @article {56, title = {Partial decoupling of non-minimum phase processes with bounds on the remaining coupling}, journal = {Chemical Engineering Science}, volume = {61}, year = {2006}, pages = {7706 - 7716}, abstract = {

Partial (triangular) decoupling of MIMO systems has been considered in the literature as a way of relaxing the design limitations introduced by diagonal decoupling in non-minimum phase processes. The former strategy allows decoupling a variable of interest without affecting it with non-minimum phase dynamics. However, when right-half plane (RHP) zeros are mainly aligned with this variable, pushing the effect of the RHP zeros to other outputs comes at the cost of great interactions in those variables. This article presents a method to delimit these interactions without degrading significantly the decoupled variable response. To this end, the algorithm shapes the reference signal by means of an auxiliary sliding mode loop.

}, keywords = {Process control}, issn = {0009-2509}, doi = {http://dx.doi.org/10.1016/j.ces.2006.09.008}, url = {http://www.sciencedirect.com/science/article/pii/S000925090600580X}, author = {Garelli, Fabricio and Mantz, Ricardo J. and De Battista, Hern{\'a}n} } @article {58, title = {Power conditioning for a wind-hydrogen energy system}, journal = {Journal of Power Sources}, volume = {155}, year = {2006}, pages = {478 - 486}, abstract = {

In addition to the efforts to reduce the costs of renewable energy technologies and electrolyzers, the development of suitable controllers are needed for cost-competitive electricity production by renewable-hydrogen power plants. In this paper, a novel control is proposed for a wind-electrolysis system, which match the wind power output to the electrolyzer power requirements, thus gaining in system performance. It basically consists in continuously shaping the power reference of a conventional maximum power point tracking algorithm. Thus, high aerodynamic power conversion efficiency is achieved fulfilling at the same time the electrolyzer specifications. This control strategy is developed using concepts of the reference conditioning technique and of the sliding mode control theory. The proposed control algorithm is extremely simple, easy to implement and robust to parameter uncertainties.

}, keywords = {Electrolysis}, issn = {0378-7753}, doi = {http://dx.doi.org/10.1016/j.jpowsour.2005.05.005}, url = {http://www.sciencedirect.com/science/article/pii/S0378775305006890}, author = {De Battista, Hern{\'a}n and Mantz, Ricardo J. and Garelli, Fabricio} } @book {83, title = {Wind Turbine Control Systems: Principles, Modelling and Gain-scheduling Design}, series = {Advances in Industrial Control}, year = {2006}, publisher = {Springer}, organization = {Springer}, abstract = {

Modern wind turbines generally operate at variable speed in order to maximise the conversion efficiency below rated power and to reduce loading on the drive-train. In addition, pitch control of the blades is usually employed to limit the energy captured during operation above rated wind speed. The higher complexity of variable-speed variable-pitch turbines is offset by the benefits of control flexibility, namely, higher conversion efficiency, better power quality, longer useful life; because of the immediate impact of control on the cost of wind energy, reliable high-performance controllers are essential in making wind technology competitive. In Wind Turbine Control Systems the application of linearparameter varying (LPV) gain scheduling techniques to the control of wind energy conversion systems is emphasised. This recent reformulation of the classical gain scheduling problem allows a straightforward design procedure and simple controller implementation. The monograph provides a thorough coverage of wind turbine control, including:

{\textbullet} an overview of the principles of wind energy conversion;

{\textbullet} the control-oriented modelling of wind turbines;

{\textbullet} an in-depth analysis of the most common control strategies;

{\textbullet} the design of LPV gain-scheduled controllers for both fixed- and variable-pitch, variable-speed wind turbines.

Wind Turbine Control Systems is primarily intended for researchers and students with a control background wishing to expand their knowledge of wind energy systems. The book will be useful to scientists in the field of control theory looking to apply their innovative control ideas to this appealing control problem and will also interest practising engineers dealing with wind technology who will benefit from the comprehensive coverage of the theoretic control topics, the simplicity of the models and the use of commonly available control algorithms.

}, url = {http://www.springer.com/engineering/control/book/978-1-84628-492-2}, author = {Bianchi, Fernando D. and De Battista, Hern{\'a}n and Mantz, Ricardo J.} } @inbook {96, title = {Control of fed-batch bioreactors}, booktitle = {Nonlinear and Adaptive Control: Tools and Algorithms for the User}, year = {2005}, pages = {207-237}, publisher = {Imperial College Press}, organization = {Imperial College Press}, chapter = {1}, abstract = {

This chapter addresses the control of microbial speci c growth rate in fedbatch bioreactors. Practical constraints concerning the available signals and information on the process are dealt with. Then, for a large class of bioreactions, namely pure cultures with one limiting substrate and oxygen in excess, the control problem is regarded as a problem of coordinating control involving the invariance and attractivity of nontrivial sets in state space. Both monotonous and non-monotonous kinetic functions are dealt with. The dissolved oxygen signal can give valuable information about the cell culture, when the oxygen supply is in balance with the consumption. This is utilized for a probing feeding strategy, treated in chapter 1, part II.

}, url = {http://www.worldscientific.com/worldscibooks/10.1142/p420}, author = {Pic{\'o}, Jes{\'u}s and Pic{\'o}-Marco, Enric and Navarro, Jos{\'e} L. and De Battista, Hern{\'a}n}, editor = {Astolfi, Alessandro} } @article {60, title = {On Feedback Stabilization of Fed-Batch Bioreactors: Non-Monotonic Growth Kinetics}, journal = {Biotechnology Progress}, volume = {21}, year = {2005}, pages = {651{\textendash}652}, issn = {1520-6033}, doi = {10.1021/bp050039d}, url = {http://dx.doi.org/10.1021/bp050039d}, author = {De Battista, Hern{\'a}n and Pic{\'o}-Marco, Enric and Pic{\'o}, Jes{\'u}s} } @article {79, title = {Gain scheduling control of variable-speed wind energy conversion systems using quasi-LPV models}, journal = {Control Engineering Practice}, volume = {13}, year = {2005}, pages = {247 - 255}, abstract = {

The paper deals with the control of variable-speed wind energy conversion systems (WECS) in the context of linear parameter varying (LPV) systems, a recent formulation of the classic gain scheduling technique. The LPV approach is specially useful in variable-speed WECS control, which is characterized by nonlinear dynamic behavior and opposite objectives. In particular, the following objectives are considered: conversion efficiency maximization, safe operation, resonant modes damping, and robust stability. The proposed LPV controller is compared with a fixed controller that also takes into account the nonlinear behavior of the wind turbine.

}, keywords = {linear parameter varying systems}, issn = {0967-0661}, doi = {http://dx.doi.org/10.1016/j.conengprac.2004.03.006}, url = {http://www.sciencedirect.com/science/article/pii/S0967066104000541}, author = {Bianchi, Fernando D. and Mantz, Ricardo J. and Christiansen, Carlos F.} } @article {61, title = {Sliding mode scheme for adaptive specific growth rate control in biotechnological fed-batch processes}, journal = {International Journal of Control}, volume = {78}, year = {2005}, pages = {128-141}, abstract = {

This paper addresses the control of biomass growth rate in fed-batch bioreactors. The main difficulty when designing controllers for these processes is the lack of accurate on-line knowledge of the controlled variable as well as the strong parameter and model uncertainties. A completely novel approach to the control design is introduced in this paper which allows us to overcome these problems. In fact, the proposed controller, which is applicable to a large class of fermentation processes, requires minimal knowledge of the process parameters and only uses on-line measurement of volume and biomass concentration. First, a reference model is proposed and a goal manifold in the state space is derived where the control objective is satisfied. A partial state feedback law is then proved to be an invariant control for the goal manifold. Then, the feedback gain is dynamically adjusted via a discontinuous action that enforces a sliding regime such that all state trajectories are steered towards the goal manifold. This sliding mode controller presents very attractive robustness properties. The performance of the controller is evaluated through numerical analysis and experimental results.

}, doi = {10.1080/002071705000073772}, url = {http://www.tandfonline.com/doi/full/10.1080/002071705000073772$\#$.VDVL0RaAqrA}, author = {Pic{\'o}-Marco, Enric and Pic{\'o}, Jes{\'u}s and De Battista, Hern{\'a}n} } @article {106, title = {Supervisor control for a stand-alone hybrid generation system using wind and photovoltaic energy}, journal = {IEEE Transactions on Energy Conversion}, volume = {20}, year = {2005}, pages = {398-405}, abstract = {

A comprehensive supervisor control for a hybrid system that comprises wind and photovoltaic generation subsystems, a battery bank, and an ac load is developed in this paper. The objectives of the supervisor control are, primarily, to satisfy the load power demand and, second, to maintain the state of charge of the battery bank to prevent blackout and to extend the life of the batteries. For these purposes, the supervisor controller determines online the operation mode of both generation subsystems, switching from power regulation to maximum power conversion. Decision criteria for the supervisor based on measurable system variables are presented. Finally, the performance of the supervisor controller is extensively assessed through computer simulation using a comprehensive nonlinear model of the plant. {\^A}{\textcopyright} 2005 IEEE.

}, doi = {10.1109/TEC.2005.845524}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-20544440845\&partnerID=40\&md5=051b8c7b1dccc83dfc933b189b246bb6}, author = {Valenciaga, Fernando and Puleston, Pablo F.} } @article {59, title = {VSS global performance improvement based on AW concepts}, journal = {Automatica}, volume = {41}, year = {2005}, pages = {1099 - 1103}, abstract = {

The influence of the reaching mode on the global performance of variable structure systems (VSS) undergoing sliding regimes is stressed. A comparative analysis between the behaviour during this reaching mode of operation and the problem of windup is realized. Based on the similarities between both control problems, some tools of the control theory of constrained linear systems are exploited to improve the reaching mode of VSS.

}, keywords = {Variable structure control}, issn = {0005-1098}, doi = {http://dx.doi.org/10.1016/j.automatica.2005.01.007}, url = {http://www.sciencedirect.com/science/article/pii/S0005109805000464}, author = {Mantz, Ricardo J. and De Battista, Hern{\'a}n and Bianchi, Fernando D.} } @article {65, title = {Comments on "variable-structure PID control to prevent integrator windup"}, journal = {Industrial Electronics, IEEE Transactions on}, volume = {51}, year = {2004}, month = {June}, pages = {736-738}, abstract = {

In the paper by Hodel and Hall, the authors introduce a variable-structure proportional-integral-derivative controller with antiwindup features and compare it with other simple antiwindup methods. It is pointed out here that the conclusions reached from the comparative example are incorrect as the performance of the controllers is not appropriately compared.

}, keywords = {Antiwindup, antiwindup features, Control nonlinearities, Control systems, controllers, Degradation, Furnaces, integrator windup protection, Internet, linear systems, Nonlinear control systems, performance limitations, PID control, Proportional control, proportional-integral-derivative controller, three-term control, variable structure systems, variable-structure systems, Windup}, issn = {0278-0046}, doi = {10.1109/TIE.2004.825205}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1302353}, author = {Mantz, Ricardo J. and De Battista, Hern{\'a}n} } @article {80, title = {Control of variable-speed wind turbines by LPV gain scheduling}, journal = {Wind Energy}, volume = {7}, year = {2004}, pages = {1{\textendash}8}, abstract = {

This article considers gain-scheduling control of variable-speed wind energy conversion systems (WECS) in the context of linear parameter-varying (LPV) systems. The typical problems of the classic gain-scheduling techniques, such as stability guarantees, undesirable transient responses in the controller commutations and arduous design procedures, can be avoided with this new formulation. A model of a variable-speed WECS expressed in LPV form and an optimal LPV gain-scheduling control strategy are presented.

}, keywords = {gain scheduling, linear parameter-varying systems, wind energy conversion systems, wind turbines}, issn = {1099-1824}, doi = {10.1002/we.103}, url = {http://dx.doi.org/10.1002/we.103}, author = {Bianchi, Fernando D. and Mantz, Ricardo J. and Christiansen, Carlos F.} } @article {63, title = {Dynamical variable structure controller for power regulation of wind energy conversion systems}, journal = {Energy Conversion, IEEE Transactions on}, volume = {19}, year = {2004}, month = {Dec}, pages = {756-763}, abstract = {

The paper addresses the problem of output power regulation of fixed-pitch variable-speed wind energy conversion systems. Operation is constrained by practical reasons to the low-speed side of the turbine power-speed curve. Unfortunately, this region is characterized by a nonminimum phase dynamics which is an obstacle to perform the regulation task. A dynamical variable structure controller is developed that accomplishes the control objective despite this limitation. The proposed control strategy presents attractive features such as robustness to parametric uncertainties of the turbine and generator as well as to electric grid disturbances.

}, keywords = {65, Aerodynamics, Control systems, dynamical variable structure controller, electric grid disturbance, Electric variables control, Induction generators, Mesh generation, nonminimum phase dynamic, parametric uncertainty, Power control, Power generation, power generation control, power regulation, power supply quality, power system dynamic stability, power system interconnection, speed curve, turbine power, variable structure systems, Wind energy, wind energy conversion system, Wind energy generation, wind power, Wind speed, wind turbines}, issn = {0885-8969}, doi = {10.1109/TEC.2004.827705}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1359955}, author = {De Battista, Hern{\'a}n and Mantz, Ricardo J.} } @article {81, title = {Power regulation in pitch-controlled variable-speed WECS above rated wind speed}, journal = {Renewable Energy}, volume = {29}, year = {2004}, pages = {1911 - 1922}, abstract = {

In medium to large scale wind energy conversion systems (WECS), the control of the pitch angle of the blades is an usual method for power regulation above rated wind speed. However, limitations of the pitch actuator have a marked influence on the regulation performance. In variable-speed mode, the control of the generator torque is able to reduce the effects of the pitch actuator limitations. Nevertheless, in this case the system is multiple-input multiple-output (MIMO) and then the control design results more complex. In this situation advance control techniques, such as optimal control, are an interesting option for a systematic controller design. This work analyzes variable-pitch power regulation above rated wind speed in the context of optimal control. The analysis is approached from a new point of view in order to establish a clear connection between the choice of the optimization criteria and the compromise between power regulation and pitch actuator limitations.

}, keywords = {wind energy conversion systems}, issn = {0960-1481}, doi = {http://dx.doi.org/10.1016/j.renene.2004.02.009}, url = {http://www.sciencedirect.com/science/article/pii/S0960148104000886}, author = {Bianchi, Fernando D. and Mantz, Ricardo J. and Christiansen, Carlos F.} } @article {62, title = {Sliding Mode Conditioning for Constrained Processes}, journal = {Industrial \& Engineering Chemistry Research}, volume = {43}, year = {2004}, pages = {8251-8256}, abstract = {

A reference conditioning algorithm based on variable structure systems theory is developed to cope with actuator saturation. This sliding mode conditioning presents some distinctive features. In fact, the proposed compensation shapes a realizable reference, thus completely avoiding saturation. Then, the closed loop never leaves its prescribed linear behavior. Furthermore, as a consequence of this property as well as of the robustness features of sliding mode control, the conditioning circuit dynamics can be designed independently of the main loop dynamics. Although the paper mainly focuses on antiwindup compensation, the proposed conditioning algorithm can be exploited to address other problems of constrained processes control.

}, doi = {10.1021/ie049494p}, url = {http://dx.doi.org/10.1021/ie049494p}, author = {Mantz, Ricardo J. and De Battista, Hern{\'a}n and Bianchi, Fernando D.} } @article {64, title = {On the stability of DC-to-DC converters in photovoltaic systems undergoing sliding motions}, journal = {International Journal of Systems Science}, volume = {35}, year = {2004}, pages = {637-647}, abstract = {

This paper deals with the dynamic behaviour of different DC-to-DC switching electronic converters in photovoltaic applications. In particular, the ability of the DC-to-DC converters to accomplish regulation of certain circuit variables, which are related to the control objectives, is examined. This task is addressed from a variable structure system approach. With this aim, the feasibility of establishing stable sliding regimes on different state co-ordinate surfaces is investigated. Differences in the dynamic behaviour of the DC-to-DC switching converters between photovoltaic and conventional power-supply applications are stressed.

}, doi = {10.1080/00207720412331313632}, url = {http://dx.doi.org/10.1080/00207720412331313632}, author = {Bianchi, Fernando D. and De Battista, Hern{\'a}n and Mantz, Ricardo J.} } @article {107, title = {Variable structure system control design method based on a differential geometric approach: Application to a wind energy conversion subsystem}, journal = {IEE Proceedings: Control Theory and Applications}, volume = {151}, year = {2004}, pages = {6-12}, abstract = {

A design method for variable structure system control is presented. It is based on a differential geometric approach and it is intended to deal with the class of nonlinear systems affine in the control with uncertainties and disturbances. The main goals of the proposed method are: (i) robustness; (ii) tuning simplicity; (iii) chattering reduction; and (iv) reaching mode control. Its application to the wind subsystem of an electricity generation hybrid system is discussed in detail. Extensive simulation experiments were conducted with a comprehensive model of the plant and they are presented to illustrate the controller performance.

}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-1542686055\&partnerID=40\&md5=2557bb7e24e1921193c8cf3e6fd829c0}, author = {Valenciaga, Fernando and Puleston, Pablo F. and Battaiotto, Pedro E.} } @article {66, title = {{Control of the reaching mode in variable structure systems}}, journal = {{Latin American applied research}}, volume = {33}, year = {2003}, month = {10}, pages = {469 - 474}, abstract = {

This paper focuses on the behaviour of variable structure systems with dynamic control, particularly during the reaching mode of operation. It is shown that stability problems may arise during this reaching phase. The causes of these problems are closely related with the problems of windup commonly found in conventional control systems with actuator constraints. Methods for stabilization of the reaching mode are proposed which are based on the concepts of {\textquoteright}realizable reference{\textquoteright} and observers. Well-known algorithms that have been previously proposed from empiric ideas, can now be rigorously derived using these concepts. The theoretical framework developed by Kothare and co-workers in the context of windup is generalized to study and design control algorithms for the reaching mode.

}, issn = {0327-0793}, url = {http://www.scielo.org.ar/scielo.php?script=sci_arttext\&pid=S0327-07932003000400016\&nrm=iso}, author = {Mantz, Ricardo J. and De Battista, Hern{\'a}n and Bianchi, Fernando D. and Fern{\'a}ndez, Roberto. D.} } @article {67, title = {Energy-based approach to the output feedback control of wind energy systems}, journal = {International Journal of Control}, volume = {76}, year = {2003}, pages = {299-308}, abstract = {

Wind energy systems can be classified into constant speed and variable speed ones. In constant speed schemes, the generator is directly connected to the electric grid. On the other hand, variable speed operation can be accomplished interposing a static converter in the energy flow between the generator and the grid, permitting a high control flexibility. The main control objectives are the maximization of the conversion efficiency and the elimination of torque oscillations propagated through the drive train. It is assumed in this paper that the most flexible part of the system lies on the turbine, constraining the control solutions to generator speed feedback. The control task is addressed from a passivity-based control viewpoint. The drive train dynamics is modelled as a port-controlled Hamiltonian system with dissipation. Then, stabilization of the desired operating point is achieved through energy shaping and damping injection. Depending on the damping matrix assignment, different control solutions are recovered. Finally, a dynamic feedback controller which preserves the system structure is proposed to improve the system performance without measuring the wind velocity.

}, doi = {10.1080/0020717031000079373}, url = {http://dx.doi.org/10.1080/0020717031000079373}, author = {De Battista, Hern{\'a}n and Mantz, Ricardo J. and Christiansen, Carlos F.} } @article {108, title = {Power control of a solar/wind generation system without wind measurement: a passivity/sliding mode approach}, journal = {Energy Conversion, IEEE Transactions on}, volume = {18}, year = {2003}, month = {Dec}, pages = {501-507}, abstract = {

This paper deals with the control of the output power of a solar/wind stand-alone system. The control system regulates the generation of the wind subsystem in order to satisfy, jointly with the photovoltaic generation subsystem, the load and battery charge power demand. The controller is designed using a theoretical framework that unifies passivity and sliding mode techniques. The resultant control law does not need wind measurement and only relies on rotational speed and current measurements. An analysis of the acceleration estimate error is carried out and a countermeasure to compensate its effects is proposed. Finally, the performance of the controller is assessed through computer simulation, using a comprehensive nonlinear model of the plant.

}, keywords = {acceleration estimate error, angular velocity measurement, Battery charge measurement, Computer Simulation, control law, Control systems, controller design, Current measurement, current measurements, effects compensation, electric current measurement, hybrid power systems, nonlinear model, output power control, passivity/sliding mode approach, photovoltaic generation subsystem, photovoltaic power systems, Power control, power demand, Power generation, power generation control, Power measurement, rotational speed measurements, Sliding mode control, sliding mode techniques, Solar power generation, solar/wind generation system, stand-alone system, variable structure systems, Wind energy generation, wind generation subsystem control, Wind power generation, wind turbines}, issn = {0885-8969}, doi = {10.1109/TEC.2003.816602}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=1247775}, author = {Valenciaga, Fernando and Puleston, Pablo F. and Battaiotto, Pedro E.} } @article {69, title = {Sliding Mode Compensation for Windup and Direction of Control Problems in Two-Input-Two-Output Proportional-Integral Controllers}, journal = {Industrial \& Engineering Chemistry Research}, volume = {41}, year = {2002}, pages = {3179-3185}, abstract = {

The paper deals with the problems of windup and change in the direction of control in multi-input{\^a}{\textasciicircum}{\textquoteright}multi-output processes with actuator constraints. A sliding mode control is proposed to solve these problems for the case of two-input{\^a}{\textasciicircum}{\textquoteright}two-output proportional{\^a}{\textasciicircum}{\textquoteright}integral-controlled systems. The control strategy is based on the conditioning of the filtered references vector through a discontinuous action.

}, doi = {10.1021/ie010198b}, url = {http://dx.doi.org/10.1021/ie010198b}, author = {Mantz, Ricardo J. and De Battista, Hern{\'a}n} } @article {68, title = {Variable structure control of a photovoltaic energy converter}, journal = {Control Theory and Applications, IEE Proceedings -}, volume = {149}, year = {2002}, month = {Jul}, pages = {303-310}, abstract = {

The variable structure control of a DC-to-DC converter in photovoltaic applications is presented. The feasibility of establishing stable constant-voltage and constant-current sliding modes is stressed. Further, their ability to satisfy the control objectives, i.e. maximum power tracking or power regulation, is analysed. In addition, different control laws are obtained by combining these sliding motions, thereby improving their individual performances. The capability of these control laws to steer the state trajectories towards the sliding surfaces from any initial condition, as well as the stability of the sliding regimes, is investigated

}, keywords = {constant-current sliding modes, constant-voltage sliding modes, DC-DC power convertors, DC-to-DC converter, maximum power tracking, photovoltaic energy converter, photovoltaic power systems, power convertors, power regulation, state trajectories, Variable structure control, variable structure systems}, issn = {1350-2379}, doi = {10.1049/ip-cta:20020556}, url = {http://ieeexplore.ieee.org/xpl/abstractAuthors.jsp?arnumber=1039154}, author = {De Battista, Hern{\'a}n and Mantz, Ricardo J.} } @article {71, title = {A new approach to reaching mode of VSS using trajectory planning}, journal = {Automatica}, volume = {37}, year = {2001}, pages = {763 - 767}, abstract = {

This work deals with dynamic behavior of variable structure systems operating in reaching mode. Concepts of trajectory planning of differentially flat systems are employed to reach the sliding surface in a point where the sliding mode can be established. An additional control surface is proposed to track the planned trajectory. Then, the system evolves robustly from the initial state to the steady state. Adjusting the control action, undesirable transient behaviors are avoided and the state-space region in which the system operates safely is increased.

}, keywords = {variable structure systems}, issn = {0005-1098}, doi = {http://dx.doi.org/10.1016/S0005-1098(01)00012-7}, url = {http://www.sciencedirect.com/science/article/pii/S0005109801000127}, author = {Mantz, Ricardo J. and De Battista, Hern{\'a}n and Puleston, Pablo F.} } @article {70, title = {Performance analysis of a variable structure controller for power regulation of WECS operating in the stall region}, journal = {International Journal of Energy Research}, volume = {25}, year = {2001}, pages = {1345{\textendash}1357}, abstract = {

This paper deals with power regulation in variable speed wind energy conversion systems. The importance of power control in the stall region is stressed. This mode of operation is characterized by a non-minimum phase behaviour. A variable structure controller is described that provides stability by means of speed feedback and is robust to grid disturbances and model uncertainties. Performance of the controller is investigated. A compromise arises in the design of the speed feedback gain between high and low frequency wind components rejection. Furthermore, a cut-off frequency of the wind velocity measurement is obtained that minimizes the effect of turbulence on power regulation. Simulation results are presented, corroborating the features of the control strategy.

}, keywords = {energy conversion, Power control, variable structure systems, Wind energy}, issn = {1099-114X}, doi = {10.1002/er.758}, url = {http://dx.doi.org/10.1002/er.758}, author = {De Battista, Hern{\'a}n and Mantz, Ricardo J. and Christiansen, Carlos F.} } @article {109, title = {Power control of a photovoltaic array in a hybrid electric generation system using sliding mode techniques}, journal = {IEE Proceedings: Control Theory and Applications}, volume = {148}, year = {2001}, pages = {448-455}, abstract = {

A variable structure controller to regulate the output power of a standalone hybrid generation system is presented. The system comprises photovoltaic and wind generation, a storage battery bank and a variable monophasic load. The control law admits two modes of operation. The first takes place when the insolation regime is sufficient to satisfy the power demand. The second mode of operation takes place under insufficient insolation regimes. The latter leads the system operation at the maximum power operation point (MPOP) to save as much stored energy as possible. A new method based on the IncCond algorithm is developed. Sliding mode control techniques are used to design the control law. These techniques provide a simple control law design framework and contribute with their well known robustness properties. Finally, guidelines based on chattering considerations are given for the design of the practical system.

}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0035502897\&partnerID=40\&md5=5dfc41e00d8d47f4200fc32fa9aa06d7}, author = {Valenciaga, Fernando and Puleston, Pablo F. and Battaiotto, Pedro E.} } @mastersthesis {152, title = {Variable Structure Control of Hybrid Energy Generation Systems}, volume = {PhD}, year = {2001}, school = {Universidad Nacional de La Plata}, type = {PhD}, address = {La Plata, Buenos Aires, Argentina}, abstract = {Los sistemas de generaci{\'o}n basados en energ{\'\i}as renovables pueden ser clasificados de diversas maneras. Una de las formas posibles est{\'a} basada en su conectividad, permitiendo as{\'\i} diferenciarlos entre sistemas vinculados a la red de distribuci{\'o}n y sistemas aislados. El primer grupo se caracteriza en general por las elevadas potencias de generaci{\'o}n que involucra. Por su parte el segundo es m{\'a}s modesto en este sentido, estando habitualmente destinado a electrificar peque{\~n}as localidades aisladas de la red de distribuci{\'o}n. Estos {\'u}ltimos, conocidos como sistemas aut{\'o}nomos, emplean por lo general diversas formas de generaci{\'o}n en forma conjunta, siendo esta caracter{\'\i}stica la que les aporta el calificativo de "h{\'\i}bridos". El dise{\~n}o y control de este tipo de sistemas resulta t{\'e}cnicamente m{\'a}s complejo que el correspondiente a sistemas que simplemente tienden a aumentar la potencia disponible de infraestructuras ya existentes (Jayadev, 1995). Dentro de los sistemas h{\'\i}bridos aut{\'o}nomos, la tendencia actual consiste en determinar un control general que defina tanto la estrategia de operaci{\'o}n como las leyes de control a aplicar en cada caso, de manera de mejorar el desempe{\~n}o del sistema frente a un marco de operaci{\'o}n fuertemente aleatorio. En este sentido la presente tesis aborda esta problem{\'a}tica sobre un sistema h{\'\i}brido en particular. El objetivo propuesto consiste en controlar la magnitud de la potencia generada, de manera de satisfacer los requerimientos de una carga variante en el tiempo y, simult{\'a}neamente, proveer la potencia necesaria para seguir un ciclo de carga/mantenimiento especificado sobre su subsistema de almacenamiento de energ{\'\i}a. Esta estrategia permite extender la vida {\'u}til del subsistema de almacenamiento cuyo costo tiene un importante peso relativo sobre el precio total del sistema. Dadas las caracter{\'\i}sticas aleatorias de los fen{\'o}menos involucrados en la generaci{\'o}n y en la carga, el control debe considerar la operaci{\'o}n bajo diferentes combinaciones de disponibilidad de recursos (Grauers y Carlson, 1991; Mufti et al., 1998). El dise{\~n}o de las leyes de control se realiza bajo un marco te{\'o}rico que unifica aspectos del control por estructura variable con conceptos de pasividad (Sira-Ramirez y R{\'\i}os Bolivar, 1999). Este marco, permite conformar una metodolog{\'\i}a adecuada para abordar el dise{\~n}o de controladores de sistemas no lineales. Por su intermedio se obtienen leyes de control por realimentaci{\'o}n de estados conmutada que presentan varias propiedades atractivas.Entre ellas podr{\'\i}an citarse la robustez frente a ciertas incertidumbres param{\'e}tricas y a din{\'a}mica no modelada, buen rechazo a perturbaciones y l{\'\i}mites de conmutaci{\'o}n dependientes de los estados (Sira-Ramirez, 1988; Sira-Ramirez y R{\'\i}os Bolivar, 1999; Utkin, 1992 y 1993). Esta {\'u}ltima caracter{\'\i}stica permite disminuir la magnitud del chattering asociado a los reg{\'\i}menes deslizantes, mejorando as{\'\i} la regulaci{\'o}n sobre la salida del sistema que se desea controlar. Por {\'u}ltimo, es importante decir que si bien tanto el dise{\~n}o de la estrategia de operaci{\'o}n como el de las leyes de control se realiza sobre un sistema h{\'\i}brido aut{\'o}nomo particular, los fundamentos en que est{\'a} basado este dise{\~n}o pueden extrapolarse f{\'a}cilmente a otras topolog{\'\i}as.}, url = {http://sedici.unlp.edu.ar/handle/10915/1359}, author = {Valenciaga, Fernando} } @article {111, title = {An adaptive feedback linearization strategy for variable speed wind energy conversion systems}, journal = {International Journal of Energy Research}, volume = {24}, year = {2000}, pages = {151-161}, abstract = {

This paper presents a control strategy based on adaptive feedback linearization intended for variable speed grid-connected wind energy conversion systems (WECS). The proposed adaptive control law accomplishes energy capture maximization by tracking the wind speed fluctuations. In addition, it linearizes the system even in the presence of turbine model uncertainties, allowing the closed-loop dynamic behaviour to be determined by a simple tuning of the controller parameters. Particularly, the attention is focused on WECS with slip power recovery, which use a power conversion stage as a rotor-controlled double-output induction generator. However, the concepts behind the proposed control strategy are general and can be easily extended to other WECS configurations. Copyright {\^A}{\textcopyright} 2000 John Wiley \& Sons, Ltd.

}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0034144197\&partnerID=40\&md5=6c28e3350c1d9271060638a4e8a78155}, author = {Valenciaga, Fernando and Puleston, Pablo F. and Battaiotto, Pedro E. and Mantz, Ricardo J.} } @article {72, title = {Dynamical sliding mode power control of wind driven induction generators}, journal = {Energy Conversion, IEEE Transactions on}, volume = {15}, year = {2000}, month = {Dec}, pages = {451-457}, abstract = {

This paper concerns power regulation of variable-speed wind energy conversion systems. These systems have two regions of operation, depending on the tip speed ratio of the wind turbines. They are distinguished by a minimum phase behavior in one of these regions and a nonminimum phase one in the other. A sliding mode control strategy is proposed that assures stability in both regions of operation and imposes the ideally designed feedback control solution in spite of model uncertainties. Moreover, power regulation by the proposed sliding control in the minimum phase region is completely robust to wind disturbances and parameter uncertainties

}, keywords = {asynchronous generators, Control systems, dynamical sliding mode power control, feedback, ideally designed feedback control solution, Induction generators, machine control, minimum phase behavior, minimum phase region, model uncertainties, nonminimum phase region, parameter uncertainties, Power control, Power generation, power regulation, Power system modeling, Robustness, Sliding mode control, stability, tip speed ratio, variable speed gear, variable structure systems, variable-speed wind energy conversion systems, wind disturbances, wind driven induction generators, Wind energy, Wind energy generation, Wind power generation, wind turbines}, issn = {0885-8969}, doi = {10.1109/60.900507}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=900507}, author = {De Battista, Hern{\'a}n and Mantz, Ricardo J. and Christiansen, Carlos F.} } @article {73, title = {Harmonic series compensators in power systems: their control via sliding mode}, journal = {Control Systems Technology, IEEE Transactions on}, volume = {8}, year = {2000}, month = {Nov}, pages = {939-947}, abstract = {

This paper deals with harmonic current compensation in power systems using shunt passive and series active filters. It is shown how constraints of the active filters can notoriously degrade the performance of the compensating system. The use of variable structure system theory is suggested for analysis and design of series active filters. Sliding mode control strategies to improve harmonic rejection are proposed, and active filters with different switching-ripple filters are considered. These control strategies provide robustness to active filter modeling errors and external disturbances

}, keywords = {active filters, compensation, Control systems, Degradation, harmonic series compensation, Power harmonic filters, Power system analysis computing, power system control, power system harmonics, power systems, Robustness, Sliding mode, Sliding mode control, variable structure system, variable structure systems}, issn = {1063-6536}, doi = {10.1109/87.880597}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=880597}, author = {De Battista, Hern{\'a}n and Mantz, Ricardo J.} } @article {110, title = {Passivity/sliding mode control of a stand-alone hybrid generation system}, journal = {IEE Proceedings: Control Theory and Applications}, volume = {147}, year = {2000}, pages = {680-686}, abstract = {

A novel variable structure controller for an electric generation hybrid system is proposed. The system is intended for variable alternate load and includes a wind turbine, photovoltaic generation and a battery bank. As a first step for the controller design, a dynamic model of the system is developed in a rotor reference frame. The control law is designed through the combination of passivity and sliding mode techniques. The objective is to control the operation of the wind subsystem to complement the photovoltaic generation, so the power demand is satisfied. During periods of scarce winds, the strategy is modified and the control objective becomes maximum wind generation.

}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0034313644\&partnerID=40\&md5=44f973c64683c72ac78b96131dcf6c83}, author = {Valenciaga, Fernando and Puleston, Pablo F. and Battaiotto, Pedro E. and Mantz, Ricardo J.} } @mastersthesis {154, title = {Power Quality Control in Wind Energy Conversion Systems}, volume = {PhD}, year = {2000}, school = {Universidad Nacional de La Plata}, type = {PhD thesis}, address = {La Plata, Buenos Aires, Argentina}, abstract = {Reconocidas las bondades de la energ{\'\i}a e{\'o}lica, la tendencia actual es la investigaci{\'o}n de estrategias de control que permitan mejorar el desempe{\~n}o del sistema de conversi{\'o}n. El control puede realizarse sobre la turbina o sobre el generador el{\'e}ctrico. El control de la orientaci{\'o}n de la turbina, o de sus palas, presenta severas restricciones debido al ancho de banda limitado de los actuadores y los esfuerzos sobre las partes mec{\'a}nicas m{\'o}viles. El control del generador, en cambio, se realiza sobre el subsistema el{\'e}ctrico, por lo que es notablemente m{\'a}s vers{\'a}til y confiable que el anterior (Leith y Leithead, 1997; Ekelund, 1997; Novak, 1995). La presente tesis aborda el problema de control del generador. Los objetivos de control son la optimizaci{\'o}n del rendimiento de conversi{\'o}n y, al mismo tiempo, la reducci{\'o}n de los efectos de las cargas aerodin{\'a}micas sobre la red el{\'e}ctrica. Asimismo, se propone una estrategia de control para limitar la potencia suministrada a la red, tanto por seguridad del sistema mec{\'a}nico como por cuestiones asociadas a la calidad de potencia. Por otro lado, se trata la compensaci{\'o}n del sistema de conversi{\'o}n con filtros activos. {\'E}sta tiene el prop{\'o}sito de complementar el mejoramiento de la calidad de potencia obtenido mediante el control del generador.Las estrategias de control propuestas se enmarcan dentro del control de estructura variable y sus reg{\'\i}menes deslizantes asociados. El control de estructura variable es particularmente apropiado para el control de sistemas de potencia que, por razones de eficiencia, emplean dispositivos electr{\'o}nicos operando como llaves. Adem{\'a}s, el control por modo deslizante tiene interesantes propiedades de robustez a incertidumbres en los par{\'a}metros del sistema, alta capacidad de rechazo a perturbaciones y ofrece un marco propicio para el control de sistemas no lineales complejos (Utkin, 1977; Utkin, 1993; Sira-Ram{\'\i}rez, 1988). La presente tesis est{\'a} orientada al control de sistemas de velocidad variable conectados a red que emplean generador asincr{\'o}nico de doble salida y recuperaci{\'o}n de la potencia de resbalamiento. Sin embargo, la mayor{\'\i}a de los conceptos son directamente aplicables a otras configuraciones de sistemas de conversi{\'o}n de energ{\'\i}a e{\'o}lica. La configuraci{\'o}n considerada en esta tesis presenta aspectos atractivos como generaci{\'o}n a tensi{\'o}n y frecuencia de red, generaci{\'o}n por encima de la potencia nominal de la m{\'a}quina el{\'e}ctrica, empleo de convertidores comparativamente peque{\~n}os y baratos dado que s{\'o}lo procesan una fracci{\'o}n de la potencia generada (Ermis et al., 1992; Smith y Donegani, 1986; {\c C}adirci y Ermis, 1992; Salameh y Kazda, 1986).}, url = {http://sedici.unlp.edu.ar/handle/10915/1355}, author = {De Battista, Hern{\'a}n} } @article {112, title = {Sliding mode control for efficiency optimization of wind energy systems with double output induction generator}, journal = {International Journal of Energy Research}, volume = {24}, year = {2000}, pages = {77-92}, abstract = {

This paper deals with generation efficiency maximization of wind energy conversion systems (WECS) with double output induction generator (DOIG). In the first place, to design a sliding mode controller, an apropos model of the DOIG with electronic drive in the rotor is developed. Then, conditions of maximum power generation are obtained. Finally, a sliding mode control strategy for this type of WECS is presented. The proposed strategy varies the firing angle of the electronic drive in order to set the extreme control values equal to the maximum and minimum available control action of the system. Consequently, robustness to parametric uncertainties and external disturbances is maximised. Copyright {\^A}{\textcopyright} 2000 John Wiley \& Sons, Ltd.

}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-0034058150\&partnerID=40\&md5=eba298a91b1d03fc3e477dc6b9c59b18}, author = {Puleston, Pablo F. and Mantz, Ricardo J. and Battaiotto, Pedro E. and Valenciaga, Fernando} } @article {74, title = {Sliding mode control of wind energy systems with DOIG-power efficiency and torsional dynamics optimization}, journal = {Power Systems, IEEE Transactions on}, volume = {15}, year = {2000}, month = {May}, pages = {728-734}, abstract = {

Wind turbines with double output induction generators can operate at variable speed permitting conversion efficiency maximization over a wide range of wind velocities. However, random wind fluctuations, wind shear and tower shadow, may excite the oscillation mode of the mechanical system, producing large torque ripple. Consequently, damage to drive train components and power quality problems may occur. In this paper, a sliding mode control is developed which provides a suitable compromise between conversion efficiency and torque oscillation smoothing. The resultant sliding dynamics is completely robust to uncertainties in the electrical variables and parameters. In addition, to prevent windup problems due to saturation, a combined sliding surface that incorporates such limitations is proposed

}, keywords = {asynchronous generators, combined sliding surface, conversion efficiency maximization, double output induction generators, drive train components, electrical variables uncertainties, Fluctuations, Induction generators, large torque ripple, machine control, mechanical system, Mechanical systems, oscillation mode excitation, oscillations, Poles and towers, power efficiency, power generation control, Power quality, power quality problems, power supply quality, random wind fluctuations, resultant sliding dynamics, Sliding mode control, Torque, torque oscillation smoothing, torsion, torsional dynamics optimization, tower shadow, uncertainties robustness, variable speed, variable speed gear, variable structure systems, Wind energy, wind energy systems, wind shear, Wind speed, wind turbines}, issn = {0885-8950}, doi = {10.1109/59.867166}, url = {http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=867166}, author = {De Battista, Hern{\'a}n and Puleston, Pablo F. and Mantz, Ricardo J. and Christiansen, Carlos F.} } @article {75, title = {Output overshoots in systems with integral action operating in sliding mode}, journal = {Automatica}, volume = {35}, year = {1999}, pages = {1141 - 1147}, abstract = {

This paper deals with the pole assignment technique in systems with integral action and sliding mode control. It is known that, because of the order reduction provided by the sliding mode, one gain of the sliding surface that determines the pole placement can be freely selected. In this paper the existence of a direct connection between this gain and an integral wind up behavior is demonstrated. A sufficient condition for the existence of this problem is obtained. A control strategy based on the appropriate selection of the aforesaid free gain is proposed. Two examples are presented.

}, keywords = {Integral action}, issn = {0005-1098}, doi = {http://dx.doi.org/10.1016/S0005-1098(99)00019-9}, url = {http://www.sciencedirect.com/science/article/pii/S0005109899000199}, author = {Mantz, Ricardo J. and Puleston, Pablo F. and De Battista, Hern{\'a}n} }