Artículos de publicaciones periódicas

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Complexity reduction of piecewise affine linear parameter varying controllers
(2024-05-03) Bianchi, Fernando D.; Sánchez-Peña, Ricardo S.
This work analyzes the design and implementation of piecewise affine (PWA) Linear Parameter Varying (LPV) controllers. PWA-LPV models can be employed to describe complex nonlinear or time-varying systems with the aim of control design. The complexity of a PWA-LPV controller depends on the number of local models used to describe the plant. Here we propose a methodology to reduce this number and thus simplify the design and implementation complexity of the resulting controller without a significant performance degradation. The methodology is illustrated by an academic example and a more realistic wind turbine control application.
H∞ control experiments for increasing H2 purity in high-pressure alkaline electrolyzers
(2024) David, Martín; Bianchi, Fernando D.; Ocampo-Martínez, Carlos; Sánchez-Peña, Ricardo
In this paper, an H∞ control strategy is implemented in a prototype alkaline electrolyzer to maintain equalized the liquid levels in the separations chambers while following a pressure reference. The aim is to minimize the contamination of the gases produced by the electrolyzer. To this end, two outlet valves are controlled in the output lines of both gases: H2 and O2. The performance of the proposed control strategy was experimentally evaluated under different operating conditions. In all cases, H2 contamination in O2 was below 0.2%.
Online adjustable linear parameter-varying controller for artificial pancreas systems
(Elsevier, 2023-06) Bianchi, Fernando D.; Sánchez-Peña, Ricardo; Garelli, Fabricio
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.
Towards an experimental control of neural activity: The Wilson-Cowan model
(IFAC-PapersOnLine, 2022) Martinez, Sebastián; Sánchez-Peña, Ricardo; Belluscio, Mariano; Piriz, Joaquín; Garcia-Violini, Demián
The prospect of modifying neural activity in a principled way, could facilitate the understanding of brain functions and the development of medical treatments. To predict the dynamics that underlie the different brain activities, several neurobiological models have been proposed, either focusing on individual cells or whole populations. In this context, control systems are a powerful tool to provide a correct articulation between inputs, i.e. neural stimuli, and observables, i.e. system outcomes. Based on well-established neurobiological hypotheses, this study presents a control framework to regulate a neural-mass activity, with potential uses for pattern tracking, such as, rhythm evoking and phase synchronisation. Being these mechanisms closely connected with real brain computations, this study is carried out using a meaningful perspective in terms of biological interpretation. To this end, the Wilson-Cowan model is used, where the input stimuli is elicited through light signals applied to genetically modified neurons that express light-gated actuators. Thus, this study states a crucial proof of concept towards a future experimental application of the control framework for neurobiological systems.
Non-pharmaceutical intervention to reduce COVID-19 impact in Argentina
(2022-05) García Violini, Demián; Sánchez-Peña, Ricardo; Moscoso-Vásquez, Marcela; Garelli, Fabricio
"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."
Dynamical models in neuroscience from a closed-loop control perspective
(2022-01-28) Martínez, Sebastián; García Violini, Demián; Belluscio, Mariano; Piriz, Joaquin; Sánchez-Peña, Ricardo
"Modifying neural activity is a substantial goal in neuroscience that facilitates the understanding of brain functions and the development of medical therapies. Neurobiological models play an essential role, contributing to the understanding of the underlying brain dynamics. In this context, control systems represent a fundamental tool to provide a correct articulation between model stimulus (system inputs) and outcomes (system outputs). However, throughout the literature there is a lack of discussions on neurobiological models, from the formal control perspective. In general, existing control proposals applied to this family of systems, are developed empirically, without theoretical and rigorous framework. Thus, the existing control solutions, present clear and significant limitations. The focus of this work is to survey dynamical neurobiological models that could serve for closed-loop control schemes or for simulation analysis. Consequently, this paper provides a comprehensive guide to discuss and analyze control oriented neurobiological models. It also provides a potential framework to adequately tackle control problems that could modify the behavior of single neurons or networks. Thus, this study constitutes a key element in the upcoming discussions and studies regarding control methodologies applied to neurobiological systems, to extend the present research and understanding horizon for this field."
Control no-híbrido de glucemia ensayado en pacientes ambulatorios con Diabetes Tipo 1
(2022-07) Garelli, Fabricio; Fushimi, Emilia; Rosales, Nicolás; Arambarri, Delfina; Serafini, María Cecilia; De Battista, Hernán; Grosembacher, Luis; Sánchez-Peña, Ricardo
"En este trabajo se presenta la experiencia argentina en el problema de regulación de los niveles de glucosa en sangre para pacientes con Diabetes Mellitus Tipo 1 (insulino-dependientes), denominado Páncreas Artificial. El grupo de trabajo ha realizado 3 pruebas clínicas, las primeras en Latinoamérica. Las dos primeras fueron concretadas en 2016 y 2017, ambas en el Hospital Italiano de Buenos Aires (HIBA) con 5 pacientes adultos durante 36 hs. En la segunda de ellas se utilizó 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 combinación con una capa de seguridad llamada SAFE (Safety Auxiliary Feedback Element). Más recientemente y en plena pandemia de COVID-19 se llevó a cabo la primera prueba ambulatoria, realizada en 2021 en un hotel con 5 pacientes durante 6 días. En esta tercera prueba además, se utilizó una plataforma desarrollada por la Universidad Nacional de La Plata (UNLP), denominada InsuMate. Ésta conecta el celular con la bomba de insulina y el monitor de glucosa, aloja el algoritmo de control y permite el monitoreo remoto de múltiples pacientes. Los resultados obtenidos sugieren que el uso del algoritmo ARG en forma ambulatoria es factible, seguro y eficaz en comparación con la terapia usual. Asimismo, la plataforma InsuMate resultó ser intuitiva y sencilla para los usuarios, tanto médicos como pacientes participantes del ensayo, logrando un tiempo de funcionamiento del lazo cerrado superior al 95 %."
Classification based on dynamic mode decomposition applied to brain recognition of context
(2021-09) Martínez, Sebastián; Silva, Azul; García Violini, Demián; Piriz, Joaquin; Belluscio, Mariano; Sánchez-Peña, Ricardo
"Local Field Potentials (LFPs) are easy to access electrical signals of the brain that represent the summation in the extracellular space, of currents originated within the neurons. As such, LFPs could contain infor mation about ongoing computations in neuronal circuits and could potentially be used to design brain machine interface algorithms. However how brain computations could be decoded from LFPs is not clear. Within this context, a methodology for signal classification is proposed in this study, particularly based on the Dynamic Mode Decomposition method, in conjunction with binary clustering routines based on supervised learning. Note that, although the classification methodology is presented here in the context of a biological problem, it can be applied to a broad range of applications. Then, as a case-study, the proposed method is validated with the classification of LFP-based brain cognitive states. All the analysis, signals, and results shown in this study consider real data measured in the hippocampus, in rats perform ing exploration tasks. Consequently, it is shown that, using the measured LFP, the method infers which context was the animal exploring. Thus, evidence on the spatial codification in LFP signals is consequently provided, which still is an open question in neuroscience."
First outpatient clinical trial of a full closed-loop artificial pancreas system in South America
(2022-05) Garelli, Fabricio; Fushimi, Emilia; Rosales, Nicolás; Arambarri, Delfina; Mendoza, Leandro; Serafini, María Cecilia; Moscoso-Vásquez, Marcela; Stasi, Marianela; Duette, Patricia; García Arabehety, Julia; Giunta, Javier; De Battista, Hernán; Sánchez-Peña, Ricardo; Grosembacher, Luis
"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."
A method for reducing implementation complexity in linear parameter-varying controllers
(2022-12) Bianchi, Fernando D.; Sánchez-Peña, Ricardo
"Gain-scheduling is a popular control technique to deal with nonlinear and time varying systems. The linear parameter-varying (LPV) system approach offers systematic tools to design gain-scheduled controllers. However, the implementation of these controllers might demand complex mathematical operations to be performed in real-time. This limits the hardware and the applications in which LPV controllers can be used. In this article, we analyze these limitations and propose a design methodology to reduce the implementation complexity of gain-scheduled LPV controllers. The methodology is illustrated with a nonlinear bicycle model used in electric vehicle control."
LPV control of a magnetic bearing experiment
(2010-10) Ghersin, Alejandro S.; Smith, R. S.; Sánchez-Peña, Ricardo
"An LPV (Linear Parameter Varying) controller design example for a Magnetic Bearing System is presented. A linear model of the system including bending modes and imbalance is described. Simulations and experimental results show the usefulness of the LPV method with eigenvalue clustering constraints in spite of the limited rotation rate range. The results show that this method facilitates simulation and allows implementation. Conclusions are drawn on the limited range for the rotation rate the LPV controller allows for."
A novel design approach for switched LPV controllers
(2022-07-22) Bianchi, Fernando D.; Sánchez-Peña, Ricardo
"A novel design procedure for switched linear parameter-varying (LPV) controller is proposed. The new procedure, based on the Youla parameterisation ideas, decomposes the controller design into two steps. One focuses on ensuring global stability and the other on fulfilling the local performance specifications. This scheme allows the design of each local controller independently of each other, which may achieve higher performance without compromising the global stability and also simplifies the synthesis and the implementation of the local controllers. Any standard LPV synthesis procedure can be used to design these controllers. On the other hand, the stability during switching is ensured with convex constraints and no restrictions are imposed on the switching among controllers. The use of the proposed procedure is illustrated with an active magnetic bearing example."
Applied LPV Control with Full Block Multipliers and Regional Pole Placement
(2010-05) Sánchez-Peña, Ricardo; Ghersin, Alejandro S.
"A formulation of an LPV control problem with regional pole placement constraints is presented, which is suitable for the application of a Full Block S-Procedure. It is demonstrated that improved bounds can be obtained on the induced 𝐿2 norm of closed loop systems, while satisfying pole placement constraints. An application consisting in the 6 degrees of freedom (DOF) control of a space vehicle is developed as an example, with hardware in the loop (HIL) simulation. This shows that the method is appealing from the practical point of view, considering that the synthesized control law can be implemented satisfactorily in standard flight control systems. Conclusions with remarks towards the practical use of the method are presented as well."
Distributed data-driven UAV formation control via evolutionary games: experimental results
(2021-07) Barreiro-Gomez, Julian; Mas, Ignacio; Giribet, Juan I.; Moreno, Patricio; Ocampo-Martínez, Carlos; Sánchez-Peña, Ricardo; Quijano, Nicanor
"This work proposes a novel data-driven distributed formation-control approach based on multi-population evolutionary games, which is structured in a leader-follower scheme. The methodology considers a time-varying communication graph that describes how the multiple agents share information to each other. We present stability guarantees for configurations given by time-varying interaction networks, making the proposed method suitable for real-world problems where communication constraints change along the time. Additionally, the proposed formation controller allows for an agent to leave or enter the group without the need to modify the behaviors of other agents in the group. This game-theoretical approach is evaluated through numerical simulations and real outdoors experimental results using a fleet of aerial autonomous vehicles, showing the control performance."
Active noise hybrid time-varying control for motorcycle helmets
(2010-05) Castañé-Selga, Rosa; Sánchez-Peña, Ricardo
"Recent noise at work regulations in the EU (2003) have been established to prevent noise induced hearing loss (NIHL). This imposes better performance results to traditional feedback active noise control (ANC) in motorcycle helmets, which suffer from well known limitations. Here two new ideas are applied to this problem. First, an hybrid (feedforward/feedback) linear time invariant (LTI) controller is designed for a motorcycle helmet ANC, which improves the resulting attenuation. This is achieved by adding an extra pair of microphones which measure the external noise that is then used as the feedforward input signal. In addition and to increase even more the resulting performance, the air velocity is measured in real-time and used as the parameter which schedules a linear parameter varying (LPV) feedback (FB) controller. This is combined with the previous feedforward (FF) controller, resulting in a time-varying hybrid controller. Both hybrid, LTI and LPV controllers are designed using linear matrix inequality (LMI)-based optimization. Two experiments have been carried out to measure the relation between external noise spectra and velocity: a wind tunnel test and a freeway ride experience. The resulting controllers are tested in a simulation which uses actual data obtained from the freeway experiment. The resulting attenuations in this motivating study seem promising for future controller tests to be performed in real-time, with the adequate hardware."
Remote glucose monitoring platform for multiple simultaneous patients at coronavirus disease 2019 intensive care units: case report including adults and children
(2021) Garelli, Fabricio; Rosales, Nicolás; Fushimi, Emilia; Arambarri, Delfina; Mendoza, Leandro; De Battista, Hernán; Sánchez-Peña, Ricardo; García Arabehety, Julia; Distefano, Sabrina; Barcala, Consuelo; Giunta, Javier; Las Heras, Marcos; Martínez Mateu, Carolina; Prieto, Mariana; San Román, Eduardo; Krochik, Gabriela; Grosembacher, Luis
Reducing glucose variability due to meals and postprandial exercise in TI DM using switched LPV control: in silico studies
(2016) Colmegna, Patricio; Sánchez-Peña, Ricardo; Gondhalekar, Ravi; Dassau, Eyal; Doyle III, Frank J.
"Time-varying dynamics is one of the main issues for achieving safe blood glucose control in type I diabetes mellitus (TI DM) patients. In addition, the typical disturbances considered for controller design are meals, which increase the glucose level, and physical activity (PA), which increases the subject's sensitivity to insulin. In previous works the authors have applied a linear parameter-varying (LPV) control technique to manage unannounced meals."
Switched LPV glucose control in type 1 diabetes
(2016-06) Colmegna, Patricio; Sánchez-Peña, Ricardo; Gondhalekar, Ravi; Dassau, Eyal; Doyle III, Frank J.
"The purpose of this work is to regulate the blood glucose level in Type 1 Diabetes Mellitus (T1DM) patients with a practical and flexible procedure that can switch amongst a finite number of distinct controllers, depending on the user´s choice."
Online guidance updates using neural networks
(2010) Filici, Cristian; Sánchez-Peña, Ricardo
"The aim of this article is to present a method for the online guidance update for a launcher ascent trajectory that is based on the utilization of a neural network approximator. Generation of training patterns and selection of the input and output spaces of the neural network are presented, and implementation issues are discussed. The method is illustrated by a 2-dimensional launcher simulation."
Non-pharmaceutical intervention to reduce COVID-19 impact in Argentina
(2021-06-21) García Violini, Demián; Sánchez-Peña, Ricardo; Moscoso-Vásquez, Marcela; Garelli, Fabricio
"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."

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