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Ponencia en Congreso Application of robust control to a cryogenic current comparator(2016-07) Bierzychudek, Marcos E.; Götz, Martin; Sánchez-Peña, Ricardo; Tonina, Alejandra; Iuzzolino, Ricardo; Drung, Dietmar"We describe the design and implementation of an H ∞ controller for PTB's 14-bit cryogenic current comparator (CCC). Measurement results obtained using either the newly implemented digital H ∞ controller or the conventional analog integrator are consistent. In a wide frequency range, the system's noise figure is improved when using the new controller."Ponencia en Congreso LPV control of glucose for diabetes type I(2010) Sánchez-Peña, Ricardo; Ghersin, Alejandro S."This paper considers the problem of automatically controlling the glucose level in a Diabetes type I patient. Three issues have been considered: model uncertainty, timevarying/nonlinear phenomena and controller implementation. To that end, the dynamical model of the insulin/glucose relation is framed as a Linear Parameter Varying system and a controller is designed based on it. In addition, this framework allows not only a better performance than other classical methods, but also provides stability and performance guarantees. Design computations are based on convex Linear Matrix Inequality (LMI) optimization. Implementation is based on a low order controller whose dynamics adapts according to the glucose levels measured in real-time."Ponencia en Congreso Control-oriented linear parameter-varying model for glucose control in type 1 diabetes(2016) Colmegna, Patricio; Sánchez-Peña, Ricardo; Gondhalekar, Ravi"The contribution of this paper is a controller design oriented model of insulin-glucose dynamics in Type 1 Diabetes Mellitus (T1DM). The novelty of the proposed model is to more effectively include the time-varying nature, and also the inter-patient variability, associated with the glucose control problem. Importantly, this is achieved in a manner that straightforwardly facilitates well-known and standard controller synthesis procedures. In that way, an average Linear Parameter-Varying (LPV) model that captures the dynamics from the insulin delivery input to the subcutaneous-glucose concentration output is constructed based on the Universities of Virginia (UVA)/Padova metabolic simulator. In addition, a system-oriented reinterpretation of the classical ad-hoc 1800 rule is applied to adapt the model’s gain."Ponencia en Congreso H2 purity control of high-pressure alkaline electrolyzers(2021-06) David, Martín Rafael; Bianchi, Fernando D.; Ocampo-Martínez, Carlos; Sánchez-Peña, Ricardo"This paper proposes a control strategy that mitigates the cross contamination of H2 and O2 in a high-pressure alkaline electrolyzer, which consequently increases the supplied gases purity. In order to reduce the diffusion of gases through the membrane, the controller establishes the opening of two outlet valves based on the pressure of the system and the difference in liquid level between both separation chambers. Therefore, a multiple input - multiple output optimal controller is designed here. For this purpose, an available high-fidelity model was simplified in order to obtain a control-oriented model. The proposed controller was evaluated in simulation using the high-fidelity nonlinear model in a wide operating range and was compared with a pair of decoupled PI controllers. The resulting impurity of gases was below 1% in all cases."Ponencia en Congreso Distributed formation control of multiple unmanned aerial vehicles over time-varying graphs using population games(2016-12) Barreiro-Gomez, Julian; Mas, Ignacio; Ocampo-Martínez, Carlos; Sánchez-Peña, Ricardo; Quijano, Nicanor"This paper presents a control technique based on distributed population dynamics under time-varying communication graphs for a multi-agent system structured in a leader-follower fashion. Here, the leader agent follows a particular trajectory and the follower agents should track it in a certain organized formation manner. The tracking of the leader can be performed in the position coordinates x, y, and z, and in the yaw angle φ. Additional features are performed with this method: each agent has only partial knowledge of the position of other agents and not necessarily all agents should communicate to the leader. Moreover, it is possible to integrate a new agent into the formation (or for an agent to leave the formation task) in a dynamical manner. In addition, the formation configuration can be changed along the time, and the distributed population-games-based controller achieves the new organization goal accommodating conveniently the information-sharing graph in function of the communication range capabilities of each UAV. Finally, several simulations are presented to illustrate different scenarios, e.g., formation with time-varying communication network, and time-varying formation."Ponencia en Congreso Phenomenological based model of hydrogen production using an alkaline self-pressurized electrolyzer(2019-08) David, Martín Rafael; Álvarez, Hernán; Ocampo-Martínez, Carlos; Sánchez-Peña, Ricardo"The aim of this work is to develop the phenomenological based modeling of a self-pressurized alkaline electrolyser with the objective of predicting the cross-contamination of the gases produced. A proposed model, built in Matlab ® , represents the dynamical evolution in real electrolysers, and anticipates operational variables: level, pressure and all concentrations. Dynamic responses in the concentrations of the electrolytic cell, and variations in both level and pressure at the chamber due to the change in current and diffusivity, are reported. The equations by which the variables can be computed are also presented. The proposed model is ready for the corresponding adjustment of parameters based on experimental measurements taken from an available prototype and through a suitable identification process."Ponencia en Congreso Unannounced meal analysis of the ARG algorithm(2019-07) Fushimi, Emilia; Colmegna, Patricio; De Battista, Hernán; Garelli, Fabricio; Sánchez-Peña, Ricardo"One of the main challenges in automatic glycemic regulation in patients with type 1 diabetes (T1D) is to dispense with carbohydrate counting. In this context, we propose to equip a previously introduced switched Linear Quadratic Gaus-sian (LQG) controller—the so-called Automatic Regulation of Glucose (ARG) algorithm—with an automatic switching signal generator (SSG). The ARG algorithm not only regulates the basal insulin infusion rate but also generates feedback insulin spikes at meal times, i.e., no open-loop insulin boluses are needed to mitigate postprandial glucose excursions. However, in its former version, it was required to announce the meal time. In this work, the performance of the ARG algorithm combined with the proposed SSG is assessed in silico with unannounced meals. In addition, the response of the SSG is estimated using clinical data obtained with the ARG algorithm in the first-ever artificial pancreas (AP) trials carried out in Latin America."Ponencia en Congreso Artificial Pancreas: first clinical trials in Argentina(2017-07) Sánchez-Peña, Ricardo; Colmegna, Patricio; Grosembacher, Luis; Breton, Marc; De Battista, Hernán; Garelli, Fabricio; Belloso, Waldo H.; Campos-Náñez, Enrique; Simonovich, Ventura; Beruto, Valeria; Scibona, Paula; Cherñavvsky, Daniel"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'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."Ponencia en Congreso Application of robust control to a cryogenic current comparator(2017-06) Bierzychudek, Marcos E.; Götz, Martin; Sánchez-Peña, Ricardo; Iuzzolino, Ricardo; Drung, Dietmar"This paper describes the implementation of a digital robust controller in a cryogenic current comparator. The controller was designed applying H∞ control theory and it was programmed in a home-made digital unit. Experimental comparisons of the new robust controller with the conventional analog integrator have showed a significant improvement of stability robustness and noise rejection in the system."Ponencia en Congreso Closed-loop in neuroscience: can a brain be controlled?(2018) García Violini, Demián; Bertone-Cueto, Nicolás I.; Martínez, Sebastián; Chiesa Docampo, Franco; de la Fuente, Verónica; Belluscio, Mariano; Piriz, Joaquín; Sánchez-Peña, Ricardo"An experimental setup capable of stimulating, inhibiting, sensing, processing and analyzing a iological system is presented. The experimental setup is based on open-source, open hardware commercial devices. It can be applied to record and control neuronal activity, for example to stablish causal links between neurons and behavior in a closed-loop fashion. Cells or group of cells can be triggered by acoustical, electrical or light impulses. This last case is based on a technique defined as optogenetics. The latter is used in an example that reads and controls neuronal activity of a population of neurons in laboratory rats forcing them to transition between neuronal states, illustrates the system developed in this work. Index Terms—Optogenetics, closed-loop, automatic control, open-source, open-hardware."Ponencia en Congreso Real time stable identification: A Nehari/SOS approach(2007) García Galiñanes, Rafael; Sánchez-Peña, Ricardo; Mancilla-Aguilar, J. L."Here we present an adaptive identification algorithm based on Second Order section (SOS) model structures. The procedure guarantees stable transfer functions whenever the actual physical plant is stable, due to an optimal Nehari approximation step performed analytically. The procedure is suitable to be implemented in real time applications. Some examples illustrate the proposed algorithm."