Artículos de publicaciones periódicas

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Automatic glucose control during meals and exercise in type 1 diabetes: proof-of-concept in silico tests using a switched LPV approach
(2021) Colmegna, Patricio; Bianchi, Fernando D.; Sánchez-Peña, Ricardo
"Keeping the blood glucose levels within the safe range during meals and exercise still represents a major hurdle not only for patients with type 1 diabetes (T1D), but also for Artificial Pancreas (AP) systems. One of the reasons a fully (autonomous) closed-loop solution has not been released onto the market yet is the slow action of current insulin analogs. To partially overcome this limitation, the authors have previously designed a switched control strategy equipped with an insulin-on-board (IOB) safety loop that mitigates meal-related glucose excursions without carbohydrate counting. In this paper, a similar strategy based on a Linear Parameter-Varying (LPV) control law has been adapted to safely handle also exercise challenges with minimum user intervention. In silico results using the UVA/Padova simulator evidence that the proposed closedloop scheme is feasible under moderate-intense exercise bouts by effectively and safely reducing the risk of hypoglycemia."
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.
Data-driven fault diagnosis and robust control: application to PEM fuel cell systems
(2018-08) Ocampo-Martínez, Carlos; Sánchez-Peña, Ricardo; Bianchi, Fernando D.; Ingimundarson, Ari
"A data-driven methodology that includes the unfalsified control concept in the framework of fault diagnosis and isolation (FDI) and fault-tolerant control (FTC) is presented. The selection of the appropriate controller from a bank of controllers in a switching supervisory control setting is performed by using an adequate FDI outcome. By combining simultaneous online performance assessment of multiple controllers with the fault diagnosis decision from structured hypothesis tests, a diagnosis statement regarding what controller is most suitable to deal with the current (nominal or faulty) mode of the plant is obtained. Switching strategies that use the diagnosis statement are also proposed. This approach is applied to a nonlinear experimentally validated model of the breathing system of a polymer electrolyte membrane fuel cell. The results show the effectiveness of this FDI–fault-tolerant control data-driven methodology."
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%.
Invalidation and low-order model set for artificial pancreas robust control design
(2019) Bianchi, Fernando D.; Moscoso-Vásquez, Marcela; Colmegna, Patricio; Sánchez-Peña, Ricardo
"The purpose of this work is to compute a linear parameter-varying (LPV) model set that describes the insulin-glucose dynamics in type 1 diabetes (T1D). This set includes a nominal LPV model and dynamic uncertainty and is amenable to controller design. The nominal model is an LPV control-oriented model previously published by the authors that is (in)validated in this work against the UVA/Padova metabolic simulator. The result is a set of models that is used to design a switched LPV robust controller to account for nonlinearities and variations in insulin sensitivity (SI). Closed-loop responses obtained with the robust controller and a nominal one are compared. Results illustrate the convenience of including robust strategies in designing control laws for an artificial pancreas (AP). "
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."
Model-based control design for H2 purity regulation in high-pressure alkaline electrolyzers
(2021-05) David, Martín Rafael; Bianchi, Fernando D.; Ocampo-Martínez, Carlos; Sánchez-Peña, Ricardo
"This paper proposes two control strategies that mitigate the cross contamination of H2 and O2 in a high-pressure alkaline electrolyzer, which consequently increases the supplied gases purity: one based on a decoupled PI scheme and the other based on optimal control tools. In order to reduce the diffusion of gases through the membrane, the controllers establish the opening of two outlet valves based on the pressure of the system and the difference in liquid level between both separation chambers. Therefore, two multiple input - multiple output controllers are designed here. For this purpose, a high-fidelity model previously developed was simplified in order to obtain a control-oriented model. The proposed controllers were evaluated in simulation using the high-fidelity nonlinear model in a wide operating range, which resulted in less than 1% impurity of gases."
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."
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.
Time-varying procedures for insulin-dependent diabetes mellitus control
(2011-03) Sánchez-Peña, Ricardo; Ghersin, Alejandro S.; Bianchi, Fernando D.
"This work considers the problem of automatically controlling the glucose level in insulin dependent diabetes mellitus (IDDM) patients. The objective is to include several important and practical issues in the design: model uncertainty, time variations, nonlinearities, measurement noise, actuator delay and saturation, and real time implementation. These are fundamental issues to be solved in a device implementing this control. Two time-varying control procedures have been proposed which take into consideration all of them: linear parameter varying (LPV) and unfalsiﬁed control (UC). The controllers are implemented with low-order dynamics that adapt continuously according to the glucose levels measured in real time in one case (LPV) and by controller switching based on the actual performance in the other case (UC). Both controllers have performed adequately under all these practical restrictions, and a discussion on pros and cons of each method is presented at the end."

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