Showing papers by "Hector Rios published in 2021"

Velocity Control of an Omnidirectional Wheeled Mobile Robot Using Computed Voltage Control with Visual Feedback: Experimental Results

Abstract: In this paper, we propose a novel computed voltage based control law for an omnidirectional wheeled mobile robot equipped with four mecanum wheels. First, the dynamical model for the mechanical part is originally introduced by means of the Euler-Lagrange formulation. The motion constraints are added to the dynamic model using the Lagrange multipliers. Then, the dynamic model is completed by incorporating the dynamics of the actuators. Therefore, the dynamical model input signals are the armature voltage of the motors. The control law requires only the feedback of position and velocity of the whole robot, unlike most controllers in the literature that also need wheel speed feedback. The position and velocity are obtained by means of a multicam vision system, so measurements from motor encoders are not needed. A high-order sliding modes differentiator is included to estimate linear and angular velocities in a finite time. A stability proof is presented by means of the direct Lyapunov method, and furthermore, an analysis about parametric uncertainties in the mechanical parameters is introduced. The experimental results validate the theoretical proposal and show the good performance of the approach.

Adaptive estimation for uncertain nonlinear systems with measurement noise: A sliding‐mode observer approach

Abstract: This paper deals with the problem of adaptive estimation, i.e. the simultaneous estimation of the state and time-varying parameters, in the presence of measurement noise and state disturbances, for a class of uncertain nonlinear systems. An adap-tive observer is proposed based on a nonlinear time-varying parameter identification algorithm and a sliding-mode observer. The nonlinear time-varying parameter identification algorithm provides a fixed-time rate of convergence, to a neighborhood of the origin, while the sliding-mode observer ensures ultimate boundedness for the state estimation error attenuating the effects of the external disturbances. Linear matrix inequalities are provided for the synthesis of the adaptive observer while the convergence proofs are given based on the Lyapunov and Input-to-State Stability theory. Finally, some simulation results show the feasibility of the proposed approach.

Continuous Sliding-Mode Output-Feedback Control for Stabilization of a Class of Underactuated Systems

Abstract: This paper presents a robust output-feedback control scheme for the stabilization of a class of non-linear underactuated mechanical systems in presence of coupled disturbances. The scheme is based on the so-called coupled sliding-mode control, i.e., no transformation into the normal form is required. The proposed output approach is composed of a Super-Twisting Controller and a High-Order Sliding-Mode Observer that robustly stabilize the origin of the system asymptotically. All of the results are proven by Lyapunov approaches. The proposed approach is validated by means of simulations and experimental results on a 4 degrees of freedom (DOF) underactuated crane.

Output-Feedback Sliding-Mode Controller for Blood Glucose Regulation in Critically Ill Patients Affected by Type 1 Diabetes

Abstract: In this brief, an output feedback continuous twisting algorithm is applied to solve the problem of glucose regulation in critically ill patients affected with type 1 diabetes mellitus. The proposed approach copes with disturbances coming from intrapatient and interpatient variability and does not need meal announcements. The blood glucose measurement and insulin infusion are via intravenous. The proposed algorithm regulates blood glucose and keeps it in the normoglycemia range, i.e., 70–180 mg/dl without nursing intervention. Therefore, the workload at the intensive care unit is alleviated. Besides, we provide a criterion to set the output feedback continuous twisting algorithm gains, which may be used for individualizing the insulin therapy. The approach is validated in the Universities of Virginia and Padua (UVA/Padua) metabolic simulator for ten in silico adult patients with unannounced meal intake. The results show excellent performance as well as minimal risk of hyperglycemic and hypoglycemic events. In addition, an open-loop study case is presented to evidence the advantages of output feedback continuous twisting algorithm over a traditional brief-based protocol in terms of nurse workload mitigation.

A Robust Control solution for Glycaemia Regulation of Type-1 Diabetes Mellitus

Abstract: The paper addresses the development of an artificial pancreas for the treatment of Type 1 Diabetes Mellitus, and more precisely the design of a control law for insulin delivery. As opposed to current existing solutions, the proposed approach is patient-independent, so it tackles the variability of the patients. Robust margins and worst-case performance are also established by means of the H∞/μ-analysis theory. The proposed solution is evaluated through the high-fidelity UVA/Padova simulator accepted by the US Food and Drug Administration as a substitute for pre-clinical testing of newtreatment strategies

Corrections to “Output-Feedback Sliding-Mode Controller for Blood Glucose Regulation in Critically Ill Patients Affected by Type 1 Diabetes”

Abstract: In the above article [1] , the authors would like to correct an error in the author byline. The correct order of author names is Roberto Franco, Alejandra Ferreira de Loza, Hector Rios, Louis Cassany, David Gucik-Derigny, Jerome Cieslak, Loic Olcomendy, and David Henry.