title: Time-scaling based sliding mode control for Neuromuscular Electrical Stimulation under uncertain relative degrees.
abstract: This paper addresses the application of the sliding mode approach to control the arm movements by artificial recruitment of muscles using Neuromuscular Electrical Stimulation (NMES). Such a technique allows the activation of motor nerves using surface electrodes. The goal of the proposed control system is to move the upper limbs of subjects through electrical stimulation to achieve a desired elbow angular displacement. Since the human neuro-motor system has individual characteristics, being time-varying, nonlinear and subject to uncertainties, the use of advanced robust control schemes may represent a better solution than classical Proportional-Integral (PI) controllers and model-based approaches, being simpler than more sophisticated strategies using fuzzy logic or neural networks usually applied in this control problem. The objective is the introduction of a new time-scaling base sliding mode control (SMC) strategy for NMES and its experimental evaluation. The main qualitative advantages of the proposed controller via time-scaling procedure are its independence of the knowledge of the plant relative degree and the design/tuning simplicity. The developed sliding mode strategy allows for chattering alleviation due to the impact of the integrator in smoothing the control signal. In addition, no differentiator is applied to construct the sliding surface. The stability analysis of the closed-loop system is also carried out by using singular perturbation methods. Experimental results are conducted with healthy volunteers as well as stroke patients. Quantitative results show a reduction of 45% in terms of root mean square (RMS) error (from 5.9° to [Formula: see text] ) in comparison with PI control scheme, which is similar to that obtained in the literature.
authors.affiliation: Department of Electronics and Telecommunication Engineering, State University of Rio de Janeiro (UERJ), Rio de Janeiro, RJ 20550-900, Brazil. Electronic address: tiagoroux@uerj.br.
authors.forename: Tiago Roux
authors.initials: TR
authors.lastname: Oliveira
authors.affiliation: Biomedical Engineering Program, Federal University of Rio de Janeiro (COPPE/UFRJ), P.O. Box 68510, Rio de Janeiro, RJ 21945-970, Brazil.
authors.forename: Luiz Rennó
authors.initials: LR
authors.lastname: Costa
authors.affiliation: Biomedical Engineering Program, Federal University of Rio de Janeiro (COPPE/UFRJ), P.O. Box 68510, Rio de Janeiro, RJ 21945-970, Brazil.
authors.forename: João Marcos Yamasaki
authors.initials: JMY
authors.lastname: Catunda
authors.affiliation: Biomedical Engineering Program, Federal University of Rio de Janeiro (COPPE/UFRJ), P.O. Box 68510, Rio de Janeiro, RJ 21945-970, Brazil.
authors.forename: Alexandre Visintainer
authors.initials: AV
authors.lastname: Pino
authors.affiliation: Department of Electronics and Telecommunication Engineering, State University of Rio de Janeiro (UERJ), Rio de Janeiro, RJ 20550-900, Brazil.
authors.forename: William
authors.initials: W
authors.lastname: Barbosa
authors.affiliation: Biomedical Engineering Program, Federal University of Rio de Janeiro (COPPE/UFRJ), P.O. Box 68510, Rio de Janeiro, RJ 21945-970, Brazil.
authors.forename: Márcio Nogueira de
authors.initials: MN
authors.lastname: Souza
mesh_terms: D001132:Arm / Q000502:physiology* / Q000503:physiopathology; D004558:Electric Stimulation / Q000295:instrumentation / Q000379:methods*; D064368:Healthy Volunteers; D006801:Humans; D009068:Movement; D009132:Muscles / Q000502:physiology* / Q000503:physiopathology; D009424:Nervous System Physiological Phenomena; D020521:Stroke / Q000503:physiopathology; D013997:Time Factors; D035501:Uncertainty
keywords: Neuromuscular electrical stimulation; Output feedback; Singular perturbation; Sliding mode control; Stroke patients; Trajectory tracking; Uncertain systems