Flatness tracking control scheme of rehabilitation exoskeleton robot with dynamic uncertainties

Abstract

Artificial limbs are new robotic devices created to help stroke victims in the rehabilitation process. In this article, we focus our work on applying passive, active or assistive control strategies to provide a physical assistance and rehabilitation by a 7-degree-of-freedom exoskeleton robot with nonlinear uncertain dynamics and unknown bounded external disturbances due to the robot user’s physiological characteristics. The flatness controller combined with time-delay estimation is designed for the 7-degree-of-freedom exoskeleton robot called ETS-MARSE (Ecole de Technologie Supérieure—Motion Assistive Robotic-exoskeleton for Superior Extremity) in order to ensure a passive rehabilitation exercises with a high level of tracking accuracy and robustness against the uncertainty constraints. The stability analysis of such systems is proven using the Lyapunov–Krasovskii functional theory. This approach is illustrated by experimental results with healthy human to highlight the efficiency of the suggested controller scheme.

Distributed adaptive controller for the cooperative control of networked parametric strict feedback systems

“…Theorem 1. Consider a network composed of N agents with dynamic equation (1), the control law equation (16), and parameter estimators' updating laws equations (7), ( 8), (12), and (17). Under Assumptions 1 to 3 and the communication digraph has a spanning tree, it is ensured that: (1) Practical output synchronization of the multiagent system is realized; (2) Other signals in the closed-loop system are bounded.…”

“…[5][6][7] With the development of system identification and control method, nonlinear systems with uncertainties have been the hotspot of cooperative control, for example modeling uncertainty 8 and input saturation 9 are considered in leader-follower multiagent system, tracking control of nonholonomic aircraft in unknown flow field, 10 formation control in multiagent systems with nonmatching disturbances, 11 stabilization problem of multiagent systems subject to unmatched modeling uncertainties, 12 antidisturbance control problems under hybrid switching, 13 output regulation for networked parabolic systems with varying parameters, 14 and consensus tracking control of switching systems subject to external disturbancse 15 . In addition, in practical applications, the study of systems affected by uncertainty is also crucial, such as the study of tracking control of rehabilitation exoskeleton robot with dynamic uncertainty, 16 and the study of vehicle queue control with unknown parameters and time delays. 17 Due to its universality, cooperative control of multiple parametric strict feedback (PSF) systems has been widely investigated.…”