Robust Fast Terminal SMC with Prescribed Performance for a Wearable Exoskeleton Robot

Abstract

This document proposes a robust fast terminal sliding mode control system with prescribed performance for an upper limb exoskeleton robot used for rehabilitation purposes. The controller is introduced to achieve highly accurate performance for trajectory tracking in the joint space under the effect of both internal uncertainties and external perturbations. The developed prescribed performance function plays the main role in converging the tracking error to a user-defined small gap rapidly. The expression of the conventional terminal sliding mode control system has been rewritten to meet the prescribed function effect. A stability analysis based on Lyapunov theory has been delivered to ensure that the system is stable. A simulation experiment on the 7-DoF ETS-MARSE robot and a comparison with conventional SMC have been conducted to prove the effectiveness and robustness of the proposed control scheme.