Adaptive sliding mode control for a lower-limb exoskeleton rehabilitation robot

Abstract

This paper presents an adaptive sliding mode control (ASMC) method for wearable lower extremity exoskeleton. Since the dynamic control system of lower limb exoskeleton robot is non-linear, it is difficult to track the desired trajectory accurately. In this paper, an adaptive single-input single-output (SISO) system, whose adaptive law is designed based on the Lyapunov method, is applied to calculate the element of the control gain vector in a sliding mode controller. A simulating model was built, different control methods, like PID control, classical sliding mode control, and adaptive sliding mode control, have been tested on the prototype. The results show that ASMC has better performance in eliminating jitter and tracking trajectories than PID and classical sliding mode control.