Novel fixed-time sliding mode control of lower limb rehabilitation exoskeleton robots
SUN Zhe
HUANG Fan-jie
ZHOU Yuan
CHEN Bo
ZHAO Qing-yu
WANG Hai
Abstract：In this paper,a novel fixed-time convergent sliding mode control method is proposed for the gait trajectory-tracking problem of lower limb rehabilitation exoskeleton robots.Firstly,the dynamic model of a lower limb rehabilitation exoskeleton robot is achieved through mechanism analysis.Then,a novel nonsingular fast terminal sliding surface is designed to achieve fixed-time convergence and effectively enhance the convergence rate.A new sliding mode control strategy for lower limb rehabilitation exoskeleton robots is designed based on this sliding surface,and the stability and global fixed-time convergence characteristics of the control system are proved by using the Lyapunov criterion.Finally,the proposed control method is experimentally validated via a lower limb rehabilitation exoskeleton robot experimental platform.The experimental results show that the control method proposed in this paper can achieve rapid convergence of lower limb exoskeleton trajectory tracking error,with the error converging to about 1°,strong robustness against wearers of different weights(61 kg and 80 kg)and different gait trajectories(with the period of 8 s and 6 s),and has a certain inhibitory effect on chattering phenomenon.
Keywords：lower limb rehabilitation exoskeletonsliding mode controlgait trajectory trackingfixed-time convergence
Publication Date：2026-02-28
Online Publishing Date：2026-04-08(First online date of this platform, not the publication date of the document)
Pages：11( 377-387 )