Reduced‐Order ESO‐Based Fixed‐Time Sliding Mode Control for Robotic Manipulator With Prescribed Performance Constraints

ABSTRACT In this paper, a fixed‐time sliding mode control is studied for a robotic manipulator with prescribed performance constraints and input saturation. Specifically, the proposed scheme uses RESO to estimate the lumped disturbances, including modeling errors and external disturbances. The variable‐prescribed performance function (VPPF) and corresponding state transformation are proposed to solve the singularity problem in the presence of saturation. Then, based on VPPF, a fixed‐time sliding mode controller (PSMC) is developed to improve the fastness and robustness of the system. By means of the proposed control scheme, the fixed‐time stability of the entire closed‐loop system is demonstrated by the Lyapunov theory. Comparative experiments on robot manipulators are performed to illustrate the effectiveness and superiority of the proposed approach. The RMSE value with the proposed controller decreases by 90.86% compared to the conventional controller.