Position Tracking Control of Robotic System with Time-varying Delay and Dead-zone

Abstract

This paper studies the position tracking control problem of nonlinear robotic system subject to time-varying state delay and input dead-zone. The input dead-zone and unknown external disturbance are regarded as the lumped disturbance and a sliding mode disturbance observer is designed. In order to ensure the stability of the robotic system with time-varying state delay, a position tracking controller based on auxiliary position tracking error functions is designed. Considering the estimated error of the sliding mode disturbance observer, a gain adaptive law is designed to further improve the position tracking accuracy of the system. The stability of the proposed controller is theoretically proved by Lyapunov-Krasovskii function method, and the effectiveness of the controller is verified by comparative simulations. The proposed control method can achieve stable and accurate position tracking of the robotic system with simultaneous time-varying state delay and input dead-zone.