Fuzzy adaptive PID fast terminal sliding mode controller for a redundant manipulator

Abstract

Abstract In this study, a fuzzy adaptive PID fast terminal sliding mode controller has been proposed for a redundant manipulator system with a variable load. The method realizes an accurate tracking of the trajectory at the end effector of the manipulator and improves its robustness toward model uncertainty and external disturbance when controlling the position of the redundant manipulator. By using the advantages of the PID and the fast terminal sliding mode control, the convergence speed of the control algorithm has been improved, and its steady-state error has been reduced. Also, integration of the continuous approximation law has been used to eliminate the real-time chattering during the control process without affecting the robustness of the system. A fuzzy adaptive control law has been designed in order to estimate the error of the dynamic system and the upper bound of the disturbance on the external load. Further, the variable switching gain makes the control system achieve better performance in different external environments. Finally, the stability of the controller has been proved by the Lyapunov theory, and the effectiveness and superiority of the control method has been verified by using the simulation and experimental platform for a seven-degrees-of-freedom redundant robot manipulator.