Adaptive Terminal Sliding Mode Control of Uncertain Electro-Hydraulic Position Servo Systems

Abstract

To solve the position tracking control problem of nonlinear and uncertain electrohydraulic servo systems, an adaptive terminal sliding mode control method based on the backstepping method was proposed. This method combines the adaptive control with the terminal sliding mode method. On the one hand, the proposed adaptive control law can effectively estimate and compensate the uncertain parameters of the electro-hydraulic servo system on line, on the other hand, with the variable coefficient reaching law obtained through introduction of the error attractor into the sliding mode reaching law, the designed terminal sliding mode control law can not only eliminate the non-singular term in the ordinary terminal sliding mode control law, but also greatly reduce the chattering of the sliding mode surface. Finally, according to the Lyapunov stability theory, the finite time stability of the position tracking error was proved strictly. The proposed method was compared with the integral backstepping sliding mode control and the linear sliding mode control. The simulation results show that, the proposed method has good robustness and tracking accuracy in position tracking control of electro-hydraulic servo systems.