Discrete-time integral sliding mode position control of H-type platform direct-drive servo system based on smooth saturation function

Abstract

The direct-drive servo system of H-type platform is easily affected by load disturbance and mechanical coupling. In this paper, a discrete-time integral sliding mode position control method based on smooth saturation function is proposed. First, the discrete-time mathematical model of direct-drive servo system with mechanical coupling characteristics is established with the position and speed of mover as state variables. Then, a discrete-time integral sliding mode position controller is designed to reduce the influence of external disturbance, and improve the tracking accuracy of the system. At the same time, in order to weaken the chattering caused by the sign function in the control law, a smooth saturation function is designed to replace the original sign function, and the advantages of the smooth saturation function are analyzed and proved. Finally, the simulation and experimental results show that the proposed method not only improves the position tracking accuracy of the system, weakens the chattering, but also enhances the robustness of the system to load disturbance.