A Design Method of Sliding Mode Controller for Servo-systems Subject to Actuator Saturation

摘要

This paper deals with compensation for windup phenomena due to actuator saturation in sliding mode control systems with integral action. It is shown that the actuator saturation causes windup phenomena similar to integrator windup, which might take place in linear control systems with integral action, even if the linear component of the control input does not include any integral action. This means it is not sufficient just to apply the existing anti-windup methods for the linear controllers to the sliding mode controllers. In other words, the nonlinear component of the control input should be reconsidered. Therefore a simple modification for the switching function is presented in order to reduce the nonlinear component of the input during saturation. It is shown that this modification makes it possible to keep the plant state close to the ideal sliding mode. Simulation and experimental results show the effectiveness of the proposed method.