Velocity Control of Servo Systems Under Control Input Saturation and Disturbance Using Robust Discrete-Time Sliding Mode Control Method

This paper designed a new robust velocity control method for industrial servo systems. Exogenous disturbances and control input saturation are considered by using the discrete-time Sliding mode control with Decoupled disturbance compensator and Auxiliary state (SDA) method. The discrete-time SDA method preserves the original stability of the sliding mode dynamics as well as the stability of the disturbance estimation error dynamics under both control input saturation and disturbance. Due to these attributes, the discrete-time SDA method has been utilized in various control applications. In this paper, the discrete-time SDA method is newly designed for velocity control applications. Based on the error dynamics of the discrete-time SDA method, the gain of the auxiliary state is set to "1". This design provides the stability of velocity error, and there is nearly zero overshoot under control input saturation. Experiments are performed to demonstrate the performance of the designed control method.