A new design scheme for discrete-time variable structure control systems

The design scheme of variable structure control for discrete-time systems is considered. Due to the shortcoming of discrete exponential reaching law which can not push the system state approach to zero but induce oscillation, a new discrete reaching law is presented to improve the reaching process of discrete exponential reaching law via using saturation function to replace sign function. The discrete-time variable structure control system designed by this reaching law can not only weaken the chattering and push the system state approach to zero gradually, but also keep the basic property of quasi-sliding mode which can cross the switching surface step by step. This method improves the reaching process and enhances the control quality of the discrete-time variable structure control system. The simulation results validate the feasibility and reasonability of this method.