Research on simulation of sliding mode variable structure control for the separating-mirror servo system based on S-function

For the separating-mirror servo system influenced by internal parameter changes and external non-linear friction, the sliding mode variable structure controller is designed. By exponential reaching law and saturation function combined method to reduce the chattering of the sliding mode variable structure controller. In Simulink simulation, S-function is used to realize the controller, the controlled object and the non-linear friction model. The simulation results show that the sliding mode variable structure controller possess good robustness for internal parameter changes and external disturbances of the separating-mirror servo system compared with the conventional PID controller. The control precision of the separating-mirror servo system is improved. The application of S-function simplifies the simulink simulation modeling of the complex system and advances the simulation speed.