Abstract: Aiming at high speed sampling control systems with internal parameter perturbation and external disturbance,a novel Delta operator reaching law method,called S-type variable rate reaching law,was concerned based on sigmoid function,and a soft switching control for uncertain Delta operator systems was proposed based on sliding mode.Soft switching controller for continuous time systems and discrete-time systems can be unified into those of Delta operator systems via the principle of Delta operator sampling.The closed loop-string high speed sampling soft switching controller design based on sliding mode via Delta operator S-variable rate reaching law can reach the scope of the switching plane in limited moment,and reduce system flutter effectively.The simulation results demonstrate that the stability and process steady of the proposed controller are better than those of conventional exponential reaching law method,and the controller has a good completely robustness in entire dynamic process.

Key words: Sliding mode control,Soft switching control,Sigmoid function,Reaching law,Delta operator,Completely robustness