Backstepping controller design for electro-hydraulic servo system with sliding observer

Because an electro-hydraulic servo system is nonlinear, its parameters are difficult to measure and control accuracy is needed highly, a backstepping control method with sliding state observer is presented. In this strategy, state observer is designed by sliding method, velocity sensor and press sensor aren´t needed, and position sensor is needed only. To reducing chattering with sliding method, the saturation function is used to replace signal function. In order to deal with system´s uncertainty, controller is designed with backstepping method. The uniformly ultimately bounded (UUB) stabilities of all signals are proved by Lyapunov stability theorem. This method can guarantee the stabilization of the closed-loop systems. Finally, simulation results are presented to illustrate the effective and the applicability of the suggested method.