Nonlinear Adaptive Robust Control of Valve-Controlled Symmetrical Cylinder System

A nonlinear adaptive robust control method based on a differentiable LuGre friction model is proposed for the problems of uncertain parameters, nonlinear friction and time-varying disturbances in valve-controlled symmetrical cylinder system. The proposed method can effectively compensate the uncertain nonlinear characteristics and external disturbances in the system by combining adaptive robust control with state and disturbance observations, as well as sliding mode differential technique. The global stability and boundedness of the proposed control method are proven by applying the Lyapunov theory. The simulation results show that this control method can deal with the problems of the uncertain nonlinearities and disturbances within the system. The proposed control method also presents excellent dynamic performance and robustness.