Multiple sliding mode adaptive control of the closed electro-hydraulic proportional system

According to the nonlinear closed electro-hydraulic proportional system, a multiple sliding mode adaptive control method is proposed. Recursive technique is used to simplify the control problem of higher-order system. A robust adaptation scheme was used to reduce the tracking error resulted from system uncertainties . Firstly, the recursive technique and state feedback precise linearization scheme is used to obtain the design method of multiple sliding mode controller of a given system. Then, the system-parameter-update law and robust adaptive controller of an uncertain system are presented based on Lyapunov scheme. The proposed method is applied to speed tracking control of an electro-hydraulic proportional system. Simulation results indicate that the control approach is robust and improves tracking accuracy considerably.