Mixed sensitivity H∞ controller design for variable-speed pump-controlled motor system

This paper focuses on constant speed control of variable speed pump controlled motor system. The nonlinear model of pump controlled motor system is derived and its parametric perturbations are taken into consideration. To decouple pump speed variation from H_∞ controller, a closed loop flow rate controller of hydraulic pump based on Bang-Bang control and low pass filter is proposed. Mixed sensitivity H_∞ controller with load torque observer is achieved to reduce maximum speed error and settling time of hydraulic motor. Simulation results show that the proposed control scheme is superior to PID controller.