The active disturbance rejection control with a load torque observer for secondary regulation hydraulic speed system

This paper focuses on the speed control of the hydraulic secondary regulation system, which has a wide application prospect in hydraulic drive due to its high system efficiency, fast dynamic response and energy recovery capability. To obtain its robust speed control under the conditions of load disturbances and system parameters variations, an active disturbance rejection controller in conjunction with a load torque observer is proposed. The active disturbance rejection control doesn´t depend on the accurate system model and is inherently robust against plant variations. The load torque observer is used to estimate load torque disturbances and the estimation is used as a feed-forward compensation in the inner loop. The simulation results show that the combination of outer loop active disturbance rejection controller and inner loop load torque observer can significantly improve the static and dynamic performance of the speed system. Compared with the conventional PID control or using a single control approach, the proposed control approach achieves a fast and robust response without overshoot and has a strong anti-disturbance ability, even in the case of large load torque disturbances and variations in system parameters.