Effect of Positive Angular Velocity Feedback on Torque Control of Hydraulic Actuator

Output torque/force of a hydraulic actuator is generally affected by its driving speed. This may cause deterioration of the control accuracy of the system in which the plant is controlled through the driving torque/force control of the actuator. This study proposes a positive angular velocity feedback for compensation of the effect of the driving speed on the driving torque control of a rotary hydraulic actuator. The compensation scheme is experimentally applied to motion control of a one-link hydraulic robot which is controlled by means of the computed torque method. The experiments show that the compensation scheme is effective in isolating the driving torque of the actuator from its driving speed and slightly improves the tracking accuracy of the motion control.