Passive torque servo system based on proportional-resonant control

When passive torque servo system is used to simulate load torque, the load torque acted on actuator contains high disturbance torque due to the movement of actuator. In order to realize precise load torque simulation, a novel electric passive torque servo system was proposed, in which proportional resonant controller was added to the outer control loop. By embedding proportional resonant controller with the same frequency, sinusoidal torque signal was tracked with zero steady-state error, and disturbance torque caused by periodic motion of loaded actuator was restrained effectively; combining with root locus and frequency domain design method, unit proportional resonant controller was put forward to design parameters of controller; moreover, speed feed-forward compensation method was used to reduce impact of disturbance torque acted on system and torque sensor in the beginning. Simulation and experimental results show that 20Hz sinusoidal load simulation can be tracked with zero steady-state error and periodic load simulation can be tracked with high precision under dynamic load mode.