DESIGN OF ANGULAR POSITION CONTROL SYSTEM FOR FLUID DRIVE MOTOR

This paper describes the angular position control system for a fluid drive motor. The fluid drive motor has a similar driving principle with the fluid drive spindle that is designed for the spindle of precision machine tools. The fluid drive motor is driven by the water or oil flow power. In the present paper, the rotational speed controller is first discussed. In order to reduce the influence of external load torque on the rotational speed, a conventional disturbance observer is combined with the rotational speed control system. The angular position control system, which possesses the rotational speed controller as a minor feedback loop, is then discussed. Performances of the designed angular position control system are studied via simulations and experiments. It is verified that the influence of the external load torque on the rotational speed is successfully compensated. The angular position control system is tested through simulations and experiments, as well. Experimental result shows the designed angular position control system suppresses steady state positioning error less than 0.02 degree, even if external constant load torque acts on the motor.