Abstract
This paper deals with the proposal of an electric-pneumatic hybrid drive system composed of an AC servomotor and a pneumatic cylinder type actuator, and its control methods. The rotational movement of the AC servomotor is transformed into the linear movement through a ball screw that is placed in the piston, and this hybrid drive system can be operated in the direction of gravitational force. Three control methods such as a pressure compensated control, a torque control and a hybrid control that combines both control methods are proposed from the view point of the reduction of the driving torque of the AC servomotor. The basic characteristics of the hybrid drive system are investigated by the experiment relating to the three control methods when the inertial mass moves vertically upwards and downwards during one cycle. Each control method is effective in reducing the driving torque of the AC servomotor and the views on the reduction of the driving torque of the AC servomotor in each control method are described.
