Slope start phenomenon of Ultrasonic Motor (2nd Report: Theoretical analysis)

Abstract

Strong holding torque is one of the advantages of ultrasonic motors. However, the previous report shows the rotors turn backward at the start-up of the stator vibration if large load torque is applied. This slope start phenomenon prevents the utilization of the holding torque of the ultrasonic motors in some applications, such as robot end effectors. In this research, the rotation response at start-up was simulated with the equivalent circuit model and the friction contact model. The simulation shows that the backward rotation can be mitigated by accelerating the start-up time of stator vibration.