An optimum design for the hybrid transducer ultrasonic motor in symmetrical structure

This study is focused on the optimization of the longitudinal vibration system for a hybrid transducer ultrasonic motor in order to obtain effective friction control at the rotor/stator contacting interface. The basis of our design is that the piezoelectric elements for the longitudinal vibration are located just at the contacting interface, and the interface is tuned to the nodal plane of the longitudinal vibration mode. A prototype motor 20 mm in diameter achieved the maximum torque of 8 kgf/spl middot/cm, which was higher than that of other previously reported motors.