Driving the Coiled Stator Ultrasonic Motor Using Traveling Wave Generated by Superimposing Two Standing Waves

In this paper, we describe experimental results of driving a coiled stator ultrasonic motor (CS-USM) using two transducers simultaneously. When the transducers are excited with a certain phase difference, the rotation direction is reversed. The CS-USM is a traveling-wave-type ultrasonic motor that uses a stator in a form of a helical coil. Owing to its simple structure, the motor can be made much smaller than conventional ultrasonic motors. For its practical use, the motor must be driven by transducers placed close to the driving section, and the direction of the rotation must be controlled.