Ultrasonic stepping motor using spatially shifted standing vibrations

This paper proposes a novel configuration of ultrasonic stepping motor. It is based on the simple phenomena that an object on a vibrating body moves to the nodal position of the vibration mode and rests there. The use of standing flexural vibrations of a ring simplifies both the structure of the motor itself and the driving circuit. To move the nodal point, several standing modes spatially shifted with respect to each other are excited one after another by switching the driving position on the stator ring at the timing of stepping clock. In this paper, a 60-step stepping motor is designed and fabricated for trial, where an optimum combination of the order of the mode used and the number of the spatial phase shifts is discussed. The basic characteristics of the prototype motor is also studied experimentally.