Design and experiment of a frame structure traveling wave ultrasonic motor

This paper presents an in-plane bending vibratory traveling wave rotary ultrasonic motor with a novel frame structure. The stator consists of an outer square frame and an inner circular frame connected by four short beams. The square frame can effectively excite the in-plane composite bending vibration. Meanwhile, the circular frame can excite the third-order in-plane bending vibration under the corresponding excitation. One rotor is driven by the square frame, and the other rotor is driven by the circular frame. It enhances the output characteristics of the micro traveling wave rotary ultrasonic motor. Structural design and simulation of the stator were conducted using finite element analysis software. A principle prototype was designed and manufactured according to the stator structure, and the stator vibration characteristics and the output performance of the prototype were tested. Comparisons were made between the output performance of the square frame and the circular frame within the stator. Experimental findings revealed that when an excitation signal of 20.825 kHz frequency and 300 V voltage was applied to the stator, the motor achieved a peak output torque of 0.84 N mm and a maximum no-load speed of 207 rpm.