Contact analysis and modeling of a linear ultrasonic motor with a threaded output shaft

This paper presents a contact analysis and a mathematical model for a linear ultrasonic motor with a threaded output shaft. The motor utilizes an out-of-plane traveling wave and an in-plane traveling wave to drive the output shaft. Two kinds of contacts are analyzed and modeled respectively. A numerical model is developed to predict the performance and behavior of the motor, including the no-load speed, the maximum driving force, the maximum output power, and the effects of the thread pitch, the dynamic friction coefficient, the mean thread radius on motor performance. A prototype motor is fabricated and experimental testing is performed to compare the experimental results with the predictions from models. The model developed here can be used as a design tool for designing and optimizing the linear ultrasonic motor with a threaded output shaft.