Research on velocity fluctuation characteristics of traveling wave ultrasonic motor

Ultrasonic motor (USM) combines piezoelectric actuator with friction drive, and there is a non-negligible speed fluctuation. The pulsation of the rotating speed affects the stability and accuracy of the ultrasonic motor. In order to describe the inherent characteristics of speed fluctuation characteristics, this paper first analyses the error source of the eccentric inclination of the shaft relative to the stator, and tests the rotor speed under different parameters in a comprehensive experimental device driven by multiple parameters. Finally, of the speed results are analysed in time domain and frequency domain. The experimental results show that due to the axial error caused by machining, the pressure and velocity on both sides of the motor shaft are obviously unbalanced, and the polar coordinates of the speed fluctuation under different parameters have similar radiation, which proves the relationship between the speed fluctuation and the rotor angle.