A novel ring type ultrasonic motor with multiple wavenumbers: Design, fabrication and characterization

A novel ring type traveling wave ultrasonic motor (USM) with multiple wavenumbers has been designed, fabricated and characterized. This multiple wavenumber operation is realized by means of a new electrode configuration of the piezoelectric element. The experimental and numerical performance results for the multiple wavenumbers show that USM with multiple wavenumbers significantly outperform the single wavenumber motor as regards the range of speed and torque output. This novel implementation of the traveling wave motor also offers extra control for stable operation of USM. The performances of the control variables, the wavenumber and the amplitude, are compared to show their advantages and disadvantages. The speed control range for the wavenumber is larger than that for amplitude control; wavenumber control has better stability at low speed while amplitude control can work continuously with less wear. Hybrid control using both methods may result in better performance of USM. © 2009 IOP Publishing Ltd.