Theoretical and experimental studies for a new disc-type ultrasonic stator

In this paper, a new disc-type ultrasonic motor is introduced. Its stator is a circular disc with a bonded PZT plate serving as a driver. The rotor is driven by a lateral elliptical motion occurring at the stator edge. An analytical formulation of the lateral elliptic motion based on the wave equations is derived to show the operation principles. The driving frequency, the force and the revolution speed induced from the lateral elliptic motion are obtained following the analytical derivation. The relationship between the new disc-type ultrasonic stator and its boundary condition is discussed. A laser vibrometer is used to verify the analytical model. The result proves that the stator with three non-equal-triangular fixed points (120/spl deg/-90/spl deg/-150/spl deg/) near the edge achieve the best performance.