Rotary piezoelectric motor using a rectangular vibrator of four actuators

Abstract

Piezoelectric rotary motors have become the standard motor for rotational motorization. However, due to its complex structure and operational mechanism, its cost is considerably high. To reduce the complexity and cost of piezoelectric rotary motors, we developed a new type of motor driven by traveling waves. It is constructed of a rectangular stainlesssteel plate and four piezoelectric actuators. To generate a rotational traveling wave on a rectangular plate, two higherorder bending modes are stimulated to generate rotational traveling waves propagating in a diamond-shaped trajectory. The dimension of the stainless-steel plate and four piezoelectric PZT plates attached to its surface. The boundary conditions are chosen to be simply supported in the x-direction and free-edge in the y-direction, and an analytical model is derived for analyzing its vibration profile. To stimulate the rotational traveling waves, the Φ34 and Φ43 bending modes are chosen. The dimension of the stainless-steel plate was designed, and the resonant frequencies are close to each other at 2.733kHz and 2.781kHz. Using this design, both bending modes are simultaneously excited with a single driving frequency at 2.757kHz. The combined Φ34 and Φ43 bending modes became a steady rotary traveling wave, and it can be used to drive a rotary starter. It is also found that the vibration performance could be optimized by modulating the phase difference and voltage ratio between the Φ34 and Φ43 bending modes. Finally, the driving method of this piezoelectric rotary motor is experimentally verified and compared with the analytical model.