Piezoelectric motor operated both in resonance and DC modes

Inhalt:
Advanced precise positioning and control of piezoelectric motors in a wide range of velocities need both dynamic and static excitations for achieving various purposes like compensation of hysteresis type nonlinearities and fast step-settle movement. This paper presents a new type of piezoelectric motor; in which a hard type piezoelectric bulk ceramic is modified further for getting static deflections in nm range by applying a DC voltage and ultrasonic oscillatory continuous movements to obtain high speed at resonance mode drive. Static movement is required for the drift and hysteresis corrections when the piezoelectric motor is at a standstill or in a positioning phase. The actuator structure presented here with rectangular finger electrodes enables both resonant and static operation of piezoelectric motor and is designed by using finite element analysis and verified by prototypes. Geometric parameters like thickness and aspect ratio of piezoelectric ceramic plate, and length, width and spacing of finger electrodes are optimized to achieve higher static movement per unit applied electric field. Proposed piezoelectric motor prototype integrated in a precision stage can deflect statically up to 100 nm per ± 200 V DC voltage.