Design of a cross-shaped piezoelectric motor with single driving foot

A cross-shaped piezoelectric motor with length of 43mm and diameter of 11 mm was proposed in this paper. Two third bending modes were used to generate ellipse trajectory at the driving foot located at the vibrator's center. Sixteen pieces of piezoelectric ceramic plates with sizes of 5mm×3mm×1mm were used to excite two third bending modes. Sine and cosine voltages with effective value of 100V at the frequency of 54.696 kHz were applied to the piezoelectric ceramic plates in right and left sides of the vibrator. Symmetrical structure of the motor solved the problem of mode frequency degeneracy. Two excitation methods were put forward to excite two third bending vibrations. And effectiveness of the two excitation methods was compared by the transient analysis with finite element method. Transient analysis results showed that motion trajectories of nodes on the driving feet were three-dimensional and that ellipse motion in the XOY plane was fit to drive the motor, and the new excitation method improves the vibration amplitude in the OX and OY by 2 times and 4 times, respectively compared with the vibration amplitude excited by the traditional excitation method.