A Crossbeam Linear Ultrasonic Motor using Bending Vibrations

A crossbeam linear ultrasonic motor with length of 38 mm and diameter of 11 mm is proposed in this paper. Eight pieces of PZT ceramic plates with size of 10mmx3mmx1mm are glued to metal base to form stator. PZT ceramic plates are divided into two groups and excited by sine and cosine voltages respectively. The proposed motor generates elliptical movements at two driving feet by superimposing of two first bending vibration modes. The two first bending vibration modes have same resonance frequency as the symmetrical structure of the stator, which avoids modal degeneration. Working principle of the motor is introduced, and vibration modal and transient analyses by finite element method are developed in this paper. Sine and cosine voltages with effective value of 100 V at frequencies of 35.596 kHz are applied to the stator model. Transient analysis results show that motion trajectories of particles on driving feet are three-dimensional ellipse. The particles' maximum displacements in OX, OY and OZ directions are about 3.0 mu m, 3.0 mu m and 0.5 mu m, respectively. Amplitude of OZ direction is about 16.7% of OX and OY directions, which demonstrates that elliptical motion in the XOY plane is fit to drive the rotor.