A study on driving characteristics of the cross type ultrasonic rotary motor

Ultrasonic rotary motor which has cross type stator was studied. The stator was consists of hollowed cross type metal which has four piezoelectric ceramics on the ends of cross bars. When two harmonic voltages which have 90∘ phase difference were applied to ceramics, the symmetric and anti-symmetric displacements were generated at the inside tips to make the elliptical motion. The finite element analysis was used for optimizing the dimension and displacement of the stator. And the analyzed results were compared with the experimental results of the motor. As results, the speed of motors could be controlled by changing the applied voltages, and the rotational direction of motors could be changed by the phase change. Speed and torque of the motors were increased by increasing the width of cross bars, and the torque and displacement was increased by increasing angle of the cross bars.