Design and evaluation of a novel light arc-shaped ultrasonic motor

In order to achieve the application of ultra-sonic motors in small pan/tilt/zoom (PTZ), this study designed a light arc-shaped ultrasonic motor where the first-order longitudinal vibration mode and the second-order bending vibration mode were superimposed in the stator plane, in order to drive the rotation of the rotor. The stator was fabricated by phosphorous bronze and piezoelectric ceramic. ANSYS was used to simulate the motor performance in order to optimize its size and determine its operating mode. The motion trail of the end surface of the driving feet was also simulated. The frequency and amplitude of the motor prototype were measured using a three-dimensional (3D) laser vibration meter. The results, which were in good agreement with the simulation results, demonstrated that the prototype exhibited favorable vibration characteristics. The mechanical characteristics of the prototype were also tested. At an operating frequency of 126.5 kHz and an excitation signal of 350Vpp, the maximum rotating speed of the motor reached up to 230 rpm. Finally, the output torque of the motor configurations with single-stator and double-stator were proposed respectively was investigated. The output torque of the motor under the single-stator configuration reached up to 2.6×10-2 N·m, The double-stator which was 1.5 times greater than that under of single stator configuration. Conclusively, the designed motor is characterized by its light weight, high torque, and favorable output performances.