Using a Laser Doppler Vibrometer to Test a New Cone-shell-shaped Rotating Traveling Wave Ultrasonic Motor
J-L. Yang, Y. Chen, Y-D. Zhao and J-B. Yang
A new cone-shell-shaped rotating traveling wave ultrasonic motor is proposed, designed, fabricated and experimentally tested. The cone-shell rotating ultrasonic motor vibrator proposed in this paper is cone-shaped. The third-order bending vibration mode of the cone-shell vibrator can couple in-plane bending vibration and out-of-plane bending vibration. The traveling wave drive of the new oscillator structure is realized. The cone-shell vibrator can excite two same-frequency orthogonal third-order bending modes under the excitation of two sets of trapezoidal piezoelectric ceramic sheets. Elliptical movement of the vibrator is formed on the inner wall of cone which can drive the rotor to rotate. The structural dimensions, third-order bending modes and frequencies of the oscillator were determined by using finite element analysis software. Then a prototype was fabricated. The resonant frequency and vibration modal of the third-order bending mode of the cone-shell oscillator was effectively measured using a laser Doppler vibrometer. An experimental system was then established to test the mechanical output characteristics. When the peak-to-peak excitation voltage was 240 V and the resonant frequency was 27.53 kHz, the maximum speed of the ultrasonic motor at no load was 85.8 rpm and the blocking torque was 441 mN·mm.
Keywords: Laser Doppler vibrometer, ultrasonic motor, conical shell, rotating traveling wave, bending vibration, tapered contact