Study on the vibration coupling of ultrasonic motor using longitudinal transducers

A linear ultrasonic motor using longitudinal vibration transducers with single foot was proposed, designed, fabricated and tested in a previous study. The longitudinal vibrations of two orthogonal bolt-clamped transducers are superimposed to produce elliptical movements on the driving foot. Firstly, the operating principle of the proposed motor is discussed. The longitudinal and bending vibrations of the transducers are gained by modal analysis. Then, the resonance frequencies and input impendence characteristics of the individual transducers and the motor are calculated respectively to gain the effect from the vibration coupling. The study results state that the vibration coupling between the transducers make their longitudinal resonance frequencies have small increases and the electromechanical coupling factor of the vertical transducer has an obvious decrease after it is linked with the horizontal one. As last, the coupling bending vibrations of the transducers are tested by using a scanning laser Doppler vibrometer.