High order longitudinal and bending hybrid ultrasonic motor with new excitation

A high order longitudinal and bending hybrid ultrasonic motor with new excitation is proposed in this study. In the new type motor, the locations of two sets of piezoelectric ceramics are the loops of bending vibration mode. By applying two alternating voltages to the ceramics, the second longitudinal and the fifth bending vibrations will be superimposed, that make the points of the driving feet to move elliptically. The finite element method is adopted to realise two phase vibration frequency degeneration. The vibration locus of the driving feet is obtained by means of transient analysis; elliptical trajectories are observed, which verify the driving principle of the new type motor. The impedance characteristics, the vibration modes and mechanical ability of the new motor are verified by prototype tests. When the excitation voltage is 450 V^p-p, the maximum noload speed and the maximum output force of the prototype are 439 mm s^-1 and 37 N respectively.