Operating principle and vibration characteristic of an I-shaped ultrasonic motor

An I-shaped ultrasonic motor using longitudinal vibrations is proposed, designed, and analyzed. The operating principle is discussed. The resonance frequencies of the three transducers are tuned to be close by modal analysis. Then, the vibration trajectories of the four tip ends of the two horizontal transducers are investigated by transient analysis. Oblique elliptical movements are generated on the four tip ends by the superimposing of the three longitudinal vibrations. The two upper driving feet will produce downward thrust forces while the two lower feet can push the runners upward. Intensive coupling bending vibrations are generated in the horizontal transducers under the horizontal mode of the proposed motor. The study results show that the coupling bending vibration of the horizontal transducer must be weakened for the realization of four feet synchronous driving. At present, the proposed design can be used as a bidirectional linear standing wave ultrasonic motor under the horizontal mode.