Experimental verification of elliptical motion model in traveling wave ultrasonic motors

We propose a model of a traveling wave ultrasonic motor that includes the elliptical motion amplitudes of the stator and verify this model experimentally using a high-speed camera with a high-power lens (i.e., a high-speed microscope). This approach makes it easy to estimate the motor characteristics, such as the rotational speed and torque. In this paper, we build a mechanical model of the stator and rotor that incorporates the elliptical motion amplitudes. The elliptical motion of a few microns at ultrasonic frequencies is captured and measured by the high-speed microscope. When modeling parameters are determined from the observed vibration amplitudes, the model can predict the motor characteristics. We study how the observed elliptical motion is related to the motor output by varying the frequency of applied voltages, and verify the proposed model by comparison with the experimental results.