Modelling of the Linear Ultrasonic Motor using an Elliptical Shape Stator

A prototype of the linear ultrasonic motor using an elliptical shape stator was fabricated for analyzing the fundamental characteristics of the elliptical motor. In addition, a dynamic model of the motor was established in order to raise the understanding and improve the performance of the motor. In the ultrasonic motor, the elliptical stator is composed by two multilayer piezoelectric actuators clamped in an elliptical elastic body. Two orthogonal mechanical vibration modes of the stator can be excited to generate elliptical motion on the stator surface. By pressing the stator against a slider, friction forces between the stator and the slider occur, and the slider can be driven by the stator. To simulate the dynamic behaviour of the motor, the model is divided into three coupled subsystems: the stator, the contact mechanism, and the slider. The simulations including transient and steady state responses of the motor are performed by the Simulink and the results are validated by experiments. It is shown that experimental results are in good agreement with simulation results