Development of piezoelectric actuators with rotational and translational motions (TR motor)

We have developed piezoelectric actuators having a single stator with rotational and translational motions (TR motor). Piezoelectric actuators use mechanical vibration as the principle of drive. The stator has been fabricated as a rectangular metallic solid with a through-hole. The surface of the inner circle of the hole generates vibration modes, transferring the energy to shaft, when voltages at each resonant frequency are applied. In this paper, the driving principle of the TR motor was clarified using finite element method (FEM). Modal analysis yielded the modes shapes and the natural frequency, and then the figure of the stator was designed. Dynamic analysis of the inner surface generated elliptical motions and indicated the motions of the TR motor. We propose two method of the vibration analysis using FEM. First we conducted the dynamic analysis on the assumption that excitation force was directly applied to the stator. Secondly, we conducted the piezoelectric analysis using the FEM software ANSYS. Piezoelectric analysis simulates the behavior of piezoelectric elements when driving voltage is applied to them.