Survey of a contact model and characteristic analysis method for a travelling wave ultrasonic motor

The important research area associated with the Ultra-Sonic Motor (USM) is the contact problem between the stator and the rotor. Because the USM operates by the friction force between the rotor and the stator, the contact problem of the USM have to be taken into account to analyze the motor performance accurately. Consequently, various types of the analysis methods have been proposed based on a contact model which describes the complex nonlinear contact condition of the USM. In this paper, diverse types of contact analysis methods for a Travelling Wave Ultra-Sonic Motor (TWUSM) are clearly condensed and precisely examined. The governing equations for the analysis of the TWUSM performance are derived through a precise investigation of the relationship between the contact condition and the motor performance in this paper. Furthermore, the motor performance is analyzed using contact models and the calculated data are compared with the experimental results.