Contact modeling and performance evaluation of ring type traveling wave ultrasonic motors considering stator teeth.

A contact model of ring type traveling wave ultrasonic motors is proposed in this paper in order to investigate the dynamic contact and friction drive mechanism between the stator and rotor. Differing from previous contact models of ring type traveling wave ultrasonic motors, the Dahl friction model is adopted and the stator teeth are taken into account in the proposed model. The normal stress, the tangential stress, and the torque-speed characteristics of the motor are evaluated in detail based on the proposed model. Finally, the torque-speed values of the prototype motor are measured and compared with the calculation ones. The results show that the calculation values are in good agreement with the experimental values, which validates the proposed model. Moreover, the proposed contact model is compared with previous contact models that adopt Coulomb friction law and meanwhile ignore stator teeth by assuming teeth surfaces to be continuous. The comparison results show that the proposed model is more accurate than previous models.