Dual traveling wave rotary ultrasonic motor with single active vibrator

Traveling wave rotary ultrasonic motor with double vibrators can improve the output performance effectively. However, the rotor has to be energized through a slip ring, which increases the complexity and reduces the reliability. Inheriting the concept of two traveling waves propagating in the stator and rotor, a dual traveling wave rotary ultrasonic motor energized only in the stator is proposed. By analyzing the oscillatory differential equation and the contact particles motion, a traveling wave is found in the rotor and the drive mechanism of dual traveling wave is studied. With the resonant rotor adopted, the consistent eigenfrequencies are calculated by finite element method and verified by an impedance analyzer. The performance experiment presents that the dual traveling wave rotary ultrasonic motor is superior to the motor with single traveling wave. The no-load speed is 60 rpm and the stalling torque is 0.85 Nm. Additionally, compared with a reported motor with double vibrators, the proposed motor presents the better output performance and the simpler design.