Working principle and design of a double cylinders type traveling wave ultrasonic motor using composite transducer

A double cylinders type traveling wave ultrasonic motor using composite transducer was proposed. The proposed stator contained two cylinders and one composite transducer, and the transducer located on the outer surfaces of cylinders. The composite transducer included two exponential horns located on leading ends, and the horns insected with the cylinders at tip ends. Two degenerated flexural vibration modes spatially and temporally orthogonal to each other were excited in each cylinder by the composite transducer. In this new design, a single transducer could excite two flexural traveling waves in the cylinders. Thus, elliptical motions were achieved at the particles on the teeth. The working principle of the proposed motor was analyzed. The cylinder and transducer were designed with FEM. The resonant frequencies of two vibration modals of the stator were tuned to be the same, and the motion trajectories of nodes on the teeth were analyzed. Transient analysis results show that the motion trajectories of teeth are ellipses. The results of this paper can guide the development of this new type of ultrasonic motor.