Design of a hybrid transducer type ultrasonic motor. 
The authors present a design method for a hybrid transducer-type ultrasonic motor (HTUSM) for practical use.  They introduce a simple equivalent circuit that expresses the unique operation mechanism of the hybrid transducer-type motor.  A numerical simulation based on the model enables them to predict the motor characteristics such as the maximum torque and the no-load revolution speed.  In addition, for the purpose of efficient design and physical interpretation of the phenomena, they discuss analytically the maximum torque of a special case and develop two design charts for the prediction of the no-load speed of the motor.