Load characteristics of ultrasonic motor with a longitudinal-torsional converter and various nonlinear springs for inducing static pressure

Ultrasonic rotary motors using a longitudinal-torsional vibration converter and a nonlinear spring for inducing static pressure were studied. Using nonlinear static pressure source, static pressure (frictional driving force) increases during forward duty cycle, and the force during opposite retracting cycle decreases resulting small frictional loss, and the load characteristics of the motor were significantly improved. Nonlinear static and dynamic characteristics of various material spring were measured