Support Mechanism for the Ball Rotor in the Three-Degree-of-Freedom Ultrasonic Motor

Three types of support mechanism for the ball rotor of a three-degree-of-freedom ultrasonic motor with a single stator have been proposed and studied in order to achieve a large output torque. These support mechanisms could apply a sufficient preload to the ball rotor, and the three-degree-of-freedom rotational movements of the ball rotor were possible. The output torque were 1.7 kgf·cm for the z-axis rotation and 2.8 kgf·cm for the x-axis rotation at a preload of 4 kgf. The no-load maximum rotation speeds were 5 rps for the z-axis rotation and 4.3 rps for the x-axis rotation.