Efficient Modulation of Friction in Ultrasonic Motors Using Functional Fluids
Ultrasonic motors (USMs) have been extensively studied for three decades, due to their attractive features, such as high torque at low speed, simple structure, and precise positioning capability. However, since USMs are driven by the friction force between the rotor and the stator in most cases, they inherently possess the friction loss and the wear of contact materials, which cause their low effi
