Array-driven ultrasonic microactuators

The authors present the design of an array-driven ultrasonic microactuator. Unlike a conventional ultrasonic motor, the array-driven ultrasonic microactuator consists of many distributed modules, using a concept similar to that of the distributed microactuator array. With a conventional ultrasonic motor, it is difficult to control an object locally and to obtain sufficient resolution of the rotor position and orientation without closed-loop control, since the motion of the rotor is produced by traveling waves on the whole diaphragm. However, an array-driven ultrasonic microactuator can control the motion with high accuracy even in open-loop control, because it can control the motion of each distributed module. It uses perpendicular motion, which is suitable for an electrostatic-force-type actuator. Perpendicular motions produced by two transducers in each module are mechanically transformed into circular motion, and a set of circular motions of the micromodules induces motion in the object.<>