Development of an ultrasonic motor as a fine-orienting stage

Describes the development of an application of a traveling-wave-type ultrasonic motor as an orienting stage with the precision to cover the fine rotation of a tool at a submicrometer-level orienting system. The defined term of orienting here implies the micro positioning with a fine rotation motion. The proposed fine-orienting stage consists of a half spherical-type rotor and three pieces of ring-type stators. The fine rotation at the center of the rotor is determined by controlling friction forces, which generate rotation at the three contact points between the rotor and the stators. A method to rotate the rotor in fine rotation to attain a desired orientation is also proposed. Three different sizes of ultrasonic motors are presented to verify performance of the ultrasonic motor as a fine-orienting stage and to investigate an extreme of the ultrasonic motor motion. The results of the three models of the orienting stages are discussed and the validity of the ultrasonic motor as a fine-orienting stage is confirmed