Ultrasonic rotary motors have the potential to meet this NASA need and they are developed as actuators for miniature telerobotic applications .Tehse motors are being adapted for operation at the harsh space environmetns that include cyrogenic temperatures and vacuum and analytical tools for the design of efficient motors are being developed. A hybrid analytical model was developed to address a complete ultrasonic motor as a system. Included in this model is the influence of the rotor dynamics, which was determined experimentally to be improtant to the motor performance. The anlaysis employs a 3D finite element model to express the dynamic characteristics of the stator with piezoelectric elements and rotor. The details of the stator including the teeth, piezoelectric ceramic, geometry, bonding layer, etc. are included to support practical USM designs. A brush model is used for the interface layer and Coulomb's law for the friction between the stator and the rotor. The theoretical predictions were corroborated experimetnally for the motor. In parallel, efforts have been made to determine the thermal and vacuum performance of these motors. To explroe telerobotic applications for USMs a robotic arm was constructed with such motors.
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