<title>Rotary ultrasonic motors actuated by traveling flexural waves</title>

Abstract

Efficient miniature actuators that are compact and consume low power are needed to drive space and planetary mechanisms in future NASA missions. Ultrasonic rotary motors have the potential to meet this NASA need and they are developed as actuators for miniature telerobotic applications. These motors have emerged in commercial products but they need to be adapted for operation at the harsh space environments that include cryogenic temperatures and vacuum and also require effective analytical tools for the design of efficient motors. A finite element analytical model was developed to examine the excitation of flexural plate wave traveling in a piezoelectrically actuated rotary motor. The model uses 3D finite element and equivalent circuit models that are applied to predict the excitation frequency and modal response of the stator. This model incorporates the details of the stator including the teeth, piezoelectric ceramic, geometry, bonding layer, etc. The theoretical predictions were conoborated experimentally for the stator. In parallel, efforts have been made to determine the thermal and vacuum performance of these motors. Experiments have shown that the motor can sustain at least 230 temperature cycles from 0°C to -90°C at 7 Ton pressure significant performance change. Also, in an earlier study the motor lasted over 334 hours at -150°C and vacuum. To explore telerobotic applications for USMs a robotic arm was constructed with such motors.

Large-Scale Piezoelectric-Based Systems for More Electric Aircraft Applications

“…Based on these driving methods, the ultrasonic actuator can be classified into two groups: standing wave [131][132][133] (Figure 13a) and traveling wave [39,134,135] (Figure 13b). The ultrasonic concept could be used for both linear motion [136] and rotary motion [135,137]. The elliptic motion could be generated from the tip of each piezoelectric element or the combination motions of the whole stator [130].…”

Wave propagations of curvilinear motors driven by partially laminated piezoelectric actuators

“…There are many types of piezoelectric motors classified by their movements, e.g. (1) linear motors [5][6][7] and (2) rotary motors [8]. In addition to these, a 'curvilinear motor' is a relatively new type of piezoelectric motor [9], which provides curvilinear motions for the rotors.…”

“…The fundamental principle of the traveling wave ultrasonic motors is based on the traveling waves generated on the stator driving the rotor [2][3][4]8]. Traveling waves of ultrasonic rotary motors are generated by piezoelectric actuators bonded on a circular disk or ring with assumed free boundary conditions.…”