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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.

Echo-encephalography, described by LekseU (1955), consists in the transmission into the skull of a rather narrow beam of ultrasound, part of which is reflected to the transmitter. This technique enables one to measure the distance between the reflecting surfaces arid the transmitter, in order to derive certain conclusions about structures existing within the skull.It is obvious that this method offers certain advantages to the usual X-ray techniques, for in the latter ease the total quantity of transmitted energy is visualized on the X-ray film as a density. On a normal X-ray film the skull appears to be "empty", the differences in density of the various structures being too small to cause appreciable differences in density on the X-ray film.Only when the skull contains special struetnres with a considerably differing density (nearly always ealeifications) is it possible to visualize these structures. Therefore we are obliged to have recourse to the use of contrast media of differing density to visualize certain structures, which, however, leads to an intervention not always acceptable for the patient.By the use of echo-eneephalography such an intervention can be avoided. One could ask which structures in the skull contents are involved in the reflection of the ultrasound. It appears that such structures must be present at several places, for reflections are obtained at nearly every direction of transmission, so that it is not probable that a specific structure, for instance the pineal body, should be the unique cause of the reflections.