A Hybrid Ultrasonic Motor and Electrorheological Fluid Clutch Actuator for Force-Feedback in MRI/fMRI

This paper presents a safe, electrically powered MR-compatible actuator with a large range of output impedance, which can be used at the entry of the scanner bore. This actuator is composed of an ultrasonic motor (USM) and a torque-controlled electrorheological fluid clutch which modulates the output torque of the USM. This paper describes the developments on the electrorheological fluid (ERF) clutch and its high voltage driver. The performances of the ERF brake constituting the clutch are evaluated, and its torque range is adapted using an epicyclic differential. The transmissible torque of the ERF clutch, i.e., the maximum system output torque, is 94.4 mNm and its drag torque is 2.6 mNm. The MR compatibility of the complete hybrid actuator is shown in extensive tests including subtraction of images and comparison of signal-to-noise ratios in powered and unpowered conditions. This novel MR-compatible actuator may be used to study the neural control of the hand.

Published in:
2008 30Th Annual International Conference Of The Ieee Engineering In Medicine And Biology Society, Vols 1-8, 3438-3442
Presented at:
30th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society, Vancouver, CANADA, Aug 20-24, 2008
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 Record created 2010-11-30, last modified 2018-01-28

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