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Proceedings Paper

Design of a decoupled MRI-compatible force sensor using fiber bragg grating sensors for robot-assisted prostate interventions
Author(s): Reza Monfaredi; Reza Seifabadi; Gabor Fichtinger; Iulian Iordachita
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Paper Abstract

During prostate needle insertion, the gland rotates and displaces resulting in needle placement inaccuracy. To compensate for this error, we proposed master-slave needle steering under real-time MRI in a previous study. For MRI-compatibility and accurate motion control, the master (and the slave) robot uses piezo actuators. These actuators however, are non-backdrivable. To cope with this issue, force sensor is required. Force sensor is also required at the slave side to reflect the insertion force to clinician’s hand through the master robot. Currently, there is no MRI-compatible force sensor commercially available. In order to generate a combination of linear and rotary motions for needle steering, this study is seeking to develop a MRI-compatible 2 Degrees of Freedom (DOF) force/torque sensor. Fiber Brag Grating (FBG) strain measuring sensors which are proven to be MRI-compatible are used. The active element is made of phosphor-bronze and other parts are made of brass. The force and torque measurements are designed to be entirely decoupled. The sensor measures -20 to 20 N axial force with 0.1 N resolution, and -200 to 200 Nmm axial torque with 1 Nmm resolution. Analytical and Finite Element (FE) analyses are performed to ensure the strains are within the measurable range of the FBG sensors. The sensor is designed to be compact (diameter =15 mm, height =20 mm) and easy to handle and install. The proposed sensor is fabricated and calibrated using a commercial force/torque sensor.

Paper Details

Date Published: 12 March 2013
PDF: 9 pages
Proc. SPIE 8671, Medical Imaging 2013: Image-Guided Procedures, Robotic Interventions, and Modeling, 867118 (12 March 2013); doi: 10.1117/12.2008160
Show Author Affiliations
Reza Monfaredi, Johns Hopkins Univ. (United States)
Reza Seifabadi, Queen's Univ. (Canada)
Gabor Fichtinger, Queen's Univ. (Canada)
Iulian Iordachita, Johns Hopkins Univ. (United States)

Published in SPIE Proceedings Vol. 8671:
Medical Imaging 2013: Image-Guided Procedures, Robotic Interventions, and Modeling
David R. Holmes III; Ziv R. Yaniv, Editor(s)

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