Early studies of a transmission mechanism for MR-guided interventions

Haoran Zhao, Xin Liu, Habib M. Zaid, Dipan J. Shah, Michael J. Heffernan, Aaron T. Becker, Nikolaos V. Tsekos

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


Magnetic resonance imaging (MRI)-guided, manipulator-assisted interventions have the potential to improve patient outcomes. This work presents a force transmission mechanism, called solid-media transmission (SMT), for actuating manipulators inside MRI scanners. The SMT mechanism is based on conduits filled with spheres and spacers made of a nonmagnetic, nonconductive material that forms a backbone for bidirectional transmission. Early modeling and experimental studies assessed SMT and identified limitations and improvements. Simulations demonstrated the detrimental role of friction, which can be alleviated with a choice of low friction material and long spacers. However, the length of the spacer is limited by the desired bending of the conduit. A closed-loop control law was implemented to drive the SMT. The 3rd order system fit ratio is 92.3%. A 1-m long SMT was experimentally tested under this closed-loop controller with heuristically set parameters using a customized benchtop setup. For commanded displacements of 1 to 50 mm, the SMT-actuated 1 degree of freedom stage exhibited sub-millimeter accuracy, which ranged from 0.109 ± 0:057 mm to 0.045 ± 0.029 mm depending on the commanded displacement. However, such accuracy required long control times inversely proportional to displacement ranging from 7.56 ± 1.85s to 2.53 ± 0.11s. This was attributed to friction as well as backlash which is due to suboptimal packing of the media. In MR studies, a 4-m long SMT-actuated 1 DoF manipulator was powered by a servo motor located inside the scanner room but outside the 5 Gauss line of the magnet. With shielding and filtering, the SNR of MR images during the operation of the servo motor and SMT- actuation was found to be 89 ± 9% of the control case.

Original languageEnglish (US)
Title of host publicationProceedings - 2017 IEEE 17th International Conference on Bioinformatics and Bioengineering, BIBE 2017
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages7
ISBN (Electronic)9781538613245
StatePublished - Jan 8 2018
Event17th IEEE International Conference on Bioinformatics and Bioengineering, BIBE 2017 - Herndon, United States
Duration: Oct 23 2017Oct 25 2017


Other17th IEEE International Conference on Bioinformatics and Bioengineering, BIBE 2017
Country/TerritoryUnited States


  • MR compatible
  • Robotic Actuator
  • Solid media transmission

ASJC Scopus subject areas

  • Information Systems
  • Biomedical Engineering
  • Modeling and Simulation
  • Signal Processing
  • Health Informatics


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