Virtual remote center of motion control for needle placement robots

Emad M. Boctor, Robert J. Webster, Herve Mathieu, Allison M. Okamura, Gabor Fichtinger

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Objective: We present an algorithm that enables percutaneous needle-placement procedures to be performed with unencoded, unregistered, minimally calibrated robots while removing the constraint of placing the needle tip on a mechanically enforced Remote Center of Motion (RCM). Materials and Methods: The algorithm requires only online tracking of the surgical tool and a five-degree-of-freedom (5-DOF) robot comprising three prismatic DOF and two rotational DOF. An incremental adaptive motion control cycle guides the needle to the insertion point and also orients it to align with the target-entry-point line. The robot executes RCM motion without having a physically constrained fulcrum point. Results: The proof-of-concept prototype system achieved 0.78 mm translation accuracy and 1.4° rotational accuracy (this is within the tracker accuracy) within 17 iterative steps (0.5-1 s). Conclusion: This research enables robotic assistant systems for image-guided percutaneous procedures to be prototyped/constructed more quickly and less expensively than has been previously possible. Since the clinical utility of such systems is clear and has been demonstrated in the literature, our work may help promote widespread clinical adoption of this technology by lowering system cost and complexity.

Original languageEnglish (US)
Pages (from-to)175-183
Number of pages9
JournalComputer Aided Surgery
Issue number5
StatePublished - 2004
Externally publishedYes


  • Image guidance
  • Medical robotics
  • Needle insertion
  • Visual feedback

ASJC Scopus subject areas

  • Surgery
  • Radiology Nuclear Medicine and imaging


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