Precisely positioning the tip of an instrument inserted through an orifice with a free wrist robot: application to prostate biopsies

Purpose Robots with a spherical unactuated wrist can be used for minimally invasive surgery. With such a robot, positioning the wrist center controls the instrument tip position when assuming that the insertion site behaves like a lever with a fixed and known fulcrum. In practice, this assumption is...

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Bibliographic Details
Published in:International journal for computer assisted radiology and surgery 2018-05, Vol.13 (5), p.611-618
Main Authors: Chalard, Rémi, Reversat, David, Morel, Guillaume, Mozer, Pierre, Vitrani, Marie-Aude
Format: Article
Language:English
Subjects:
Automatic
Biopsy
Computer Imaging
Computer Science
Control equipment
Engineering Sciences
Health Informatics
Imaging
Laboratories
Laboratory equipment
Medicine
Medicine & Public Health
Orifices
Original Article
Pattern Recognition and Graphics
Prostate
Radiology
Robot control
Robotic surgery
Robots
Surgery
Vision
Wrist
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Summary:Purpose Robots with a spherical unactuated wrist can be used for minimally invasive surgery. With such a robot, positioning the wrist center controls the instrument tip position when assuming that the insertion site behaves like a lever with a fixed and known fulcrum. In practice, this assumption is not always respected. In this paper we first study the practical consequences of this problem in terms of tip precision positioning. We then propose a robotic control scheme that improves the precision compared to the fixed point assumption approach. Methods In the first part of the paper, data recorded during robot-assisted transrectal needle positioning for prostate biopsies (nine patients) are exploited to quantify the positioning error induced by the use of a fixed point hypothesis in the positioning process. In the second part of the paper advanced control techniques allow for the online identification of a locally linear system that describes a model characterized by anisotropy and center displacement. A laboratory apparatus is used to demonstrate the resulting improvement on tip positioning precision. Results Errors obtained by processing the clinical data reach 7.5 mm at the tip in average. Errors obtained with the laboratory apparatus drop from 2.4 mm in average to 0.8 mm when using real-time model update.
ISSN:1861-6410
1861-6429
DOI:10.1007/s11548-018-1718-6