Design of an actively controlled steerable needle with tendon actuation and FBG-based shape sensing

摘要

This work presents a new steerable needle to facilitate active steering toward predefined target locations. It focuses on mechanical aspects and design choices in relation to the observed response in a tissue phantom. Tip steering with two rotational degrees of freedom was achieved by a tendon actuated ball joint mechanism. During insertion, the flexible cannula bends as a result of asymmetric tip-tissue interaction forces. The stylet was equipped with fiber Bragg gratings to measure the needle shape and tip position during use. A PI-controller was implemented to facilitate steering to predefined targets. During the validation study, nine targets were defined at a depth of 100 mm below the gelatin surface. One was located below the insertion point, the others at a radial offset of 30 mm in each of the eight principle steering directions. Per location, six repetitions were performed. The targeting accuracy was 6.2 +/- 1.4 mm (mean +/- std). The steering precision was 2.6 +/- 1.1 mm. The ability to steer with this new needle steering approach is presented and the mechanical characteristics are discussed for this representative subset of steering directions. (C) 2015 IPEM. Published by Elsevier Ltd. All rights reserved.