Autonomous Steering of Concentric Tube Robots for Enhanced Force/Velocity Manipulability

Mohsen Khadem, John O'Neill, Zisos Mitros, Lyndon Da Cruz, Christos Bergeles

Research output: Contribution to journalConference paperpeer-review

14 Citations (Scopus)
216 Downloads (Pure)


Concentric tube robots (CTR) can traverse tightly curved paths and offer dexterity in constrained environments, making them advantageous for minimally invasive surgical scenarios that experience strict anatomical and surgical constraints. Their shape is controlled via rotation and translation of several concentrically arranged super-elastic precurved tubes that form the robot backbone. As the elastic energy accumulated in the backbone due to bending and twist of the tubes increases, robots can exhibit sudden snapping motions, which can damage the surrounding tissues. In this paper, we proposed an approach for closed-loop steering of a redundant CTR that allows for snap-free motion and enhances its force/velocity manipulability, increasing the capacity of the robot to move and/or exercise forces along any direction. First, a controller stabilizes the CTR end-effector on a desired time-variant trajectory. Next, an online optimizer uses the robot's redundant Degrees of Freedom (DoF) to reshape its manipulability in real-time and steer it away from potentially snapping configurations or increase its capacity in delivering force payloads. Simulations and experiments demonstrate the performance of the proposed control strategy. The controller can steer a generally unstable CTR along trajectories while avoiding instabilities with a mean error of 850\mum, corresponding to 0.6% of arclength, and improves robot ability to exercise forces by 55%.

Original languageEnglish
Pages (from-to)2197-2204
Number of pages8
Journal2019 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)
Early online date27 Jan 2020
Publication statusPublished - 27 Jan 2020
Event2019 IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2019 - Macau, China
Duration: 3 Nov 20198 Nov 2019


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