A Sliding-Rod Variable-Strain Model for Concentric Tube Robots

Federico Renda, Conor Messer, Caleb Rucker, Frederic Boyer

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


In this work, the Piecewise Variable-strain (PVS) approach is applied to the case of Concentric Tube Robots (CTRs) and extended to include the tubes' sliding motion. In particular, the currently accepted continuous Cosserat rod model is discretized onto a finite set of strain basis functions. At the same time, the insertion and rotation motions of the tubes are included as generalized coordinates instead of boundary kinematic conditions. Doing so, we obtain a minimum set of closed-form algebraic equations that can be solved not only for the shape variables but also for the actuation forces and torques for the first time. This new approach opens the way to torque-controlled CTRs, which is poised to enhance elastic stability and improve interaction forces' control at the end-effector.

Original languageBritish English
Article number9368976
Pages (from-to)3451-3458
Number of pages8
JournalIEEE Robotics and Automation Letters
Issue number2
StatePublished - Apr 2021


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