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arXiv · 2510.23954

A Comprehensive General Model of Tendon-Actuated Concentric Tube Robots with Multiple Tubes and Tendons

Pejman Kheradmand·Behnam Moradkhani·Raghavasimhan Sankaranarayanan·Kent K. Yamamoto·Tanner J. Zachem·Patrick J. Codd·Yash Chitalia·Pierre E. Dupont
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Abstract

Tendon-actuated concentric tube mechanisms combine the advantages of tendon-driven continuum robots and concentric tube robots while addressing their respective limitations. They overcome the restricted degrees of freedom often seen in tendon-driven designs, and mitigate issues such as snapping instability associated with concentric tube robots. However, a complete and general mechanical model for these systems remains an open problem. In this work, we propose a Cosserat rod-based framework for modeling the general case of $n$ concentric tubes, each actuated by $m_i$ tendons, where $i = \{1, \ldots, n\}$. The model allows each tube to twist and elongate while enforcing a shared centerline for bending. We validate the proposed framework through experiments with two-tube and three tube assemblies under various tendon routing configurations, achieving tip prediction errors $<4\%$ of the robot's total length. We further demonstrate the model's generality by applying it to existing robots in the field, where maximum tip deviations remain around $5\%$ of the total length. This model provides a foundation for accurate shape estimation and control of advanced tendon-actuated concentric tube robots.

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Pejman Kheradmand, Behnam Moradkhani, Raghavasimhan Sankaranarayanan, Kent K. Yamamoto, Tanner J. Zachem, Patrick J. Codd, Yash Chitalia, Pierre E. Dupont. 2025-10-28. A Comprehensive General Model of Tendon-Actuated Concentric Tube Robots with Multiple Tubes and Tendons. https://arxiv.org/abs/2510.23954

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