Tendon Driven Continuum Robots

Continuous motion is most commonly achieved by using tendons in continuum robotics. In so called tendon-driven continuum robots (TDCR) several tendons are routed alongside the robot's flexible backbone and fixed at different locations. TDCR can consist of multiple stacked segments, where each segment end is defined by the termination of one or multiple tendons. When pulling these tendons, a load will be applied to the compliant backbone and the corresponding segment will bend in the direction of the routed tendon. Tendon actuation is an extrinsic actuation principle, as no actuators are located within the robot's structure.
General structure of a tendon-driven continuum robot. Tendons terminate at the end disk of each segment to actuate it. They are routed in parallel to the central backbone. For spatial bending either 3 tendons or 2 antagonistic pairs are used. This example TDCR has two segments actuated by antagonistic tendon pairs.

TDCR Design

At CRL, we are at the forefront of pioneering tendon-driven continuum robots. Our designs include multi-segmented continuum robots that inherently exhibit follow-the-leader motion capabilities, a critical feature for navigating complex environments. Additionally, we are developing robotic segments capable of integrating the three fundamental motion primitives: spatial bending, twisting, and extension/contraction. This versatility enables our robots to perform a wide range of tasks with unprecedented dexterity and precision, pushing the boundaries of what is possible in the field of robotics.

Reducing Complexity through Mechanical Design and Computational Means

To reduce the number of actuators in multi-segmented continuum robots, we explore mechanical modifications to induce internal constraints and, consequently, curvature variation. This approach employs the principle of shape locking, where locking portions of the robot inhibits relative motion between its components. As a result, the free portion can respond to tendon actuation, while the locked portion maintains its general shape.

Magnetic Locking

In collaboration with Dr. Eric Diller's lab, we proposed a magnetic locking mechanism. This work enables two curvatures in a single segment tendon-driven continuum robot. We showed that multiple of these magnetic locking mechanisms can be addressable actuated, demonstrating the potential of achieving a greater number of curvatures in a single segment.

Actuation Strategies

Furthermore, we address the gap in physics-based models used to predict the robots' behaviour by proposing a 3D static model that considers the length constraints of locked portions, along with backbone twist, frictional, and gravitational forces. This approach generalizes to any continuum robot, which allows to impose length constraints actively. Using this modelling approach, we explored different actuation strategies computationally. We found that three or more locking mechanisms can be used to achieve the same robot shape but with different stiffness properties.

Funding

  • XSeed, University of Toronto (2019-2021)
  • Canada Foundation for Innovation, John R. Evans Leaders Fund
  • Ontario Research Fund, Research Infrastructure

Publications

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A Lightweight Modular Segment Design for Tendon-Driven Continuum Robots with Pre-Programmable Stiffness

Puspita Triana Dewi, Priyanka Rao, Jessica Burgner-Kahrs

IEEE International Conference on Soft Robotics, 2024.

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Stability Analysis of Tendon Driven Continuum Robots and Application to Active Softening

Quentin Peyron, Jessica Burgner-Kahrs

IEEE Transactions on Robotics, 40:85-100, 2023.

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Modeling and Analysis of Tendon-driven Continuum Robots for Rod-based Locking

Priyanka Rao, Chloe Pogue, Quentin Peyron, Eric D. Diller, Jessica Burgner-Kahrs

IEEE Robotics and Automation Letters, 8(6):3126-3133, 2023.

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Multiple Curvatures in a Tendon-Driven Continuum Robot Using a Novel Magnetic Locking Mechanism.

Chloe Pogue, Priyanka Rao, Quentin Peyron, Jongwoo Kim, Jessica Burgner-Kahrs, Eric D. Diller

IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2022.

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Shape Representation and Modeling of Tendon-Driven Continuum Robots Using Euler Arc Splines

Priyanka Rao, Quentin Peyron, Jessica Burgner-Kahrs

IEEE Robotics and Automation Letters, 7 (3), pp. 8114 - 8121, 2022.

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FAS - A Fully Actuated Segment for Tendon-Driven Continuum Robots

Reinhard Grassmann, Priyanka Rao, Quentin Peyron, Jessica Burgner-Kahrs

Frontiers in Robotics and AI, 9:873446 (19 pages), 2022.

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How to Model Tendon-Driven Continuum Robots and Benchmark Modelling Performance

Priyanka Rao, Quentin Peyron, Sven Lilge, Jessica Burgner-Kahrs

Frontiers in Robotics and AI, 7 (630245), pp. 20, 2021.

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Tendon-driven Continuum Robots with Extensible Sections - A Model-based Evaluation of Path Following Motions

E Amanov, T -D Nguyen, J Burgner-Kahrs

International Journal of Robotics Research, 40 (1), pp. 7-23, 2021.

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Comparison of Modeling Approaches for a Tendon Actuated Continuum Robot with Three Extensible Segments

Mohamed Taha Chikhaoui, Sven Lilge, Simon Kleinschmidt, Jessica Burgner-Kahrs

IEEE Robotics & Automation Letters, 4 (2), pp. 989 - 996, 2019.

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Toward Improving Path Following Motion - Hybrid Continuum Robot Design

E Amanov, J Granna, J Burgner-Kahrs

IEEE International Conference on Robotics and Automation, pp. 4666-4672, 2017.

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On the Merits of Helical Tendon Routing in Continuum Robots

Julia Starke, Ernar Amanov, Mohamed Taha Chikhaoui, Jessica Burgner-Kahrs

IEEE International Conference on Robotics and Automation, pp. 6470–6476, 2017.

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Considerations for follow-the-leader motion of extensible tendon-driven continuum robots

Maria Neumann, Jessica Burgner-Kahrs

IEEE International Conference on Robotics and Automation, pp. 917–923, ISBN -- 978-1-4673-8026-3., 2016.

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A Tendon-Driven Continuum Robot with Extensible Sections

Thien-Dang Nguyen, Jessica Burgner-Kahrs

IEEE/RSJ International Conference on Intelligent Robots and Systems, 2015.