Lab Papers (GRASP)

Document Type

Conference Paper

Subject Area


Date of this Version


Publication Source

2022 IEEE International Conference on Robotics and Automation (ICRA))

Bib Tex

@ARTICLE{tsm, author={Misra, Shivangi and Sung, Cynthia}, JOURNAL={IEEE International Conference on Robotics and Automation (ICRA)}, title={Forward Kinematics and Control of a Tunable-Stiffness 3-D Continuum Manipulator}, year={2022}}


In this work, we consider the problem of controlling the end effector position of a continuum manipulator through local stiffness changes. Continuum manipulators offer the advantage of continuous deformation along their lengths, and recent advances in smart material actuators further enable local compliance changes, which can affect the manipulator's bulk motion. However, leveraging local stiffness change to control motion remains lightly explored. We build a kinematic model of a continuum manipulator as a sequence of segments consisting of symmetrically arranged springs around the perimeter of every segment, and we show that this system has a closed form solution to its forward kinematics. The model includes common constraints such as restriction of torsional or shearing movement. Based on this model, we propose a controller on the spring stiffnesses for a single segment and provide provable guarantees on convergence to a desired goal position. The results are verified in simulation and compared to physical hardware.

Copyright/Permission Statement

© 2022 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.


Continuum Manipulator, Tunable Stiffness, Soft Robotics, Control, Modeling

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Robotics Commons



Date Posted: 11 May 2022

This document has been peer reviewed.