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Dynamics for variable length multisection continuum arms

Godage, Isuru S.; Medrano-Cerda, Gustavo A.; Branson, David T.; Guglielmino, Emanuele; Caldwell, Darwin G.

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Isuru S. Godage

Gustavo A. Medrano-Cerda

David T. Branson

Emanuele Guglielmino

Darwin G. Caldwell


Variable length multisection continuum arms are a class of continuum robotic manipulators that generate motion by structural mechanical deformation. Unlike most continuum robots, the sections of these arms do not have (central) supporting flexible backbone, and are actuated by multiple variable length actuators. Because of the constraining nature of actuators, the continuum sections can bend and/or elongate (compress) depending on the elongation/contraction characteristics of the actuators being used. Continuum arms have a number of distinctive differences with respect to traditional rigid arms namely: smooth bending, high inherent compliance, and adaptive whole arm grasping. However, due to numerical instability and the complexity of curve parametric models, there are no spatial dynamic models for multisection continuum arms. This paper introduces novel spatial dynamics and applies these to variable length multisection continuum arms with any number of sections. An efficient recursive computational scheme for deriving the equations of motion is presented. This is applied in a general form based on structurally accurate and numerically well-posed modal kinematics that assumes circular arc deformation of continuum sections without torsion. It is shown that the proposed modal dynamics are highly scalable, producing efficient and accurate numerical results. The spatial dynamic simulation results are experimentally validated using a pneumatic muscle actuated multisection prototype continuum arm. For the first time this enables investigation of spatial dynamic effects in this class of continuum arms.


Godage, I. S., Medrano-Cerda, G. A., Branson, D. T., Guglielmino, E., & Caldwell, D. G. (2016). Dynamics for variable length multisection continuum arms. International Journal of Robotics Research, 35(6),

Journal Article Type Article
Acceptance Date Aug 15, 2015
Online Publication Date Sep 3, 2015
Publication Date May 1, 2016
Deposit Date May 9, 2016
Publicly Available Date May 9, 2016
Journal International Journal of Robotics Research
Print ISSN 0278-3649
Electronic ISSN 0278-3649
Publisher SAGE Publications
Peer Reviewed Peer Reviewed
Volume 35
Issue 6
Keywords continuum arms, modal shape functions, spatial dynamics, recursive computations
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