Three-Dimensional-Printable Thermoactive Helical Interface With Decentralized Morphological Stiffness Control for Continuum Manipulators

Hadi Sadati, Luis Sullivan, Ian D Walker, Kaspar Althoefer, Thrishantha Nanayakkara

Research output: Contribution to journalArticle (Academic Journal)peer-review

7 Citations (Scopus)
192 Downloads (Pure)


We present a three-dimensional (3-D)-printable thermoactive scale jamming interface as a new way to control a continuum manipulator dexterity by taking inspiration from the helical arrangement of fish scales. A highly articulated helical interface is 3-D-printed with thermoactive functionally graded joints using a conventional 3-D printing device that utilizes UV curable acrylic plastic and hydroxylated wax as the primary and supporting material. The joint compliance is controlled by regulating wax temperature in phase transition. Empirical feed-forward control relations are identified through comprehensive study of the wax melting profile and actuation scenarios for different shaft designs to achieve desirable repeatability and response time. A decentralized control approach is employed by relating the mathematical terms of the Cosserat beam method to their morphological counterparts in which the manipulator local anisotropic stiffness is controlled based on the local stress and strain information. As a result, a minimalistic central controller is designed in which the joints' thermomechanical states are observed using a morphological observer, an external fully monitored replica of the observed system with the same inputs. Preliminary results for passive shape adaptation, geometrical disturbance rejection, and task space anisotropic stiffness control are reported by integrating the interface on a continuum manipulator.
Original languageEnglish
Pages (from-to)2283-2290
Number of pages8
JournalIEEE Robotics and Automation Letters
Issue number3
Early online date12 Feb 2018
Publication statusPublished - Jul 2018


  • Flexible robots
  • compliance and impedance control
  • medical robots and systems


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  • Toward Computing with Spider Webs: Computational Setup Realization

    Sadati, H. & Williams, T., 7 Jul 2018, Biomimetic and Biohybrid Systems: 7th International Conference, Living Machines 2018, Paris, France, July 17–20, 2018, Proceedings. Springer, Cham, p. 391-402 12 p. (Lecture Notes in Artificial Intelligence; vol. 10928).

    Research output: Chapter in Book/Report/Conference proceedingConference Contribution (Conference Proceeding)

    Open Access
    3 Citations (Scopus)
    308 Downloads (Pure)

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