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Stretchable artificial muscles from coiled polymer fibers

Journal Article


Abstract


  • Soft robots are being developed to mimic the movement of biological organisms and as wearable

    garments to assist human movement in rehabilitation, training, and tasks encountered in

    functional daily living. Stretchable artificial muscles are well suited as the active mechanical

    element in soft wearable robotics, and here the performance of highly stretchable and compliant

    polymer coil muscles are described and analyzed. The force and displacements generated by

    a given stimulus are shown to be determined by the external loading conditions and the main

    material properties of free stroke and stiffness. Spring mechanics and a model based on a single

    helix are used to evaluate both the coil stiffness and the mechanism of coil actuation. The latter is

    directly coupled to a torsional actuation in the twisted fiber that forms the coil. The single helix

    model illustrates how fiber volume changes generate a partial fiber untwist, and spring mechanics

    shows how this fiber untwist generates large tensile strokes and high gravimetric work outputs in

    the polymer coil muscles. These analyses highlight possible as yet unexplored means for further

    enhancing the performance of these systems.

Publication Date


  • 2016

Citation


  • Spinks, G. M. (2016). Stretchable artificial muscles from coiled polymer fibers. Journal of Materials Research, 31 (19), 2917-2927.

Number Of Pages


  • 10

Start Page


  • 2917

End Page


  • 2927

Volume


  • 31

Issue


  • 19

Abstract


  • Soft robots are being developed to mimic the movement of biological organisms and as wearable

    garments to assist human movement in rehabilitation, training, and tasks encountered in

    functional daily living. Stretchable artificial muscles are well suited as the active mechanical

    element in soft wearable robotics, and here the performance of highly stretchable and compliant

    polymer coil muscles are described and analyzed. The force and displacements generated by

    a given stimulus are shown to be determined by the external loading conditions and the main

    material properties of free stroke and stiffness. Spring mechanics and a model based on a single

    helix are used to evaluate both the coil stiffness and the mechanism of coil actuation. The latter is

    directly coupled to a torsional actuation in the twisted fiber that forms the coil. The single helix

    model illustrates how fiber volume changes generate a partial fiber untwist, and spring mechanics

    shows how this fiber untwist generates large tensile strokes and high gravimetric work outputs in

    the polymer coil muscles. These analyses highlight possible as yet unexplored means for further

    enhancing the performance of these systems.

Publication Date


  • 2016

Citation


  • Spinks, G. M. (2016). Stretchable artificial muscles from coiled polymer fibers. Journal of Materials Research, 31 (19), 2917-2927.

Number Of Pages


  • 10

Start Page


  • 2917

End Page


  • 2927

Volume


  • 31

Issue


  • 19