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A soft robot that adapts to environments through shape change

Nature Machine Intelligence volume 3, pages 51–59 (2021)Cite this article

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An Author Correction to this article was published on 01 April 2024

This article has been updated

A preprint version of the article is available at arXiv.

Abstract

Many organisms, including various species of spiders and caterpillars, change their shape to switch gaits and adapt to different environments. Recent technological advances, ranging from stretchable circuits to highly deformable soft robots, have begun to make shape-changing robots a possibility. However, it is currently unclear how and when shape change should occur, and what capabilities could be gained, leading to a wide range of unsolved design and control problems. To begin addressing these questions, here we manually design, simulate, and build a soft robot that utilizes shape change to achieve locomotion over both a flat and inclined surface. Modelling this robot in simulation, we explore its capabilities in two environments and demonstrate the existence of environment-specific shapes and gaits that successfully transfer to the physical hardware. We found that the shape-changing robot traverses these environments better than an equivalent but non-morphing robot, in simulation and reality.

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Fig. 1: Shape change can result in faster locomotion speeds than control adaptation, when a robot must operate in multiple environments.
Fig. 2: Simulation revealed successful shapes and controllers, which we attempted to realize in hardware.
Fig. 3: Automated search attempting to improve gaits in both environments.
Fig. 4: Shape change allowed the physical robot to operate in previously inaccessible environments.
Fig. 5: The variable-friction feet change their frictional properties when inflated.

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Data availability

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Code availability

A public repository at https://github.com/jpp46/NATURE_MI2020 contains the code necessary to reproduce the soft-robot simulations.

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Acknowledgements

This work was supported by NSF EFRI award 1830870. D.S.S. was supported by a NASA Space Technology Research Fellowship (80NSSC17K0164). J.P.P. was supported by the Vermont Space Grant Consortium under NASA Cooperative Agreement NNX15AP86H.

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Author notes

  1. These authors contributed equally: Dylan S. Shah, Joshua P. Powers.

Authors and Affiliations

  1. Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA

    Dylan S. Shah, Liana G. Tilton & Rebecca Kramer-Bottiglio

  2. Department of Computer Science, University of Vermont, Burlington, VT, USA

    Joshua P. Powers, Sam Kriegman & Josh Bongard

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Contributions

J.B., R.K.-B., S.K., D.S.S. and J.P.P. conceived the project and planned the experiments. J.P.P. coded the simulation and ran the evolutionary algorithm experiments. D.S.S. and L.G.T. manufactured the robot and performed the hardware experiments. D.S.S., J.P.P., L.G.T., S.K., J.B. and R.K.-B. drafted and edited the manuscript. All authors contributed to, and agree with, the content of the final version of the manuscript.

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Correspondence to Rebecca Kramer-Bottiglio.

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Supplementary Figs. 1–4 and Text 1.

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Supplementary Video 1

In this video, a multi-material robot simulator is used to design a shape-changing robot, which is then transferred to physical hardware. The simulated and real robots can use shape change to switch between rolling gaits and inchworm gaits, to locomote in multiple environments.

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Shah, D.S., Powers, J.P., Tilton, L.G. et al. A soft robot that adapts to environments through shape change. Nat Mach Intell 3, 51–59 (2021). https://doi.org/10.1038/s42256-020-00263-1

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