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A soft robot that adapts to environments through shape change

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 simulate, design 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 automated discovery 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 discovered increasingly successful gaits in both environments.
Fig. 4: Optimal orientation and pressure found in simulation, as a function of the angle of incline.
Fig. 5: Shape change allowed the physical robot to operate in previously inaccessible environments.
Fig. 6: The variable-friction feet change their frictional properties when inflated.

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://doi.org/10.5281/zenodo.4067077 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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Authors

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.

Corresponding author

Correspondence to Rebecca Kramer-Bottiglio.

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The authors declare no competing interests.

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Peer review information Nature Machine Intelligence thanks the anonymous reviewers for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–4 and Text 1.

Reporting Summary

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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