For robots to be useful for real-world applications, they must be safe around humans, be adaptable to their environment, and operate in an untethered manner. Soft robots could potentially meet these requirements; however, existing soft robotic architectures are limited by their ability to scale to human sizes and operate at these scales without a tether to transmit power or pressurized air from an external source. In this project, we have developed an untethered, inflated robotic truss, composed of thin-walled inflatable tubes, capable of shape change by continuously relocating its joints, while its total edge length remains constant. A set of identical roller modules each pinch the tube to create an effective joint that separates two edges, and modules can be connected to form complex structures. Driving a roller module along a tube changes the overall shape, lengthening one edge and shortening another, while the total edge length and hence fluid volume remain constant. This isoperimetric behavior allows the robot to operate without compressing air or requiring a tether. Our concept brings together advantages from three distinct types of robots—soft, collective, and truss-based—while overcoming certain limitations of each. Our robots are robust and safe, like soft robots, but not limited by a tether; are modular, like collective robots, but not limited by complex subunits; and are shape-changing, like truss robots, but not limited by rigid linear actuators. With the same collective of robots we can construct a variety of truss structures including two-dimensional (2D) robots capable of shape change and a human-scale 3D robot capable of punctuated rolling locomotion and manipulation.
- N. S. Usevitch*, Z. M. Hammond*, M. Schwager, A. M. Okamura, E. W. Hawkes+, S. Follmer+, An untethered isoperimetric soft robot. Sci. Robot. 4, eaaz0492 (2020). DOI: 10.1126/scirobotics.aaz0492
*,+ These authors contributed equally.
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- And more
1 Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.
2 Department of Aeronautics and Astronautics, Stanford University, Stanford, CA, USA.
3 Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, CA, USA.
Funding: S.F., A.M.O., E.W.H., and Z.M.H. acknowledge support from the NSF under grant no. 1637446. M.S. and N.S.U. acknowledge support from DARPA YFA under grant no. D18AP00064. M.S., S.F., E.W.H., Z.M.H., and N.S.U. acknowledge support from the NSF under grant no. 1925030. E.W.H. acknowledges support under NSF grant no. 1925373.