Inchworms inspire stretchy wormlike robots

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The movements of inchworms and earthworms have inspired the development of stretchy wormlike robots that have potential applications in industry and prosthetics.

Developed by engineers at Glasgow University, the wormlike robots can stretch up to nine times their own length and are capable of a form of proprioception, which is the method used by biological organisms to perceive their position in space. That ability allows the robot worms to squeeze into areas that conventionally rigid robots cannot reach.

According to Glasgow University, the researchers hope that their breakthrough could lead to a new generation of robots capable of autonomously exploring difficult-to-reach places. It is claimed they could find applications in mining, construction or even in disaster relief to search for survivors trapped in rubble.

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Their technology could also be used in developing more lifelike prosthetics, or equipping robots with the ability to wrap around and lift irregularly-shaped heavy objects.

The development builds on previous research from Glasgow University’s Bendable Electronics and Sensing Technologies (BEST) group, which embeds flexible electronics into deformable surfaces.

That expertise has allowed them to build intrinsic strain sensors into the wormlike robots, which are around 4.5cm long and covered in ‘skin’ made from Ecoflex and a graphite paste developed by the team.

Permanent magnets attached at either end of the robots’ tubular bodies help them to move along a metal surface. The sensors in their skin help them ‘sense’ their movements in relation to their bodies by measuring the electrical resistance of the graphite paste, which changes as the robots’ bodies expand.

wormlike robots
Glasgow's robots are capable of a form of proprioception (Inchworm image by Michelle Grewe from Pixabay)

When the resistance reaches a pre-set maximum value, the body contracts again, moving it forward. Professor Ravinder Dahiya of Glasgow University’s James Watt School of Engineering leads the BEST group, which developed the system.

“Proprioception is a vital characteristic of many forms of biological life, and scientists have long been inspired to try and develop engineered systems which mimic this ability,” he said in a statement. “Our bioinspired robots are a step towards creating soft, flexible robot systems capable of the infinite directions of movement that nature has created in inchworms and earthworms.

“The ability of soft robots like these to adapt to their surroundings through seamlessly embedded stretchable sensors could help autonomous robots more effectively navigate through even the most challenging environments.”

The team’s paper, titled ‘Bioinspired Inchworm and Earthworm like Soft Robots with Intrinsic Strain Sensing’, is published in Advanced Intelligent Systems. The research was supported by funding from EPSRC and the European Commission.