Soft, squishy robots can change shape, size

Tufts University developing squeezable robots

Toss aside your typical idea of a robot -- all metal, jerky movements and a stiff-legged walk.

Scientists at Tufts University are developing soft, squishy robots that are able to squeeze into spaces a fraction of their normal size and then morph back into their original size and shape. And they plan on replacing the synthetic materials used to make them with biological materials so the robots would be biodegradable, too.

Creating soft robots would mean a whole new way of looking at robotics, according to , the Henry Bromfield Pearson Professor of Natural Sciences at Tufts and co-principal investigator on the project.

"Most machines are made out of stiff materials," he said. "They're great if you want to move things around because you can make joints and hinges and wheels. A lot of animals, though, don't have hard parts — like bones or skeletons. We suddenly realized that these things can control their bodies without them but there was no theory on how soft things can be controlled and moved.... We want to learn from the animal how to do that and how to engineer that."

Using biological materials like silk proteins to make muscles and sensory organs, the robots could be used for landmine detection and search-and-rescue efforts in hazardous conditions. They could also carry miniature versions of themselves to access even smaller areas. In a military capacity, for instance, soldiers could release them into a building where the only access is a crack under a door or a conduit for an electrical cable, with the soft robots able to maneuver over craggy debris that would trip up traditional robots, or climb ropes, cables or trees.

"We hope our technology will help us create more adaptable robots that can manage in different situations," said Trimmer. "Robots might be good working in a building or on a road but they're generally not good at walking in the woods or climbing trees or walls.... They'd be like an octopus that can change its shape into anything. A large octopus can compress itself down to the size of its eyeball. We have no idea how to do that yet, but this project is trying to understand the technology that is needed to do that."

And to develop the technology needed to build squishy robots, Trimmer and his fellow scientists are looking to, well, squishy creatures in nature such as the octopus and the caterpillar.

Researchers have spent a lot of time studying the caterpillar because — even without bones or joints — it can control its body with a relatively simple nervous system. Part of the genius behind the caterpillar is that with no joints and only two muscles controlling each leg, it largely can move itself around because of the way its body responds to the muscles simply contracting and releasing in the legs.

"We imagine that the way the material bends and the way it responds to forces is part of the computation of the movement," said Trimmer. "The way things swing would make it work properly."

And to control those movements, Trimmer said researchers are working on creating a tiny, flexible computer chip. "The idea is that instead of having a supercomputer to control these very complicated soft structures, we think you can build the computation into the material and the structure," he explained. "If you look at a soft-bodied animal, in a traditional engineering approach, you'd expect to use more computation to control it. It should have a bigger brain but you don't see that. There's not that much difference between the brain in the soft caterpillar and the moth or butterfly it becomes which has a skeleton. It doesn't need a supercomputer."

Trimmer noted that the new robots could be used in health care, giving doctors a soft device to use for endoscopies, for example, instead of semi-rigid surgical devices that could damage human tissue and cause the patient pain.

Prototypes have already been built that are as small as 2 grams and as large as 200 grams.

To continue Tufts' soft robot development, the U.S. Defense Advanced Research Projects Agency (DARPA) gave the school a US$3.3 million contract last week.

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