Soft-bodied robot can walk through fire

US researchers have built a crawling soft-bodied robot that can operate without a tether and survive fire, snow and being run over by a car.

The cross-shaped quadruped robot built by engineers at Harvard University uses chambers of compressed air to move along the ground, carrying its control system and power supply on its back.

It is a scaled-up and more mobile version of earlier designs that could aid the development of machines that can better survive harsh environments but also pose less risk to humans operating alongside such devices.

‘One of the things that limit our imagination is that factory robots are very large and scary and dangerous to be around,’ said Michael Tolley, first author of a paper on the work published in Soft Robotics.

‘As a lay person, you can’t just walk into a factory where industrial robots are working. But a soft system is inherently less dangerous, so you can start to interact with it more, and I think that opens up many more opportunities.’

Previous versions of such soft robots were typically no larger than a note pad but the new device is more than 50cm in length and can carry over 3kg of weight on its back, enabling it to operate without a tether to a control and power system.

‘Earlier versions of soft robots were all tethered, which works fine in some applications, but what we wanted to do was challenge people’s concept of what a robot has to look like,’

‘We think the reason people have settled on using metal and rigid materials for robots is because they’re easier to model and control. This work is very inspired by nature, and we wanted to demonstrate that soft materials can also be the basis for robots.’

The robot is made from a composite silicone rubber impregnated with hollow glass microspheres with an underside of Kevlar for added toughness. This created a lightweight structure that was strong enough for the increased air pressure inside its pneumatic movement system needed to carry the increased weight on the robot’s back.

‘As soon as you start thinking about putting the basic components you need to make this work — micro-compressors, controllers, and batteries — on an untethered robot, you need a design that can carry those parts,’ said Tolley.

‘You need to think about something that can handle much higher pressures, so there are materials challenges and there are design challenges and there are control challenges.’

The researchers tested the robot in snow, submerged it in water, walked it through flames, and even ran it over with a car, without causing significant damage.