In the world of robotics, researchers are going soft – in their designs at least. Soft robots have some advantages over their more rigid brethren but till now, they've not been able to do much other than wriggle around. An advance from UC San Diego has changed that by creating a bot with a firm body and soft legs that can wander over difficult ground like sand or pebbles.

Soft robots hold promise because, unlike bots that are made from hard plastics and metal, they can bump into things – including humans – and not cause any damage. This makes them ideal for use in factories, hospitals or even at home as companion robots. Soft robots are also good at squishing through tough spaces and getting around in water, so they could be used as investigators in factories or repair bots for city infrastructure.

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But before soft robots become more of a reality, they'll need better locomotion skills. So far we've seen a chemically powered octopus-based bot that can wiggle its arms, a nearly invisible underwater robot that can catch and release fish, and wriggly caterpillar-like soft bot that uses light to move. But none of these can really get around all that well on solid ground. The UCSD robot, which incorporates a mix of hard and soft robotics inspired by nature changes that, leading the researchers to claim that it's the first robot with soft legs that can navigate difficult terrain.

"Previous work (PDF) has used molding techniques to make relatively simple soft actuated leg designs that use air pressure to bend in one direction and use elastic energy stored in the limbs to return to the original shape," Dylan Drotman, told New Atlas. Drotman is a Ph.D. student at the Jacobs School of Engineering at UC San Diego who led the effort to design the legs and the robot's control systems.

"The result is a robot that mostly shuffles its feet along the ground," he added. "Our new soft quadruped is capable of lifting its limbs, allowing it to clear obstacles, which has not been done before. We achieved this using multi-material 3D printing to rapidly fabricate complex 3D designs."

The high-end Connex 3 3D printer was used to create the bot, especially its game-changing soft legs.

"We focused on the design of soft actuated legs to achieve the complex motions needed to navigate over rough terrain," Drotman told us. "Walking on land is a challenge for soft organisms, which is why the octopus prefers to move in water. Similarly, for robots, there is a trade-off between the 'softness' of the body and its ability to apply forces or lift its weight against gravity. In this work, we chose to focus on completely soft legs, which adapt to terrain and can squeeze through tight spaces."

The legs, which are attached to the rigid body in a "X" configuration, feature a series of hollow chambers that were 3D-printed from a rubbery material. As they chambers are inflated, the legs move. Timing, pressure and the order in which the chambers are inflated all play into how the bot walks and had to be precisely calculated. The robot can walk at speeds of up to 20 mm (.8 in) per second. Right now the robot is still connected to a series of tubes, an air pump and an open-source circuit board, but the researchers are working to miniaturize the components so the bot can walk untethered.

They will present their work at the IEEE International Conference on Robotics and Automation from May 29 to June 3 in Singapore. The video below shows the robot in action.

Source: UC San Diego

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