Scientists create 3D-printed, four-legged robot that can walk on sand and pebbles

The first 3D-printed four-legged robot has been developed by scientists that can climb over obstacles and walk on different rough surfaces such as sand and pebbles.

Researchers led by Michael Tolley, a professor at the University of California San Diego, used a high-end 3D-printer to make soft and rigid materials together within the same components.

This made it possible to design more complex shapes for the robot's legs.

Bringing together soft and rigid materials will help create a new generation of fast, agile robots that are more adaptable and can safely work side by side with humans, said Tolley.

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The idea of blending soft and hard materials into the robot's body came from nature, he added.

"In nature, complexity has a very low cost. Using new manufacturing techniques like 3D printing, we're trying to translate this to robotics", Tolley said.

Printing soft and rigid robots rather than relying on molds to manufacture them is much cheaper and faster, Tolley said.

So far, soft robots have only been able to shuffle or crawl on the ground without being able to lift their legs. This robot is actually able to walk, researchers said.

They successfully tested the tethered robot on large rocks, inclined surfaces and sand. The robot also was able to transition from walking to crawling into an increasingly confined space, much like a cat wiggling into a crawl space.

Dylan Drotman, a PhD student at UC San Diego, led the effort to design the legs and the robot's control systems.

He also developed models to predict how the robot would move, which he then compared to how the robot actually behaved in a real-life environment.

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The legs are made up of three parallel, connected sealed inflatable chambers, or actuators, 3D-printed from a rubber-like material. The chambers are hollow on the inside, so they can be inflated.

On the outside, the chambers are bellowed, which allows engineers to better control the legs' movements. For example, when one chamber is inflated and the other two aren't, the legbends. The legs are laid out in the shape of an X and connected to a rigid body.

The robot's gait depends on the order of the timing, the amount of pressure and the order in which the pistons in its four legs are inflated.