The 3D-printed robot with a hard heart and soft body

The design offers a new solution to an engineering challenge that has plagued soft robotics for years: the integration of rigid and soft materials.

Compared to their traditional counterparts, soft robots are better adapted to unstructured environments, more capable of squeezing into tight spaces, and safer for use in interactions with humans. In his lab at the Jacobs School of Engineering at UC San Diego, he borrows ideas from nature to design robots composed of soft materials; robots made by folding; and robots that self-assemble. OK, perhaps we aren’t quite at that point yet, but researchers at the University of California, San Diego and Harvard University have created a 3D printed robot that has the ability to jump six times its own height, and even more impressive is the fact that it can do so over and over again without suffering a malfunction.

Harvard engineers have done that, developing one of the first soft robots through 3-D printing that moves autonomously.

“I think the takeaway is that 3D printing, right now, opens up a whole new fabrication strategy for soft robotics”, Bartlett says.

So the scientists decided to build a faster robot with hard and soft elements – and they chose to make a jumping robot. Then butane and oxygen are mixed and ignited, catapulting the robot into the air.

To initiate movement, the robot inflates its pneumatic legs to tilt its body in the direction it wants to go.

So why such a odd design? “But for practical reasons, our soft robots typically have some rigid components – things like batteries and control electronics”. The ignition of these gases results in the bottom layer of the robot ballooning outwards to provide the necessary propulsion to lift the device off the ground and the variable stiffness of the top layer allows it to land safely. That simple setup makes the jumper a breeze to fabricate. It also hops. Inside the robot’s core, a small, controlled explosion powers each leap. The top hemisphere is like a half shell, 3D-printed in once piece, with nine different layers of stiffness, creating a structure that goes from rubber-like flexibility on the exterior to full rigidity near to core. This expands the flexible bottom of the robot, propelling it into the air. And unlike the entirely soft version, it wouldn’t simply transfer the force of a fall to the robot’s delicate, inflexible components.

Tolley said the inspiration for blending soft and hard materials came from nature.

Bartlett’s robot was inspired by another combustion-powered, soft jumper created by Robert Shepherd, a roboticist at Cornell University, back in 2012. “Using new manufacturing techniques like 3D printing, we’re trying to translate this to robotics”.

Take a closer look at the robot jumping in this short high-speed video.

“It’s sort of well-known in material science that if you have a very rigid thing connected to a very soft thing, you get stress concentrations at that interface, and that can lead to all sorts of problems”, Tolley said. “That’s a big deal, because when something that previously required an expensive process is suddenly accessible to a large amount of interested people, you can expect huge improvements in the technology”, he says.