The Clever Vine-Like Robot That Grows and Steers With Air

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In a hallway of an engineering building at Stanford University, some devilish researchers have built a sprawling obstacle course. To make it through, competitors have to wind over sand, through a door, up some steps, and finally, through a forest of small pillars. Sounds like the Rube Goldbergian machinations of an grad student with too much time and Red Bull on their hands, but no: This is a robot training ground.

See, a tracked robot might be able to navigate the sand and the steps, but good luck in the forest. A wheeled automaton could well get stuck in the sand. Amateurs, says vinebot. Air pumps into a flexible plastic tube, slowly extending it over the sand as an operator steers it through the door and over the steps and between the pillars. Obstacles bested.

You may have seen vinebot snaking around last summer, but now it’s better than ever. What used to be a simple inflating plastic tube now comes complete with actuators—the bits that help any robot change direction. But this is not like any other robot. It’s part of the first generation of advanced “soft robots,” which promise to go where no traditional robot can tread—literally.

Vinebot got its name because, well, it grows like a vine. Air pushes plastic tubing through the center of more plastic tubing. “When you do that, the material comes out the top—it inverts, which basically means it turns inside out, and that way you get more material onto the tip,” says Stanford roboticist Allison Okamura, who developed the vinebot with fellow Stanford researchers Sean Follmer and Jonathan Fan, as well as Elliot Hawkes of UC Santa Barbara.

As long as it has a steady supply of air, vinebot grows. To shrink it, the operator simply reels the tubing back into a spool.

Running along the tube are a series of plastic bags, which change their length when inflated with air. “That allows us to create a kind of air-driven tendon which allows us to steer it and still has the entire robot remain soft so that we can grow it at the same time,” Okamura says.

The more primitive version of vinebot could only move forward—conforming to the twists and turns of a maze, for instance. But this upgraded version can move forward and move its head around to steer. Thus an operator can guide it through a door or between pillars.

And because it’s inflatable, vinebot can squeeze into those hard-to-reach places. “There’s a clear tradeoff between traditional robots that can be very robust and made of strong materials like metal, and the soft robots which might be more delicate but have more flexibility,” says Okamura.

Soft robots like this aren’t likely to replace those hulking manufacturing arms on a factory floor—traditional robots are just far stronger, and at this point more precise. But they may find work someday searching collapsed buildings. (Search and rescue, to be honest, is the far-off promise of a lot of robots. Carnegie Melon’s snake robot tried helping out after Mexico’s big September quake, but ended up not helping much at all.) And their squishy form factor will make them safer to use around human collaborators without, you know, crushing them.

Problems, though. To get vinebot moving right now, you’ve gotta have a heavy, bulky air compressor handy. And two, you run into issues with structural integrity. Plastic tubing isn’t the most robust of materials, so to survive in the wild, soft robots like vinebot will have to utilize newfangled materials that are both strong and flexible (vinebot’s people have been experimenting with nylon). Because all it takes is one nick to cripple the thing. So it’s a good thing roboticists are already experimenting with materials that heal when cut.

Think Terminator, only with more cuddles and less murder.

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