Co.Design

Robot "Hand" Made of Coffee Grounds and a Balloon Picks Up Almost Anything

Why bother with expensive artificial fingers when a vacuum-powered beanbag works better?

Robots are great at manipulating objects like automobile parts and circuit-board components. But what about a glass of orange juice, a ball bearing, or a raw egg? Expensive, Terminator-style artificial hands are awful at picking up everyday objects that they're not pre-programmed to recognize, so if robots are ever going to reliably help out around the house—or perform unpredictable missions in space or war zones—they'll need to be able to get a grip on anything.

The best solution? A beanbag filled with coffee grounds, according to these researchers. "It basically works on the same mechanics as when coffee shops vacuum-seal packs of ground espresso," Heinrich Jaeger, a lead researcher on the project, tells Co.Design. "It needs no special sensors to compute how much pressure to apply—the materials of the gripper just do it automatically." Come again?

A team of engineers and scientists from the University of Chicago, Cornell University, and iRobot built this prototype gripper, which uses a clever combination of friction, suction, and clever low-tech design to reliably snag almost anything it encounters. The "hand" is nothing more than a stretchable bag filled with lightweight "granular materials" (such as coffee grounds in the demo video above, although salt, sugar, or glass beads also work) attached to a vacuum pump.

A robot arm presses the bag onto the object to be gripped, forcing the grains inside the bag to perfectly conform to the object's surface. Then the vacuum sucks the excess air out of the bag, packing the grains tightly together around the object's contours, forming a perfect seal.

The beanbag grains go through what's called a "jamming transition," in which physical pressure makes the tiny particles lock together and unlock again on demand. (That's why the robot can also put the raw egg back down after picking it up.) The jamming transition doesn't require special materials—"even M&Ms could work," says Jaeger—and the passive grip can be strong enough to lift a shotput or gentle enough to cradle a light bulb.

Their prototype "hand" is only 10 centimeters in diameter, but Jaeger speculates that a 1-meter-wide model "could lift pretty much anything that wasn't made of lead"—like, say, collapsed beams after an earthquake. Take that, Terminator!

[Read more at Cornell Computational Synthesis Laboratory]

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