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Robo-Air Blower Makes Ping-Pong Balls, Apples Defy Gravity

Why use a mechanical gripper to manipulate objects when you can use... air?

2 min read

You might have seen this demo in a classroom or science museum: a jet of compressed air keeps a ball floating above the ground, seemingly defying gravity. Now a pair of grad students at the University of Illinois at Urbana-Champaign have taken the trick to the next level. The result will blow your socks off.

Aaron Becker and Robert Sandheinrich, with help from professor Timothy Bretl, built a computer-controlled air jet system that can make spherical objects like ping-pong balls not only float in place but also move along complex trajectories -- even performing some acrobatic maneuvers like passing through wire loops. Their robotic air blower can also sort balls of different weights and precisely propel balls toward a target. And it can lift an apple and non-spherical objects like a water bottle. Did we mention it works great as a high-speed onion peeler?

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The system consists of a gimbaled air jet with two degrees of freedom. The air jet is supplied up to 620 kPa through a DC motor-controlled valve. Stereo vision cameras track the objects, and a control algorithm uses the position data and a fluid dynamics model to adjust the air jet, varying its speed and direction to keep the object in equilibrium.

Making a plastic ball "levitate" using compressed air is an old trick (the fast moving air creates a low pressure zone around the ball that traps it), but the UIUC guys had to solve a number of hurdles in engineering their system. The design of the control system, in particular, was a big challenge because the dynamics of the air flow can exhibit chaotic behavior, which is hard to model, and also because adding more than one ball changes the flow field in complex ways. Still, the system can manipulate spheres of various sizes (12 to 97 mm in radius and 2.6 to 188 g in mass).

Now, what would you do with such a thing? The students, who presented their work at this year's IEEE/RSJ International Conference on Intelligent Robots and Systems [full paper here], say that non-contact manipulation with an air jet could be used in applications that involve sorting small parts or handling flexible, delicate objects such as clothes, paper, and sliced fruit. Whether or not industry will adopt their invention, one thing is certain: they had a lot of fun building it.

Video: Aaron Becker and Robert Sandheinrich

The Conversation (0)

The Bionic-Hand Arms Race

The prosthetics industry is too focused on high-tech limbs that are complicated, costly, and often impractical

12 min read
A photograph of a young woman with brown eyes and neck length hair dyed rose gold sits at a white table. In one hand she holds a carbon fiber robotic arm and hand. Her other arm ends near her elbow. Her short sleeve shirt has a pattern on it of illustrated hands.

The author, Britt Young, holding her Ottobock bebionic bionic arm.

Gabriela Hasbun. Makeup: Maria Nguyen for MAC cosmetics; Hair: Joan Laqui for Living Proof

In Jules Verne’s 1865 novel From the Earth to the Moon, members of the fictitious Baltimore Gun Club, all disabled Civil War veterans, restlessly search for a new enemy to conquer. They had spent the war innovating new, deadlier weaponry. By the war’s end, with “not quite one arm between four persons, and exactly two legs between six,” these self-taught amputee-weaponsmiths decide to repurpose their skills toward a new projectile: a rocket ship.

The story of the Baltimore Gun Club propelling themselves to the moon is about the extraordinary masculine power of the veteran, who doesn’t simply “overcome” his disability; he derives power and ambition from it. Their “crutches, wooden legs, artificial arms, steel hooks, caoutchouc [rubber] jaws, silver craniums [and] platinum noses” don’t play leading roles in their personalities—they are merely tools on their bodies. These piecemeal men are unlikely crusaders of invention with an even more unlikely mission. And yet who better to design the next great leap in technology than men remade by technology themselves?

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