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You've Never Seen a Robot Drive System Like This Before

Using just a single spinning hemisphere mounted on a gimbal, this robot demonstrates some incredible agility

2 min read
You've Never Seen a Robot Drive System Like This Before

What you're looking here is a hemispherical omnidirectional gimbaled wheel, or HOG wheel. It's nothing more than a black rubber hemisphere that rotates like a spinning top, with servos that can tilt it left and right and forwards and backwards. Powered by this simple drive system, the robot that it's attached to can scoot around the floor in ways that I would have to characterize as "alarmingly fast."

Before I go on about the design, have a look at just what this thing is capable of. Its creator, Curtis Boirum, a grad student at Bradley University, in Peoria, Ill., demoed it at the 2011 RoboGames symposium:

Just to reiterate, a HOG wheel is simply a rubber hemisphere that spins on its axis very, very fast. When the hemisphere is vertical, it's just like a spinning top, but by tilting the hemisphere so that one of its sides makes contact with the ground, you can vector torque in any direction near-instantaneously, depending on which side of the hemisphere you use.

So for example, if the hemisphere is spinning clockwise, tilting it so that the right side contacts the ground will "pull" the robot forward, with the amount of torque directly proportional to the tilt of the hemisphere, like an infinite gear ratio without any gears. It's very simple, very efficient, and as you can see from the video, the drive system is capable of delivering more torque than any of the poor robots that it's attached to can reliably handle.

This idea has actually been around for decades: a concept illustration of a car with a HOG drive graced the cover of the 1938 edition of Mechanics and Handicraft Magazine. Nothing much has really been done with it since, but Curtis (who actually re-invented the system from scratch) is hoping to create a cheap, powerful, and agile omnidirectional drive system that can be adapted for use by both researchers and hobbyists. We hope he'll build a car-sized version too.

Update: This is now being called a "Singularity Drive System," in reference to the zero gear ratio transition point, which is a mathematical singularity.

[ Bradley University ]

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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
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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
DarkGray

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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