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Honda's U3-X unicycle really for robots

Experimental unicycle for human travel shows off development more applicable to mobile robots.

Candace Lombardi
In a software-driven world, it's easy to forget about the nuts and bolts. Whether it's cars, robots, personal gadgetry or industrial machines, Candace Lombardi examines the moving parts that keep our world rotating. A journalist who divides her time between the United States and the United Kingdom, Lombardi has written about technology for the sites of The New York Times, CNET, USA Today, MSN, ZDNet, Silicon.com, and GameSpot. She is a member of the CNET Blog Network and is not a current employee of CNET.
Candace Lombardi
3 min read

Honda on Wednesday unveiled the U3-X, a stool with a unique directional wheel system that allows it to travel diagonally, as well as right, left, forward, and backward.

It's basically a robotic unicycle.

The device is able to readjust itself so that instead of riders having to constantly balance themselves, the robotic unicycle does the compensating.

Honda pointed out in its unveiling video that the U3-X's seat is slightly higher than an average person's waistline, forcing riders to jump up slightly to sit on it and place their feet on a foot rest. This elevated height of the robotic unicycle leaves riders at relative eye level with passing pedestrians while in motion, according to Honda.

It's a nice touch. A common complaint among people in wheelchairs are the social and psychological effects of literally being looked down upon while traveling the world in a sitting position. But requiring the rider to be able to hold upright while on a backless seat clearly disqualifies the U3-X as a wheelchair substitute for many.

And in this age of rising obesity, who among the fitness-conscious is really going to ride the streets on a robotic stool when they can get a little chance at some exercise during their busy day by walking?

It's just one of those things you know no one is really going to buy. So why, then, did Honda unveil the U3-X robotic unicycle?

Like the Segway, the U3-X is more about showing off an engineering breakthrough than selling an actual product. In this case, Honda contributes to the ongoing discourse on mobility among roboticists.

The legs vs. wheels debate among roboticists has been going on for years. A third option, the tank tread system, has been introduced in recent years as a solution for rugged combat robots like iRobot's Packbot and Vecna Robotics' BEAR. Still others have looked to nature for locomotion ideas as with the SINTEF snake and the dolphin-like Seaglider.

Honda's HOT Drive System (Honda Omni Traction Drive System), the omni-directional wheel Honda claims is the "world's first wheel structure which enables movement in all directions" adds to this ongoing discourse on mobility.

Note Honda's word choice in describing their system.

The U3-X is not the first multi-directional rolling robot and Honda knows this. Carnegie Mellon, for example, unveiled the Ballbot in 2006. But the method Honda uses--which includes synchronizing small motor-controlled wheels to make the U3-X multi-directional--is unique.

Honda's U3-X also includes balance control technology that allows the device to respond to how its load shifts and readjust balance accordingly while on the go.

"The incline sensor detects the incline of the device based on the weight shift of the rider and determines the rider's intention in terms of the direction and speed. Based on the data, precise control is applied to return the device to an upright position, which achieves smooth and agile movements and simple operation by weight shift only," Honda said in a statement.

The device will be more fully demonstrated at the Tokyo Motor Show 2009 in October.