The Technology Behind IT

ByPaul Eng

Dec. 4, 2001 -- IT may look like a two-wheeled scooter, but how Dean Kamen's recently unveiled moving machine works relies on technology more closely associated with flying.

"You stand on this Segway Human Transporter and you think forward and then you go forward," inventor Kamen said Monday on ABCNEWS' Good Morning America. "If you think backward, you go backward."

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Magic? To some degree, perhaps. And while Kamen and officials at Segway are still a bit reluctant to describe exactly how IT works, some of Segway's internal workings are rooted in some standard technology, albeit refined to a high level.

According to company documents, a key component in Segway's ability to balance on two-wheels is in a sensor package developed by Silicon Sensing Systems in Plymouth, England. Inside the package are tiny gyroscopes — the same devices typically found in navigation systems for planes, boats, and spacecraft.

Steady as She Goes

A gyroscope is an instrument with a tiny spinning wheel which keeps the device balanced and constantly pointed in the direction of the spinning wheel's axis. Try and push at the tip of a rapidly spinning toy top, for example, and in most cases, the top just glides across in the direction of the push rather than topple over.

This resistance to change is why gyros have been typically used in so-called inertial navigation systems. Spinning a gyro — say pointing to the Earth's magnetic North Pole — will help the navigator of a ship or plane determine how far his or her craft has deviated from the desired direction.

Marshall Brain, an author and founder of HowStuffWorks, Inc., believes that the Segway uses the same principal. "Take three gyros and electronics and you can sense movement in any direction," he says. But, more than just sensing a change in direction, Brain says "IT's taking signals from [the sensors] and deciding what is happening to the vehicle and deciding what to do."

Sensing a Change

Although Kamen and his company won't disclose the actual workings of Segway, reports in Time magazine indicate that as many as 10 microprocessors are used to decide how to react to the signals from the sensors.

For example, if a rider leans forward on a motionless Segway, the gyro sensors will pick up the shift in the vehicle's stance and send electric signals to the onboard computer. The computer would then decide that the rider wishes to go forward and power the scooter's two motors appropriately. If the rider leans back, the computer reverses the motors to stop the forward motion.

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Brain, who has not been on a Segway, notes that while gyro sensors have been around for ages, it is the hardware and software that makes the Segway truly unique. "We're just getting to the point where we have enough computing power that it can mimic what humans can do," he says.

Smart Keys

The Segway also embodies other high-tech features as well.

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Each Segway, for example, will come with a set of electronic "keys." Each key is unique to each scooter, allowing only the appropriate owner to operate the vehicle. Moreover, each key can set the Segway's performance characteristic, such as limiting the traveling speed.

While the technology behind the futuristic vehicle may seem far-fetched, inventor Kamen says the Segway won't be. He says that the company currently plans to supply outfits such as the U.S. Postal Service and the National Parks Service with initial units for tests and evaluations.

But ordinary consumers may be able to test drive a version sometime next year. The expected cost: $3,000.