As most everyone predicted, the mysterious IT project (aka Ginger) turned out to be a compact transportation machine, with room for one standing rider.


Photo courtesy Segway, LLC
At first glance, this device (called the SegwayTM Human Transporter) doesn't seem all that remarkable -- it looks like a high-tech scooter. But people who have tried it out claim that it is much, much more -- a completely different way to get around.

Dean Kamen, the machine's inventor, has especially high hopes for the Segway. In an interview with Time Magazine, he claimed that his machine "will be to the car what the car was to the horse and buggy."

Now, we'll find out what sets the Segway apart from earlier vehicles, and we'll see why its inventor Dean Kamen thinks it will change the world. While it may not live up to the year of hype preceding its release, the Segway is most definitely an amazing machine.

"Weebles Wobble, But They Won't Fall Down"
When Dean Kamen unveiled the Segway on ABC's Good Morning America, he described the machine as "the world's first self-balancing human transporter." When you look at the machine in motion, you get an idea of what he's talking about. Unlike a car, the Segway only has two wheels -- it looks something like an ordinary hand truck -- yet it manages to stay upright by itself.


Photo courtesy Segway, LLC
Segways will come in a range of sizes (and prices).

To move forward or backward on the Segway, the rider just leans slightly forward or backward. To turn left or right, the rider turns the right handlebar forward or backward. But no matter what the rider does, the thing won't tip over. Since it responds to the slightest leaning motion, the Segway moves almost effortlessly -- it's a lot like walking.

This balancing act is the most amazing thing about the Segway, and it is the key to its operation. To understand how this system works, it helps to consider Kamen's model for the device -- the human body.

If you stand up and lean forward, so that you are out of balance, you probably won't fall on your face. Your brain knows you are out of balance, because fluid in your inner ear shifts, so it triggers you to put your leg forward and stop the fall. If you keep leaning forward, your brain will keep putting your legs forward to keep you upright. Instead of falling, you walk forward, one step at a time.

The Segway does pretty much the same thing, except it has wheels instead of legs, a motor instead of muscles, a collection of microprocessors instead of a brain and a set of sophisticated tilt sensors instead of an inner-ear balancing system. Like your brain, the Segway knows when you are leaning forward. To maintain balance, it turns the wheels at just the right speed, so you move forward.

In the next section, we'll take a closer look at the components that make this possible.

The Brains and the Brawn
At its most basic, the Segway is a combination of a series of sensors, a control system and a motor system. In this section, we'll look at each of these elements.


Photo courtesy Segway, LLC
The Segway consists of four major elements: the wheel and motor assembly, the sensor system, the circuit board brain and the operator control system.

According to Segway LLC, the primary sensor system is an assembly of gyroscopes. A basic gyroscope is a spinning wheel inside a stable frame. A spinning object resists changes to its axis of rotation, because an applied force moves along with the object itself. If you push on a point at the top of a spinning wheel, for example, that point moves around to the front of the wheel while it is still feeling the force you applied. As the point of force keeps moving, it ends up applying force on opposite ends of the wheel -- the force balances itself out. (See How Gyroscopes Work to learn more).

Because of its resistance to outside force, a gyroscope wheel will maintain its position in space (relative to the ground), even if you tilt it. But the gyroscope's frame will move freely in space. By measuring the position of the gyroscope's spinning wheel relative to the frame, a precise sensor can tell the pitch of an object (how much it is tilting away from an upright position) as well as its pitch rate (how quickly it is tilting).

A conventional gyroscope would be cumbersome and difficult to maintain in this sort of vehicle, so the Segway gets the same effect with a different sort of mechanism. Segways use a special solid-state angular rate sensor constructed using silicon. This sort of gyroscope determines an object's rotation using the Coriolis effect on a very small scale.

Simply put, the Coriolis effect is the apparent turning of an object moving in relation to another rotating object. For example, an airplane traveling in a straight line appears to turn because the Earth is rotating underneath it.

A typical solid-state silicon gyroscope consists of a tiny silicon plate mounted on a support frame. The silicon particles are moved by an electrostatic current applied across the plate. The particles move in a particular way, which causes the plate to vibrate in a predictable manner. But when the plate is rotated around its axis (that is, when the Segway rotates in that particular plane), the particles suddenly shift in relation to the plate. This alters the vibration, and the change is in proportion to the degree of rotation. The gyroscope system measures the change in vibration, and passes this information on to the computer. In this way, the computer can figure out when the Segway is rotating along particular axes. (Check out this site for more information on solid-state silicon gyroscopes).

The Segway has five gyroscopic sensors, though it only needs three to detect forward and backward pitch as well as leaning to the left or right (termed "roll"). The extra sensors make the vehicle more reliable. All of the tilt information, as well as information from additional tilt sensors, is passed on to the brain of the vehicle. The brain is made up of two electronic controller circuit boards, comprising a cluster of microprocessors. Time Magazine reports that the Segway has 10 onboard microprocessors, which boast, in total, about three times the power of a typical PC. The vehicle requires this much brain power because it needs to make extremely precise adjustments to keep from falling over. If one board breaks down, the other will take over all functions so that the vehicle stays upright.

The microprocessors run an advanced piece of software that controls the vehicle. This program monitors all of the stability information coming from the gyroscopic sensors and adjusts the speed of several electric motors in response to this information. The electric motors, which are powered by a pair of rechargeable nickel cadmium (NiCd) or nickel metal hydride (NIMH) batteries, can turn each of the wheels independently at variable speeds.

When the vehicle leans forward, the motors spin both wheels forward to keep from tilting over. When the vehicle leans backward, the motors spin both wheels backward. When the rider operates the handlebar control to turn left or right, the motors spin one wheel faster than the other, or spin the wheels in opposite directions, so that the vehicle rotates. The control system will also turn the vehicle when it senses too much roll to the left or right.

When a rider steps onto the Segway, weight sensors act as a switch to turn the vehicle on. If the rider stands still, the control program will only turn the wheels enough to balance the leaning force of gravity. The vehicle always stands upright, as if by magic.

This is certainly an amazing machine, but is it really as important as the Internet, as some have claimed? In the next section, we'll see what sort of impact this machine might have on the modern world.

Check Out My New Ride
At this point, nobody knows exactly what impact the Segway will have on the world. Kamen admits that the machine can never completely replace the car, because it doesn't have near the same capabilities. It only goes about 12 miles per hour, and it has to be hooked up to household electrical current for about six hours to store up enough juice for a 15-mile journey. Obviously, this sort of machine wouldn't do you much good on a cross-country road trip.

But Kamen does believe the Segway is a superior option for getting around a city. Cars take up a lot of room, so as soon as you have a bunch of people driving in a constrained area (like a city street), you get heavy traffic jams. It's also a hassle to park cars, and they are very expensive to maintain. All in all, a car is not an optimal machine for short trips in a crowded area.

The Segway is only slightly larger than a person, so it does not cause as much congestion as a car. Most likely, government regulations will authorize it as a sidewalk vehicle, so commuters will be able to zip through crowds, skipping the roadways completely. Just like scooters and bicycles, the vehicles would most likely be involved in a good number of pedestrian accidents. But the Segway's supporters say it's only about as dangerous as walking, since the vehicle moves at relatively slow speeds.

If the vehicle is as successful as Kamen hopes, cities will construct special Segway paths. Many critics suggest this is highly unlikely, noting that there just isn't room in more crowded cities for a new form of transportation.

While it won't get people to their destinations at top speeds, the Segway will probably zip by slow-moving, bumper-to-bumper traffic. Once they get to their destination, riders can carry their Segways inside with them without worrying about parking. And there's no need to stop by the gas station, as the vehicle runs on ordinary household electricity.

Segways are also good machines for getting around crowded warehouses, where tight corridors make it difficult to use bulkier vehicles. People may find them useful for getting around large pedestrian areas, such as airports or amusements parks. There is really no limit to how people might use the vehicle. The Segway can fit in most places you might walk, but it will get you there faster, and you won't exert much energy.

The question is: Will people be willing to shell out the $3,000 to $8,000 for the new machines, or will they keep using their feet, cars and bicycles? Kamen believes a lot of people will want the machine, after they are familiar with it and see what it is capable of. To this end, he is initially targeting government agencies and large corporations, not the consumer market. The U.S. Postal Service, the National Park Service, General Electric and other organizations have signed on to field test the vehicles over the next year. By the time Kamen launches the consumer model in late 2002 or early 2003, he hopes the Segway will have already established itself as an indispensable machine.

In the next section, we'll run down the Segway product specifications. For more articles about the Segway, check out the links page.

Segway Specs

For more information about the Segway, as well as its creator, check out the links on the next page!

Lots More Information!

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