What is the Segway all about
The Segway® Personal Transporter (PT) or just
Segway for short, is designed to go anywhere you go. With
a Segway, you can commute, shop, and run errands
more quickly while enjoying an eco-friendly ride
like nothing you've ever experienced. With no need
for petrol, easy battery charging and operating
costs of only cents per day, you too will discover
the Segway smile!
The Segway requires no special skills - it takes care of the balancing-
on-two-wheels part - and virtually anyone can use one. It's compact, yet
powerful and easily rechargeable from any power point. The Segway will
change the way you think about transportation.
But the Segway isn't just about fun transportation. It also makes businesses
more productive by allowing workers greater visibility, versatility, mobility
and carrying capacity. It does it all by harnessing some of the most advanced,
thoroughly-tested technology ever created.
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, yet it manages to stay
upright by itself.
To move forward or backward on the Segway, the rider just leans slightly
forward or backward. To turn left or right, the rider simply moves the LeanSteer
frame left or right.
The ability to balance on its own 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 and gyroscopic 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. Segway calls this behaviour
dynamic stabilization and has patented
the unique process that allows the Segway to balance on just two wheels.
 The Segway is controlled by an intelligent network of sensors, mechanical
assemblies, propulsion, and control systems. The second you step on, five
micro-machined gyroscopic sensors and two accelerometers sense the changing
terrain and your body position at 100 times per second – faster than the brain
can think.
Segways use a special solid-state angular rate sensor constructed using
silicon. This type of gyroscopic sensor determines an object's rotation using
the Coriolis effect on a very small scale.
Simply put, the Coriolis effect is the apparent turning of a moving object in
relation to another rotating object. For example, an airplane trying to travel
in a straight line can appear to turn because the Earth is rotating underneath
it.
The Segway has five gyroscopic sensors, though it only needs three to
detect leaning forward or backward (termed “pitch”), leaning to the left or
right (termed "roll") and steering to the left or right (termed “yaw”). The
extra sensors add redundancy, to make the product more reliable. All of this
leaning and steering information, as well as information from additional tilt
sensors, is passed on to the brain of the device.
The brains and brawn are made up of two identical and redundant sets of
microprocessor-based electronic controller circuit boards, batteries and motor
windings that operate together and share the load of driving the wheels. The
Segway has a number of additional onboard microprocessors. The vehicle requires
this much brain power because it needs to quickly make precise adjustments to
keep from falling over. If one controller board breaks down, the other set will
take over all functions.
The microprocessors run an advanced piece of software that controls the
Segway. This program monitors all of the stability information coming from the
gyroscopic sensors and adjusts the speed of the electric motors in response to
this information. The electric motors, which are powered by a pair of
rechargeable lithium-ion batteries, can turn each of the wheels independently at
variable speeds.
When the Segway leans forward, the motors drive both wheels forward to keep it
from tilting over. When the Segway leans backward, the motors drive both wheels
backward. When the rider moves the LeanSteer frame to turn left or right, the
motors drive one wheel faster than the other, or if travelling slowly enough,
drive the wheels in opposite directions, so that the Segway rotates (steers).
When under way, the Segway will generate precisely the right radius of turn so
that your lean is balanced by the centripetal acceleration generated by the
turn.
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