Momenteel is de uitgebreide technische beschrijven van de Segway
alleen nog maar in het Engels beschikbaar. Na de vertaling zullen
wij de Nederlandse versie toevoegen.
The Science behind the Segway
Balance Sensor Assembly (BSA)
BSA, supplied by Silicon Sensing Systems, is an elegantly designed,
extremely robust, and yet incredibly sensitive piece of equipment.
This small cube, 3 inches on a side, is packed with five
solid-state, vibrating-ring, angular-rate sensors ("gyroscopes")
that use the Coriolis effect to measure rotation speed. These tiny
rings are electromechanically vibrated in such a way that when they
are rotated, a small force is generated that can be detected in the
internal electronics of the sensor. Each "gyro" is placed at a
unique angle that allows it to measure multiple directions. Segway's
onboard computers constantly compare the data from all five gyros to
determine if any of the five is supplying faulty data--in this
condition, it can compensate and use data from the remaining sensors
to continue balancing through a controlled safety shutdown. Two tilt
sensors filled with an electrolyte fluid provide a gravity reference
in the same way your inner ear does for your own sense of balance.
The BSA is monitored by two independent microprocessors and is split
into two independent halves for redundancy. Even the communication
between sides is performed optically to avoid electrical faults on
one side propagating to the other.
Segway HT's motors are unique in a number of respects. Produced by
Pacific Scientific, a division of Danaher, they are the
highest-power motors for their size and weight ever put into mass
production. Each motor is capable of maintaining a power output of
1.5 kilowatts--that's 2 horsepower!
The motors use brushless servo technology, meaning there are no
contacts to wear, arc, and reduce performance. The magnets are
constructed of an incredibly powerful rare-earth material:
neodymium-iron-boron. Each motor is constructed with two independent
sets of windings, each driven by a separate board and motor. Under
normal conditions, both sets of windings work in parallel, sharing
the load. In the event of a failure, the motor is designed to
instantly disable the faulty side and use the remaining winding to
maintain control of the Segway HT until it can be brought to a stop.
The motor is carefully balanced to operate up to 8,000 rpm, allowing
it to produce very high power levels in a small package. Feedback
from the motor back to the Segway HT is provided by redundant,
noncontact analog hall sensors that sense the positions of magnets
with no moving parts other than the motor shaft itself.
Segway HT's gearbox, a joint effort between Axicon Technologies and
Segway, is constructed more like a precision Swiss watch than a
traditional gear drive from an automobile. A two-stage reduction
system provides a 24:1 reduction, allowing the motor to operate at
powerful, efficient speeds throughout the full range of speeds of
the Segway HT. Each gear is cut to a helical profile, which creates
a spiral engagement to minimize noise and increase the load
capability of the gears. The number of teeth on each gear is chosen
to produce noninteger gear ratios. This means that the teeth will
mesh in a different location each revolution, maximizing the life of
the gearbox. Our engineers were so obsessed with the details on the
Segway HT that they designed the meshes in the gearbox to produce
sound exactly two musical octaves apart--when the Segway HT moves,
it makes music, not noise.
The gearbox is pre-assembled and lubricated, and is designed to
require no maintenance over the life of the Segway HT. It has been
tested for thousands of miles under severe conditions.
Wheel and Tire
was one of the earliest partners in the Segway HT design project.
The tires on the Segway HT have been designed specifically for this
product, using a unique tread compound (a silica-based compound
instead of traditional carbon-based materials), giving enhanced
traction and minimized marking on indoor floors, and a specially
engineered tubeless construction that allows low pressure for
comfort and traction while minimizing rolling resistance for long
The tire is mounted on an equally unique wheel design: the wheel is
constructed of a sophisticated engineering-grade thermoplastic
chosen in partnership with GE Plastics. This composite material
allows light weight and excellent durability, and actually reduces
noise transmitted from the drive system. The wheel is molded around
a forged steel hub, eliminating fasteners that can loosen over time.
The attachment between this hub and the transmissions incorporates a
unique (patent pending) taper and hex design, which allows a single
nut to attach or remove the wheel while retaining the security of
multiple-bolt systems more typically seen in conventional
Segway HT uses twin NiMH battery packs, designed in partnership with
SAFT (a division of Alcatel), running at a nominal 72 volts. These
nickel-metal hydride cells deliver the highest power of any
currently available chemistry, optimized to maintain the Segway HT's
balance under severe conditions. These are not your cell phone
Each pack consists of an array of high-capacity cells and a
custom-designed circuit board that constantly monitors the
temperature and voltage of the pack in multiple locations. This
assembly is enclosed in another unique application of GE
thermoplastics--the battery box is sealed using a vibration welding
technique that makes the outside of the pack a single, continuous
structure--sealed from moisture and strong enough to survive the
most extreme tests our durability engineers could throw at it.
The internal electronics in the battery incorporate "smart"
charging--the customer need only plug the Segway HT into the wall
and the battery will choose the appropriate charge rate based on
temperature, voltage, and level of charge. The batteries will quick
charge, then automatically transition into a balance and maintenance
charge mode. The Segway HT customer does not need to worry about
memory or timing their charges--just plug it in.
Under normal operation, the Segway HT carefully monitors both
batteries and automatically adjusts to drain the batteries evenly.
In the unlikely event of a battery failure, the system is designed
to use the second battery to operate the machine and allow it to
continue balancing until it is brought to a safe stop.
sophisticated controller boards from Delphi Electronics provide both
brains and brawn for the system. Delphi Electronics was chosen as a
partner based on their track record in the production of
high-volume, high-quality automotive electronics for such demanding
applications as airbag modules.
Each board contains a Texas Instruments digital signal processor,
monitoring the entire Segway HT system and checking 100 times per
second for any faults or conditions that might require immediate
response. It reads the information from the BSA to determine if the
rider is leaning forward or backward, and instantly uses this
information to deliver power from the batteries to the motors
through a set of 12 high-power, high-voltage field-effect
transistors (FETs). These calculations take place 100 times a
second, and the motors are adjusted at up to 1,000 times per second,
responding far more quickly than the human body is capable of
perceiving. Although each board is capable of operating the Segway
HT after a failure (each board, in fact, powers electrical circuits
on both motors), under normal conditions they share the load.
dictionary defines segue as "a smooth transition from one place or
idea to another." While the Segway HT represents a smooth transition
from one physical place to another, we chose the name Segway for our
company because we believe the Segway HT also represents an
important transition to a new idea: an energy efficient,
environmentally friendly, productivity enhancing, and fun
alternative for short distance travel.