Introduction“It” was a design engineering project shrouded in a veil

of mystery. A cryptic posting made to the Web site

Inside.com sparked a wild amount of anticipation and

speculation about “It.”

Rumors spread throughout the engineering communi-

ty that the project designated by the moniker “Ginger,”

would be one of the most significant advances in trans-

portation technology ever devised. Different reports

identified the device as everything from a hydrogen-

powered hovercraft to a magnetic antigravity device to

a matter transporter right out of “Star Trek.”

As it happened,

“Ginger” emerged as

the Segway Human

Transporter (HT), a

two-wheeled, self-pro-

pelled scooter some-

what reminiscent in

appearance to an old-

style push mower.

I n v e n t e d b y

Manches t e r, N .H .

(U.S.A.) entrepreneur

Dean Kamen, the

Segway HT is posited

to have the same impact

on personal transporta-

tion as when the auto-

mobile replaced the

horse and buggy.

At the heart of the Segway HT is a complex bundle of

gyros and sensors that imitate the human body’s abili-

ty to maintain balance – a process billed as “dynamic

stabilization.” While the Segway HT possesses no

engine, throttle, gearshift or steering wheel, it can

transport the average rider for a full day, non-stop, on

little more than a nickel’s worth of electricity. The

Segway HT’s sensors detect the subtle weight shifts

made by an operator’s body when walking and

respond by moving the device in the appropriate

direction.

The National Highway Traffic Safety Administration

has already ruled that it does not consider the Segway

HT a vehicle, thus freeing it from the operating

restrictions — and necessary operator’s licenses — of

cars and motorcycles. It is Kamen’s goal to see the

device become a common site on urban sidewalks

throughout the world.

ChallengeThe Segway HT packs a multitude of hardware and

software components into a disconcertingly small

space. “It’s a bit like packing eight pounds worth of

stuff into a five-pound bag,” quips Mike Martin, head

of the Mechanical Integrity group at what is now

known as Segway LLC.

One of the responsibilities of Martin’s group is to

ensure that the features and functionality designed

into the Segway HT conform to specified perform-

ance criteria. The group works closely with Segway’s

Design & Release team of design engineers, perform-

ing structural, thermal and noise/vibration/harshness

(NVH) analyses on everything from components and

sub-assemblies to full assemblies.

Very often, the Pro/ENGINEER files that emerged

out of the Design & Release group were composed of

odd geometric configurations that rendered standard

mechanical analysis techniques ineffective or

extremely difficult to conduct. In particular, the

Segway HT’s chassis presented the Mechanical

Integrity group with a number of simulation chal-

lenges.

The chassis was to be constructed to accommodate

the weight of an operator up to 250 pounds, while

simultaneously acting as housing for the device’s

motors, batteries and electronic components.

Naturally, the chassis had to be strong enough to meet

these standards while being lightweight at the same

time.

EXECUTIVE SUMMARY

Challenge:Calculate performance of multi-

functional components, with non-

linear designs, on unique self-pro-

pelled scooter

Solution:Analyze designed components and

assemblies in ANSYS Multiphysics

Benefits: Easily able to accommodate

Segway HT’s large and complex

design issues

Successfully predicted areas of

stress and fatigue on numerous

components

Instrumental in design of propri-

etary physical fatigue-testing

machine

Creating “Empowered Pedestrians” with ANSYS MultiphysicsS E G W A Y L L C

CASE STUDY

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“ANSYS Multiphysics is limited only by the performance of the hardware

on which it is installed,” Mike Martin, Segway LLC.

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A specific area of concern arose at the interface

between the control shaft and the chassis

(below). Not only was this base designed to

attach the device’s handlebar control shaft to

the chassis, it would also be engineered to

house the machine’s electrical

re-charge unit. These specifi-

cations lead the Design &

Release group to render a design which

“is full o f ‘ s w o o p y ’ c u r v e s , ”

as Martin himself puts it.

Consequently, there was no way to

predict its performance using simple pen-

cil-and-paper calculations.

SolutionBefore Dean Kamen split the Segway operation off

into an independent corporation, it was part of his

DEKA Research and Development Company. Under

the auspices of DEKA, many other innovative prod-

ucts were brought to light, including the heart stent

used by U.S. Vice President Dick Cheney (covered

in ANSYS Case Study Engineered to Save Lives:

DEKA Redesigns Medical Stent Using ANSYS

Software) and iBOT, a 4-wheel drive, motorized

wheelchair with — among other features — the

ability to actually climb stairs.

ANSYS Multiphysics software was instrumental in

realizing these ideas at DEKA. Consequently, it was

once again utilized to assist the Mechanical

Integrity group in analyzing the geometric nonlin-

earities present in the various design elements of the

Segway HT’s chassis.

“Since there are no straight lines in the design of the

control shaft base,” observes Mike Martin, “there

was no other way to get a good handle on its design

performance.” He also notes the software’s ability to

quickly mesh and analyze large-scale geometries as

being key to resolving the most intricate design

issues. “In many other packages you have to work

beginning of its design cycle. However, he does pre-

dict its influence manifesting in the numerous

Segway accessories yet to be developed, such as a

series of device-mounted bags. “ANSYS

Multiphysics is limited only by the performance

qualities of the hardware on which it is installed,”

he enthuses.

Indeed, as Mark Wyer points out, ANSYS

Multiphysics also played a prominent role in the

design of the proprietary fatigue-testing machine

utilized by the Mechanical Integrity group. “This

helped us to ensure that the machine wouldn’t wear

out before the components we tested did,” he

observes.

While it may be true that the Segway HT won’t turn

lead into gold or transport you to another world,

(“Sue me,” jokes Dean Kamen) it nonetheless has

the potential to change the face of the urban land-

scape.

Presently, the scooter is being tested as an alterna-

tive mode of transportation for rangers at the

National Parks Service and ambassadors in the city

of Atlanta, Ga. (U.S.A.). Big-name companies such

as General Electric and Michelin are also using it as

a means of getting around.

Perhaps the most significant push for the use of the

Segway thus far came in June, 2002. United States

Postmaster General John Potter then announced

that the Postal Service had purchased 40 of the

devices. Although the Postal Service had already

tested Segway HTs on routes in the Tampa, Fla. and

Concord, N.H. (U.S.A.) areas, Potter said that the

Service would expand its test into six other loca-

tions throughout the country.

Consumers will also be able to purchase a version

of the device beginning sometime in 2003.

the mesh so much. With ANSYS Multiphysics, you

just throw the model in and, with maybe only a

couple of bumps and tweaks, you get a good

mesh.”

Mark Wyer, also an analyst with the Segway

Mechanical Integrity group, points out the

usefulness of ANSYS Multiphysics

in the stress and fatigue analyses

of the Segway HT’s numerous

components and assemblies.

“Because the Segway has a number of sudden

geometry changes,” he says, “the potential for high

stress levels exists.”

Wyer used ANSYS Multiphysics to predict the loca-

tion of stress/fatigue “hot spots” on numerous areas

of the Segway HT. For instance, on the wheel model

(shown below), ANSYS Multiphysics accurately

predicted the load conditions the Segway’s wheels

would see in regular usage. These predictions were

verified via physical tests on a specially designed

fatigue-testing machine the team developed.

BenefitsMike Martin anticipates no major changes to the

Segway HT’s current configuration, a fact he attrib-

utes to the use of ANSYS Multiphysics from the

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All Rights Reserved.

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CASE STUDY

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Early on, the Segway HT was purported to be everything from a hydrogen-

powered hovercraft to a matter transporter right out of “Star Trek.”