Wheelchair Mobility for the
Paralyzed
It took a long time to decide which
power wheelchair to get for
Jeff. Unless someone finds a cure, his entire active life will be spent in a
wheelchair, so the choice was important. There are some
marvelous chairs out there, looking very trim and very sharp and very high tech
and elegant. We decided
to get none of those.
Being a young man, with all of his old
appetites intact, Jeff decided to get a brute of a power chair that is
rare, not particularly pretty, but aggressive. It is the sports utility vehicle
of power chairs. No, it is more than that. It is the Humvee of powered
wheelchairs. It is the kind of chair
you would go over a cliff in.
It is called the
OmegaTrac.
|
 |
|
The Omega model
we should have ordered ? |
It will roll through potholes, it will
roll over rocks, it will roll over curbstones…and it will keep on rolling long
after it has hit a bump at speed and catapulted Jeffrey thirty feet in the
air. That’s why we strap him in.
The co-designer of the chair is a young
man named Jim Finch, who is a quadriplegic. He was
14 years old in 1978, when a drunk driver slammed into the Finch family car,
killing Jim’s younger brother, and breaking Jim’s neck. Dissatisfied with the
chairs that were on the market, Jim and his father Tom began designing a new
chair in 1990, and in 1995 they started the Teftec
Corporation and introduced their first chair.
Manufacturer site...
Teftec built its OmegaTrac with a true
automotive-style transmission, so the chair
tracks straight across even steeply inclined
surfaces. The suspension is independent at all four wheels; and Jeff’s model
came with air-adjustable shock absorbers that not only smooth the ride, but also
allow the front and back of the chair to be raised and lowered independently.
The drive wheels are massive, and all the components are overbuilt. An early
model of the chair that Teftec uses in their crash tests is still running, and
is still used as a sales demo at shows.
The Best Wheelchair in the
World?
There is no such thing. Any single
chair is judged by how it fits the needs of its particular rider, and no chair
is “best” for everyone. But take a look at the package we have put together for
Jeff -- which we think is the best chair in the world that is currently
available for him.
 The
chair is a technology platform. To the extent
possible, we pack onto the chair everything Jeff needs to survive, travel and to
interact with the world, as independently as possible
 Jeff
operates the chair with the primary joystick (2).
Using his lips and tongue, he can vary the direction and speed of the chair.
A sip-and-puff tube (1) is used
to switch between other functions: tilting the seat; raising and lowering the
front and rear shock absorbers; and turning the lights on or off. A
secondary joystick called a “QuadJoy” (3) operates
the chair’s laptop computer. The microphone (4) is
connected to the laptop computer, and also by wireless transmitter to the
desktop computer when Jeff is at home.
It takes less than a minute to attach
or detach Jeff’s computer system, using a simple mounting setup with one pin.
The computer is held in place on its “table” by heavy duty Velcro. Power is
taken from the chair’s 24 volt battery system and dropped through a RadioShack
converter to 16 volts.
 The
QuadJoy substitutes for a mouse. Jeff uses
one on his wheelchair and another on his desktop system. The QuadJoy uses a
sip-and-puff joystick wand to enable all the functions of a mouse, including
separate left and right button control. Until recently the device was
manufactured and sold by Tom Street, a quadriplegic.
Tragically, Tom passed away during the summer of 2001, and the business has been
handled since then by his mom and brother. They sell a terrific product.
An “electronics
door” hides and holds the brains of the microphone system and other
components. Hinged at the bottom and held by pins at the top, the door offers
easy access. A slide-off metal bracket on the door will quickly mount the
LTV ventilator, if Jeff is unable to use his
phrenic nerve pacer.
 The
electronics door in open position, showing how all of the electronic components
become available for service. The entire inner surface of the door is covered
with Velcro, so the components can be moved around or taken off.
A close-up of the inner door,
showing electronic
components including the microphone system: the
terminator from the model 853
microphone (2) by
Audio-Technica;
the STM-DA3 microphone distribution amplifier (3)
from Radio Design Labs,
that adds “phantom power” to the the microphone signal, then splits it out to
the laptop computer and to the
Lectrosonics
model M175
wireless transmitter (4); and the power supply block (1). The power
supply block is fed by a small rechargeable 12-volt battery that we use only for
the microphone system, to avoid “electrical noise” (from drive motors,
actuators, controllers, etc.) in the chair’s primary power circuit. Because the
microphone is used for voice recognition applications, we try to keep its signal
as clean as possible.
 The
chair with the LTV backup ventilator attached to the electronics door. It takes
less than two minutes to set up the vent and hoses. The vent will run
about 30-60 minutes on its internal battery, and we carry with it power
converters that will also run it off household current or the van battery. If
needed, we have a 12-hour battery in a removable battery box that quickly
attaches to the back of the chassis using stainless steel pins.
Jeff doing a
weight shift with the LTV ventilator attached. Everything fits! Any other
“portable” ventilator now on the market would be crushed by this maneuver.
Notice, by the way, that because the laptop computer is mounted to the seat
frame and not the chassis, the screen maintains its orientation and Jeff can use
the computer at any angle of tilt.
 Toe
guards. Although a wheelchair rider’s toes are the first things to hit a
corner, table, wall or hurrying restaurant waiter, we have never seen toe guards
of any kind in any catalog or at any trade show. These were made by cutting two
sets of normal plastic foot supports roughly in half, and using the backs of one
set to serve as the fronts of the combined set. Because Jeff has heavy duty toe
guards, he can use soft footwear instead of stiff, confining shoes, thereby
reducing the risk of pressure sores on his feet.
We scan all of Jeff’s reading materials
-- including textbooks, handouts,
and notes taken by others -- into multi-page tiff files,
then save them onto both his laptop and desktop computers. He brings his reading
material wherever he goes, and can follow along in class without assistance.
 The
wireless connection. Jeff’s laptop computer
connects to the Internet, to his desktop computer, and to the other computers on
our home network through a wireless access point. A
small card in his laptop computer links to the access point by radio waves, so
there is no need to hook Jeff up by a direct wire connection. Again, this is all
part of the effort to make him as independent as possible. He can transfer
information back and forth between computers using only his mouth-operated
laptop controls; and he can surf the net at high speed while watching TV, or
sitting on the backyard deck. The wireless equipment is made by
Linksys.
NOTE:
Reflect on the “communication technology” represented here -- especially the
portable wireless microphone system -- and you may learn three important
lessons: (a) most of the critical components are widely available right now; (b)
some of the important pieces -- like the wheelchair’s electronics door -- are
uncomplicated, and can be home-made out of cheap materials with simple tools and
minimal skills; and (c) many of the vital components are not offered in any
“assistive device” catalog, nor sold by any vendor catering specially to the
“disability market.”
In fact, we realized a
breakthrough in finding microphone technology that worked when we enlisted the
advice of Don Houde, a nearby specialist in the design of high fidelity sound
systems for home and commercial use. Walk into his store and you will see car
stereos, big-screen TVs, Hi-fi amps and speakers -- and
not a single wheelchair. He had no experience in helping
quadriplegics use voice recognition software. But he knew which devices
delivered sound signals faithfully.
If you buy a plastic battery box from
your local auto or boat parts dealer, it will cost you about $15 dollars. If you
buy the same box from a medical equipment supplier, it will cost you $50
dollars, maybe $100. If you buy a microphone from an assistive device dealer, it
probably won't work and will cost you a fortune. So go buy a great one from the
folks Celine Dion buys them from -- microphone dealers -- and save some
money. Remember: don’t wait for technology to be branded
“for the disabled.” Go out and look for it wherever your imagination
takes you.
|
