A baby learning to walk takes her first steps toward
the waiting arms of her parents, who are watching
carefully to make sure she doesn't fall.  Children
learning to ride bicycles start out with training
wheels.  Student drivers practice in dual-control cars,
or on driving simulators.  People learning how to pilot
motorized wheelchairs, however, do not have a safe and
stress-free environment to learn in.  If you ask
physical rehabilitation therapists how they teach
patients to use wheelchair controls, you will be told
that they put the patient into a chair, turn it on, and
let the pilot "crash into walls until they get the hang
of it".
That is what I was told, by a physical therapist I was
interviewing.  She then asked if I could come up with a
better solution -- one that would be less frustrating
for a patient already undergoing a very frustrating
rehabilitation process (motorized wheelchairs are
usually used by stroke victims, or accident victims
with spinal cord injuries).  This is what inspired me
to propose this project: an inexpensive, PC-based,
"flight-simulator" for motorized wheelchairs.


For the past year, I have been working in the Newman
Lab as part of the Manus project, an ongoing project to
develop a robotic system for physical therapy.  The
Manus device is a computer-driven robot "arm" that
emulates the movements a physical therapist might make
while working with a patient to re-develop arm and hand
coordination.  The robot arm holds the patient's own
hand and arm, and either manipulates them according to
a pre-set program, or records the patient's own
movements for later analysis.  There are several
potential advantages in using this device.  One
advantage is the ability to use the patient's movements
to drive a graphical goal and feedback system on a
computer screen (In laymen's terms, a "video game").
As a student with background in both Cognitive Science
and Graphic Design, it has been my job on the project
to design and implement these games.  The response to
them from physical therapists has been extraordinarily

In the course of the Manus project, I have had the
opportunity to interview several physical therapists,
and to become somewhat familiar with the environment
they work in.  As I said in my introduction, the idea
for my project came from one of these therapists.  The
Flight Simulator could therefore be considered an
offshoot of the Manus project.  The focus of that
project, the Manus robot arm, will not be necessary for
the "flight simulator", however.  The flight simulator
will consist of a translator box (described below) and
another set of specifically designed video games.

Industry Support, Existing Products

In the course of researching the feasibility of this
project, I have spoken to representatives of the
country's two major wheelchair manufacturers.
My first industry contact was with Everest & Jennings,
the wheelchair company that supplies most of
Massachusetts' rehabilitation facilities.  My contacts
at Everest & Jennings were very enthusiastic about the
proposed flight simulator.  A technical support
engineer at that company has already provided me with
technical specifications for their wheelchair
controllers and control input devices, and has offered
to give me used equipment with which to build a
prototype (a typical wheel chair controller - the
"brains" of the chair - costs about $2,500 new.  A
control input device, such as a joystick, costs about
$250).  He has also offered to answer technical
questions as they arise.

My second industry contact was with Invacare.  This
company is now marketing a computerized training system
for wheelchairs on a limited basis.  Invacare's system
consists of a stationary dedicated wheelchair connected
to a dedicated PC.  The system lets the patient use the
chair control input device to "move" through a driver's
eye view of "real-life" situations.  According to my
contact at that company, this product, which is
considered extremely expensive, is "not a huge seller."
It is of interest, he said, only to high-level
quadriplegics with substantial health insurance.
(high-level quadriplegics do not have the use of their
hands, and typically control wheelchairs using some
form of mouth control).  For most patients, he said,
the therapists prefer to teach wheelchair control by
trial and error (i.e., letting them crash into walls).

Through my interviews with physical therapists, I have
come to believe that the failure of Invacare's system
is not due to dis-interest on the part of physical
therapists, but rather to the high cost and limited
appeal of their product.  I also believe that providing
a driver's eye view of the scene to be navigated is
inappropriate for this application.  Unless the system
can also provide the appropriate vestibular and
physical/inertial stimulation to the driver, the
driver's eye view feature will ultimately cause more
transition problems than it solves.  I prefer to use my
video games to teach basic control device operation (a
substantial issue for sip-stick or headband users), and
to let users become familiar with wheelchair driving
issues such as "wall jamming" (it's impossible to turn
a wheelchair that has run forward into a wall.  The
user must first back it up a couple of feet).

From the technical discussions I have already had with
the engineer at Everest & Jennings, I believe that it
will be possible to create a prototype of the simulator
within three months.

Description (and Technology)

The simulator system I envision will consist of the


1 -- An inexpensive translator box that will link the
output from the patient's own wheelchair control device
to a joystick port on a PC.  According to the technical
support engineer at Everest & Jennings with whom I have
discussed the project, the I/O for a standard motorized
wheelchair joystick is similar to the I/O for a
computer joystick (DC, low voltage).  He agrees that
the slight voltage change necessary could be performed
"on the fly" using appropriate hardware.  My goal for
the prototype will be to create a simple piece of
hardware that can perform the translation.  This will
be the only specialized hardware necessary to run the

2 -- An ordinary PC.  Many physical therapists already
use simple PC games for rehabilitation exercises.  The
games already available are typically mouse-driven
"connect the dots" type games that help develop
eye-hand coordination.  It would not be necessary for a
rehabilitation facility to purchase a dedicated PC in
order to use my system.

3 -- A joystick port card.  These can be added to any
IBM-compatible PC for less than $50.

4 -- The patient's own wheelchair control device.
According to my industry contacts, the control device
is a modular unit that can be detached from the
wheelchair controller.  There are several kinds of
control devices: "sip-stick" controls for high level
quadriplegics, controls based on head bands for people
who can move their necks, joysticks, etc.  For the
prototype, the wheelchair control device will be of the
joystick type.  It is my hope, however, that the system
will be flexible enough to eventually be used with any
kind of control device.

One module of the software will be a controller
emulator, that will allow the games to be used at
different levels of joystick sensitivity.  Chair
controllers are programmed to respond differently for
different users.  This module will emulate that
programming, and may be of use to physical therapists
in deciding how to program chairs for individual

The main module of the software will be a suite of
video games.  This project has a lot of potential for
creating different kinds of games, of varying
difficulty levels.  Because many of the users of this
system will be mentally intact (if physically
challenged), at least some of the games should be
intellectually interesting.  In addition, the games
should incorporate varying levels of difficulty, so
that even the weakest users can feel they are
"succeeding" (difficulty can be increased as mastery
increases).  I will have to do some more interviewing
with physical therapists before I finalize my software
designs, but some of the basic games I envision are as

1 - A "doodling" game.  This game will draw a cursor on
an otherwise blank screen.  Input from the control
device will move the cursor.  As a long time computer
user, I know that being able to "just play" with new
equipment is a very effective way to get a feel for its
operation.  This game probably wont' be used for very
long by any one patient, but I think using it will
increase the psychological comfort level of most people
in the process of learning to use a motorized chair.  I
also think it may be a useful tool for physical
therapists in determining the readiness of patients to
begin wheelchair training.

2 - A maze game.  This game will present a variety of
mazes on the screen, which the patient will have to
navigate through.  The cursor in this game should
exhibit standard wheelchair "quirks" such as wall
jamming, wide turning radius and wide undercarriage -
some of the paths in the maze that appear clear will
actually be inaccessible because they are too narrow or
require too sharp a turn.

3 - A "Donkey Kong" type game.  This game will be
similar to the maze game, but will show the cursor and
obstacles from an edge-on perspective.  Patients will
learn to avoid ramps that are too steep, and will be
penalized for going off curbs that do not have curb

(If all this sounds frustrating, consider trying to do
it the for the first time in a real-life situation,
with no reset button.).

Below is a rough estimate of my expenses for the project:
Living expenses		$2,500
Hardware for translator box	 	   500
C++ developers kit	 	   500
Long distance phone calls and fax/fedex	 	   200
Rental of a motorized wheel chair	
	(I plan to drive one around for a week,
	so I can discover more driving issues)	   500
Computer upgrade (bigger hard disk, math 
	co-processor, better screen) or partial 
	purchase price of new computer	   800

The Wheelchair Flight Simulator
Proposed by Amy Gorin
P.O. Box 11, Somerville MA, 02144
Course 2A, Class of 1994