2000 Conference Proceedings
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An Internet-Based, Force-Feedback Rehabilitation System for
Arm Movement after Brain Injury
David Reinkensmeyer, Chris Painter, Stanley Yang, Erin
Abbey, Brian Kaino
Department of Mechanical and Aerospace Engineering
Center for Biomedical Engineering
4200 Engineering Gateway
University of California, Irvine, 92697-3975
We describe a computer-based system for providing arm
movement therapy to people with brain injury. The system uses a
force feedback joystick to apply therapeutic patterns of force
to the arm as the user plays video games.It operates over the
Internet using Java, and can track user movement recovery over
time and report it to a remote location.The system can also be
customized to provide a personalized program of therapeutic
exercise.Initial use of the system by three individuals with
stroke is reported.
In the U.S. each year, over 400,000 people lose strength,
coordination, and sensation in the arm and hand due to stroke
or traumatic brain injury. With practice, however, they often
improve their ability to reach, grasp, and manipulate objects.
Significant improvements are possible even several years after
brain injury . Physical and occupational therapy are an
essential part of recovery, and typically include hands-on
manipulations, such as manually assisting in desired arm
movements.These manipulations are designed to increase sensory
input and stimulate regeneration in the nervous system. Sensory
motor skills improve with increasing levels of therapy .
Unfortunately, because of economic pressures on the U.S.
health care system, individuals with a brain injury are going
home sooner and getting less hands-on therapy. Compounding the
problem, there is a current lack of technology available for
practicing self-therapy at home. To address these needs,
several research groups, including our own, are developing
robotic devices that physically interact with people to
stimulate the senses of touch and movement, and to retrain
coordinated movement [3,4]. While preliminary clinical trials
are promising for both improved evaluation [5-7] and therapy
[8,9], key practical problems with these devices are their cost
and size, which may ultimately limit their accessibility and
practicality, especially for home use.
The advent of dynamic force feedback technology for the PC,
coupled with the networking power of the Internet, could solve
these problems. Commercial force feedback joysticks designed
primarily for gaming applications can not only sense a
person’s movement, but can also apply forces during
movement. Like existing robotic therapy devices, such devices
could be used to stimulate the sense of touch and movement, and
could apply therapeutic patterns of forces to the hand and arm
as the user attempts to move. Unlike larger robotic devices,
however, force feedback joysticks could become truly accessible
personal movement trainers because they are already in mass
production and can be purchased at low cost. By networking them
to rehabilitation centers through the Internet, such devices
could provide a means for an individual with a brain injury to
access a personalized program of therapeutic exercises,
customized by a rehabilitation expert. Also, networking could
provide a means for the rehabilitation expert to track the
user's sensory motor performance while the user stays at home.
Force feedback movement therapy could thus become a viable
aspect of telerehabilitation services .
This paper describes the design and initial testing of an
Internet-based, force-feedback physical rehabilitation system
for training and assessing arm movement after brain injury. The
mechanical and software design of the system are described
first. Then, initial use of the system by three individuals
with stroke is reported. In conclusion, future development of
the system is described.
The Microsoft Sidewinder Force Feedback Pro Joystick was used
as the force feedback platform for this project. The joystick
required two mechanical modifications in order to make it
usable by individuals with a brain injury:
Handle Re-Design: Many individuals with brain injury lose
dexterity of the fingers, making grasping difficult. Although
the Microsoft handle is ergonomically designed, individuals
with brain injury have difficulty in securely grasping it. To
address this problem, a new handle was designed that clips on
to the preexisting handle. The initial step in creating the new
handle design was to survey seven individuals with a brain
injury to determine the criteria for a basic shape that would
comfortably hold the hand. Many prefabricated splints, made out
of plastics that can be molded when heated, are available for
brain-injured people with spastic hands. Four of these splints
(conical, U-shaped, ball, anti-spasticity) were tested by seven
individuals with brain injury to determine the best splint with
regard to comfort and accessibility. The volunteers who were
surveyed agreed that the splint with a small conical radius
grip, and the splint with a U-shaped grip were the most
comfortable and the easiest to hold. It was determined that by
slightly modifying the U-shaped splint it could be made to mate
securely with the joystick handle without using fasteners, and
it was thus possible to simply clip it on to the joystick. A
Velcro strap was added over the back of the hand to help keep
the hand engaged to the splint. The resulting design (see
figure 1 below) holds the hand comfortably and securely, and
allows users with one impaired hand to place their impaired
hand in the handle using their unimpaired hand. A similar
clip-on handle was designed for the left hand, making the
joystick usable by individuals with impairment on either side.
Arm Support System: The Microsoft Sidewinder Force Feedback
Pro Joystick can exert a peak force of approximately 1 Kg,
which is not enough to move the arm against gravity. A
commercially available articulating armrest was thus integrated
into the system (Ergorest, Oscar Dellert AB, Finland). The
armrest, which was designed to support the arm during computer
keyboard usage, consists of a forearm tray connected to a
low-friction, three-joint mechanical linkage. It allows the
forearm to be positioned and oriented arbitrarily in the
horizontal plane and is height adjustable.
To hold the joystick and armrest, a wood base with a cutout in
the shape of the joystick base was made, and a protruding wood
beam was attached to the base for clamping the arm support at
the appropriate height. To use the system, the wood base is
clamped to a table, the joystick is placed inside the cutout to
keep it from slipping, and the armrest is adjusted to support
the user's arm (see Figure 2 below).
The resulting system allows comfortable movement of the hand
in a workspace of approximately six by six centimeters in the
Design Philosophy: Two approaches to the software design were
considered. The first was to develop a stand-alone program that
could be installed on a PC, to control the joystick and to
transfer information through a temporary network connection.
The second approach was to incorporate force feedback into a
web page using a Java applet, and to use the web page to
transfer desired information. The second approach was chosen
for two reasons. First, since Java applets are downloaded onto
the host computer each time a web page is accessed, new
versions of the therapy program could in effect be
automatically installed each time a user accessed the therapy
web page. This was attractive not only for facilitating rapid
modifications during the early development of the system, but
also eventually for providing a means for personalization of
therapy plans.In effect, Java therapy applets designed at a
remote center for each user could be downloaded "on the fly".
The second advantage was the platform independence of Java.
Using any Java-enabled web browser, users on a variety of
computing platforms, with a variety of input devices, could
access the therapy program, running it on their own processor.
It should be noted, however, that device and platform
independent standards for force feedback have to our knowledge
not yet been implemented, and thus the force feedback system
described here works currently only with the Microsoft joystick
on a PC using Internet Explorer.
In order to control the joystick through a Java applet, we
used FEELtheWEB software developed by Immersion Corporation.
FEELtheWEB is an ActiveX control for Internet Explorer that can
apply forces to the joystick and receive function calls through
Prototype Therapy Game: A prototype therapy game with force
feedback was developed to test the system. The user begins by
logging into the system home page using a personal username and
password. The user is then taken to a therapy page that
downloads a Java applet containing the therapy game onto his or
her computer. In the therapy game, the user is asked to move a
circular cursor into a square target with the joystick as
quickly and accurately as possible. After a delay, if the user
has not yet moved into the target, the motors on the joystick
activate and assist the hand in moving into the target. This
continues for a predetermined number of attempts with the
target changing positions to span a 360-degree range of
movement directions. For each attempt, the game tracks and
records a variety of movement parameters, including the initial
and final joystick position, the time when the joystick forces
turned on, the total time to complete the trial, and the
distance (in pixels) the cursor moved before and after the
forces were activated. Upon completion of the game, the data is
posted to the server computer.
Three people with hemiparesis resulting from stroke tested the
joystick system at a local outpatient rehabilitation center.The
Institutional Review Board of UCI gave approval for the
experiments, and the subjects provided informed consent.
Subjects 1, 2, and 3 were aged 53, 32, and 52, and were 5, 2,
and 4 years post-stroke respectively. They had different levels
of arm impairment, classifiable respectively as mild, moderate,
and severe according to a clinical scale. The subjects played a
modified version of the therapy game, moving the circle cursor
into the target squares in a series of ninety-six trials, with
joystick forces assisting for half the trials and deactivated
for the other half.The delay between presentation of a new
target and activation of force feedback was set to 0.5 seconds
in the assisted trials.
It was found that the forces helped the subjects move more
quickly into the target, with the greatest improvement shown
for the most impaired subject (see Figure 3 below). These
results demonstrate that the joystick system is strong and
accurate enough to assist in moving impaired arms.
The same three subjects are currently using the system several
times a week to practice arm movement.By analyzing data posted
to our server, changes in the subjects’ movement ability
with time can be tracked (see Figure 4 below).
The subjects have used the system to practice hundreds of
movements over three weeks, although it is too early to draw
conclusions about the efficacy of the therapy.
Discussion and Future Directions
The force feedback therapy system described in this paper has
several advantages: It is ergonomic for individuals with a
brain injury. It does not require ability to grasp, and an
individual with a one-sided impairment can attach his or her
hand to it without assistance. It is strong and accurate enough
to assist in moving impaired arms to desired locations,
provided the arm is supported in an armrest. It is inexpensive.
The joystick and arm support currently retail for around $100.
Robotic systems that could achieve similar functionality
currently cost tens of thousands of dollars. It can track user
movement recovery over time, storing performance data on a
remote server. Its software is rapidly modifiable and
customizable. Its software is structured to be platform
independent (currently for non force-feedback pointing devices,
and in the future, for force feedback devices). Software
Development Plans: Software is currently being developed to
display online measures of the user's movement performance as a
function of movement practice. This software will allow users
to self-monitor movement recovery. For example, a person who
has just suffered a stroke, and has been released from the
hospital, will be able to logon daily from home, practice
moving, and determine if his or her arm movement ability has
changed. In addition, this capability will ultimately allow
remotely located rehabilitation professionals to evaluate
users' progress and to make therapy recommendations. Force
feedback is also being incorporated into other games besides
the simple prototype game described in this paper. A wide range
of freeware Java games are available on the Internet, such as
card games, sports simulations, and arcade-style games. A
selection of these games is being modified to include force
feedback that physically assists in playing the game.Other
force-enabled games targeted at training specific deficits in
sensory motor performance common after brain injury are also
Future Directions: Several key questions for future
To what extent does practicing therapy with the system improve
arm movement ability? The system described here provides a
powerful new tool for identifying the relationship between
movement therapy and recovery. It is hoped that the system can
be distributed to a large number of users, and that this
relationship can be characterized for different types of brain
injuries at different times post injury. What are the optimal
movement therapy techniques? Our initial efforts have focused
on using force feedback to assist in movement. However, it is
unclear whether such assistance, as opposed to movement
practice without assistance or, alternately, with resistance,
is the optimal therapy technique. The joystick system provides
a means to test what therapy techniques work best for which
Can the system be applied to rehabilitation of other user
populations? With appropriately designed software, people with
cerebral palsy, spinal cord injury, Parkinson's disease,
orthopedic injuries, and cognitive impairments may also benefit
from the Internet-based, force feedback therapy.
The authors gratefully acknowledge the support of the Microsoft
Foundation, through a New Discoveries Grant, and the assistance
of Richard Grauman and the staff and clients of the
Rehabilitation Institute of Southern California.
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