May 24, 2005 —
A 50-year-old female stroke survivor, wearing stereoscopic
goggles, clutches the handle of a stylus like a pen and twists her
wrist to move a small ball through a maze-like tube on her computer
screen. She feels resistance in her hand, and sees the ball turn
colors, when she bumps against the side of the tube.
|
A
researcher holds a robotic force-feed device, called a PHANToM, to move
balls around in a virtual environment without bumping into other booby
traps on the screen. |
To avoid another collision, she tightens her grasp on the
force-feedback stylus, carefully rotates her right wrist, and pushes
the ball through the tube. A menu bar at the top of the screen displays
her scores, revealing how much time and force was exerted to complete
the task.
Another stroke survivor, an 80-year-old man, holds a ball the size
of an apricot in his impaired left hand, which he rotates in this
virtual environment in order to place one set of blocks on top of
another set. He doesn’t “feel” the blocks touch each other, but
his wrist movements are being tracked and precisely measured. The
measurements will help his physical therapist gauge the difficulty
level of his next therapy session.
Stroke patients like these, who face months of tedious
rehabilitation to recover function in affected limbs, are benefiting
from the rise of haptics technologies – interfaces that add the sense
of touch to virtual computer environments. Like computer games, virtual
therapeutic environments can be vastly more entertaining than
traditional rehabilitation and custom-designed to target specific motor
skills in each patient, like grasping, squeezing, pushing and rotating
the wrist.
|
Younbo
Jung, left, reaches out to touch objects in a virtual environment he
sees in his goggles, while fellow researcher Shih-Ching Yeh, right,
steadies the cable connection. |
Pinch, Grasp, Stroke and Squeeze
You’ll find most of the fun stuff going on in a high-tech
laboratory inside the USC Viterbi School of Engineering’s Integrated Media
Systems Center (IMSC). There, an interdisciplinary team of
researchers from engineering and the USC Annenberg School for
Communication are collaborating with researchers at the Keck School of
Medicine of USC to develop a variety of new haptics devices to let
stroke patients get downright pushy with their rehab.
In fact, the patients, who are all in neurorehabilitation at USC
University Hospital, will soon be able to push, grasp, pinch, squeeze
and throw objects in some very novel new virtual reality tasks.
“Haptics, which adds the sense of touch to 3D computing, lets
stroke patients interact with virtual worlds by feel,” says Margaret
McLaughlin, professor of communication at the USC Annenberg School for
Communication and a co-editor of Touch in Virtual Environments.
Commercial gaming was one of the first industries to debut
inexpensive, non-immersive versions of the technology, using
force-feedback joysticks and steering wheels that vibrated as the
driver sped along a video racetrack. But in university
laboratories, the availability of more sensitive, high-end devices that
could render touch sensations in three dimensions quickly led to
applications in more serious pursuits.
“The applications for the blind and visually impaired were readily
apparent, and soon we saw haptics technology in medical and surgical
training programs, flight school, teleoperations and scientific
visualization,” McLaughlin says.
McLaughlin’s colleague, Albert “Skip” Rizzo, a research scientist
at USC’s Institute for Creative Technologies, equates the touchy-feely
virtual environments that are possible now to sophisticated aircraft
simulators.
“It’s very much like creating an aircraft simulator to test and
train pilots,” he says. “But now we’ve created simulations that
can assess and rehabilitate a stroke patient under a range of stimulus
conditions. These are conditions that aren’t easily deliverable
or controllable in the real world.”
NIH Grant
In 2004, IMSC researchers and their counterparts in the psychology
department at the University of Texas, Austin, were awarded a $1.8
million grant from the National Institutes of Health to begin
collaborative work on a variety of new haptics interfaces with
researchers at the Keck School of Medicine of USC.
|
This
therapeutic environment utilizes a “cyber grasp” exoskeleton, which
fits over an instrumented data glove that measures the position and
orientation of the hand in a 3-D space. |
NIH awarded the grant “to explore new directions in
neurorehabilitation,“ according to principal investigator Thomas
McNeill, professor of cell and neurobiology, neurology and
neurogerontology at the Keck School.
“The need was there,” he said. “More than 700,000 people
suffer a stroke each year and nearly 450,000 survive with some form of
neurologic impairment or disability.”
Those numbers will grow, as the population ages and obesity and
heart disease increase, making innovative rehabilitation programs “a
national priority” in the next 50 years, McNeill predicts.
So a group of talented faculty and Ph.D. students working in
IMSC’s Haptics and Virtual Environments Lab — including McLaughlin ,
Rizzo, Younbo Jung, Wei Peng, Shih-Ching Yeh and Weirong Zhu — dove
into new applications.
They came up with an interesting assortment, including the
“pincher.” This device is designed for two-fingertip contact with
virtual objects, say Zhu and Yeh, who write computer programs for the
systems.
The game (or cyber task) works like this: The user dons a pair
of stereoscopic goggles and puts a thimble on the forefinger; the
thimble is connected to a robotic force-feed device, called a
PHANToM. The stylus of a second PHANToM is affixed to the thumb.
The two PHANToMs provide the sensation of force to the user’s
fingertips as she/he tries to pick up a 3D cube and
squeeze it small enough to fit through a narrow hole on the computer
screen.
|
A
stroke survivor in rehabilitation holds a ball in his impaired hand and
rotates his wrist to move objects around on the screen. His wrist
movements are tracked and precisely measured. |
Mutual Touch
Another interface is the “mutual touch” task for hand-reaching and
grasping exercises. This therapeutic environment utilizes a “cyber
grasp” exoskeleton, which fits over an instrumented data glove that
measures the position and orientation of the hand in a
three-dimensional space.
“The glove allows patients to feel the sensation of a solid object
in their palms,” says Yeh, who concentrates more on the computer
graphics. “Among the tasks they might be able to perform are
picking up a glass and inverting it to pour the liquid out or picking
up books and stacking them on appropriate shelves.”
The interfaces give physical therapists precise control over a
stroke patient’s exercise program, which is key to recovery, McLaughlin
adds.
“We can tailor rehabilitative tasks, like pouring milk out of a
glass, to each patient, depending on what level of impairment they have
sustained,” she says. “We also get information on their
performance instantly, which helps the therapist to design a
rehabilitative program of increasing difficulty. “
In clinical pilot tests at the USC Keck School — led by Carolee
Winstein, professor of biokinesiology and physical therapy and
co-principal investigator on the NIH grant, and Ph.D. student Jill
Stewart — stroke patients have reported their “overall satisfaction”
with the new computer tasks. In one instance, a volunteer was
“extremely enthusiastic” about the space tube task and said she wanted
to use the system at home.
That is critical to post-stroke recovery. “It’s not easy to
keep patients motivated and engaged in daily, repetitive exercises,”
McLaughlin says, “so if they are enjoying the tasks, they’re likely to
do better during rehabilitation.”
|
The
space tube challenges users to move the ball into the entrance of the
tube, indicated by the arrow, and push it through without banging into
the walls. |
Telerehabilitation
“Telerehabilitation” is another interface currently in
development. This interface will be web-based, allowing both the
therapist and the patient to log in to a private site, where goals for
the patient’s recovery phase can be set.
Patients will be able to select goals based on their individual
lifestyles and send them to the therapist for review, the researchers
say. The therapist will be able to discuss those goals with the
patient via a peer-to-peer audio conferencing feature embedded in the
web page.
“The interface will allow patients to take the initiative in setting
their own goals for recovery, and then allow for further discussion and
negotiation of those goals later,” McLaughlin says. “It’s a way
of keeping the patient connected to the therapist and of encouraging
patients to set their own goals and become more responsible for their
own recovery.”
--Diane Ainsworth
