Virtual Reality
Training for Fall Prevention
David L. Jaffe, MS at the VA Palo Alto Health Care
System's Rehabilitation Research and Development Center and David A. Brown, PT,
PhD at Northwestern University Medical School's Department of Physical Therapy
in Chicago are spearheading a VA funded project involving Virtual Reality (VR)
technology in preventing falls. As one of three interventions being
investigated in the project, VR is being used to study stepping-over responses
in elderly subjects using simulated objects.
The long-term goal of their work is to investigate
techniques to monitor and improve performance in stepping-over obstacles and
train more effective movement strategies of elderly individuals at high risk
for falling.
Brown and Jaffe's VR lab employs a color video camera
trained on the subject's legs from the side. The computer generates images of
rectangular objects of various heights and lengths. The combined image of the
legs and virtual objects is presented in a head-mounted display (HMD).
Subjects wear the HMD as they walk on the treadmill,
stepping over the virtual obstacles they see at their feet. The combined
leg/obstacle video is analyzed by the computer for intersections of the
subject's feet with the virtual obstacles. A collision by the toe on the front
edge of the obstacle would indicate that the subject did not lift the foot high
enough, while a collision with the heel on the top of the obstacle would
indicate the subject did not step far enough. As these collisions are detected,
vibro-tactile feedback is applied to the heel or toe of the foot involved in
the collision.
All subjects walking on the treadmill wear an overhead
harness to prevent injury in the case of a loss of balance or fall.
When stepping over obstacles during over-ground walking, young,
healthy persons step over higher objects by increasing knee and hip flexion,
and when stepping over longer objects they increase stride length. A pilot
study verified this same strategy is employed when stepping over the
computer-generated obstacles displayed during the treadmill walking.
In a small group of elderly subjects, the training
regimen showed a positive result in that subjects were better able to negotiate
an over-ground obstacle course after three training sessions. Jaffe and Brown
plan to perform a randomized, controlled study to separate out the nonspecific
effects, and have plans to further develop the system so that it can be used in
a wide variety of clinical settings and clinical populations.
Future work on this project may explore simulation
techniques with walking aids such as canes and crutches. Other potential areas
of research include the study of improvements in fitness and gait through
simulation of walking situations for ambulatory nursing home patients and
teaching environmental factors and modifications of avoid falls. The system
could potentially provide an enjoyable and safe environment for general
exercise, a safe setting for "wanderers", or a simulated practice
session for way-finding and familiarization of nursing home patients with their
facility.
For more information about the project, contact David L.
Jaffe, MS, VA Palo Alto Health Care System, Rehabilitation Research and
Development Center; or David A. Brown, PhD, PT, Northwestern University Medical
School, Department of Physcial Therapy;
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