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The ultimate goal of this
research is to manipulate visual feedback in order to make
robotic therapy more effective than traditional
human-assisted and robotic rehabilitation. Toward this end,
this thesis examines the limits and effects of visual
feedback distortion, a type of visual feedback manipulation,
in a robotic environment. Visual feedback establishes a
metric of performance for a given task, and visual feedback
distortion is defined as a change in this metric such that a
change in performance is required to cause the same visual
response. In order to design a therapeutic program utilizing
visual feedback distortion, it is crucial to identify the
amount of distortion that is imperceptible. Thus, the first
experiment measured the amount of distortion that is
imperceptible (the Just Noticeable Difference, or JND) for
age-matched, unimpaired subjects and motor- impaired
subjects. The second experiment showed that vision dominates
kinesthetic feedback in a robotic environment and that
gradual visual distortion beyond 1 JND increases force
production and movement distance within a single
experimental session. Finally, the third experiment examined
the effects of distortion of movement error during a
two-finger coordination task. The results of this experiment
showed that error distortion is effective in directing a
subject's attention to a specific finger but does not
improve terminal performance. These foundational
experimental results were used to design a game-like
therapeutic paradigm incorporating visual feedback
manipulation. In initial tests with three chronic stroke and
traumatic brain injury patients, all patients followed the
visual feedback manipulation to levels of performance above
that predicted by their initial assessment at each session.
Furthermore, all patients showed functional improvements
after participation in the study. Visual feedback
manipulation has shown promise for therapy in a robotic
environment; more work is needed to further explore the
ramifications of visual feedback manipulation for robotic
rehabilitation and to spread this technique to clinical
practice.
B.R. Brewer, Visual Feedback Manipulation for Hand Rehabilitation in a
Robotic Environment, doctoral dissertation, tech. report
CMU-RI-TR-06-24, Robotics Institute, Carnegie Mellon
University, May, 2006.
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