CMU RI Thesis Oral: Visual Feedback Manipulation for Hand Rehabilitation in a Robotic Environment

Bambi Roberts Brewer, Robotics Institute, Carnegie Mellon University
18 April 2006

Abstract: In this thesis, I examine how manipulations of the visual feedback given to a patient can be used to make robotic therapy more effective than traditional human-assisted therapy and previous robotic rehabilitation applications. Patients may not strive for difficult goals in therapy due to entrenched habits or personality variables such as low self-efficacy or a fear of failure. Visual feedback manipulation can be used to encourage patients to move beyond an established level of performance. Specifically, I examine two types of visual feedback manipulation: visual distortion and visual progression. By “visual progression,” I mean veridical visual feedback emphasizing and encouraging gradual improvements in performance; by “visual distortion,” I mean visual feedback that establishes a metric of performance for a given rehabilitation task and then gradually changes this metric such that improved performance is required for the same visual response. For a therapeutic program involving distortion to be most effective, patients must not detect the visual distortions. Thus, the first set of experiments I conducted addressed the limits of imperceptible visual distortion with unimpaired subjects. Further experiments with unimpaired subjects were conducted to show that vision dominates kinesthetic feedback in our robotic rehabilitation environment and that gradual visual distortion can be used to control force production and movement distance within a single experimental session. I also examined the effects of distortion during a difficult two-finger coordination task. Based on this work, I designed paradigms applying visual feedback manipulation to the rehabilitation of chronic stroke and traumatic brain injury patients. I performed initial tests with three patients, each of whom participated in a 6-week rehabilitation protocol. Patients' performances during the initial assessment at each therapeutic session were found to be an underestimate of their actual abilities and a poor metric for setting the difficulty level of therapeutic exercise. All three patients were willing and able to improve their performance by following distortion or progression, and all patients showed functional improvements after participation in the study. Visual feedback manipulation may provide a way to help a patient move beyond his or her self-assessed “best” performance, improving the outcome of robotic rehabilitation.

Further Details
A copy of the thesis oral document can be found at http://www.cs.cmu.edu/~broberts/Dissertation.pdf.