Using Sound feedback to counteract visual distractor during robot-assisted movement training

Patient engagement and effort are thought to be important for maximizing the therapeutic benefit of robot-assisted movement exercise after neurologic injury, but little is understood about how the audio-visual feedback presented during training affects engagement and effort. For the study reported here, we hypothesized that visual distraction would decrease engagement during robot-assisted movement training, but that appropriate auditory feedback would counteract this effect. Non-disabled participants (n = 10) participated in a common therapeutic exercise in which they attempted to track a moving target presented on a computer screen as a robotic exoskeleton compliantly assisted their arm movement. Introducing a simple visual distractor significantly increased both tracking error and the interaction forces between the participants and the robot. Introducing auditory feedback of tracking error reduced the effect of the visual distractor, decreasing tracking error and interaction forces toward normative values. If tracking error is taken as a surrogate measure of participant engagement, these results indicate that the presence of even a modest level of visual distraction in the training environment may decrease engagement, and thus present a hazard to the effectiveness of training. However, providing appropriate task feedback through the auditory system can reduce the effect of visual distractors. Therefore, an integrated design of the audio, visual, and haptic environment is important for optimizing robot-assisted movement training.