Feedback about hand position and gripping force through stimulation of the skin to be used in forearm prostheses.

Feedback, directed to the user, about hand position and grasping force is missing in current myoelectric forearm prostheses, which impedes the subconscious control of the prostheses. In this study, the use of electrotactile and vibrotactile stimulation to provide this feedback will be evaluated. The study is splitted in four parts. In part 1 position (hand opening) feedback is studied, in part 2 (grasping) force feedback and in part the combination of position and force feedback. These three parts will be performed on 15 healthy subjects per study. In part four of the study, the optimal stimulation settings will be evaluated on amputation patients. For all studies, the task to be performed is a grasping task in which a virtual hand is controlled by the scroll function of a mouse and feedback is provided by electrotactile or vibrotactile stimulation on the same (fore-)arm. Feedback conditions (modality, placement of stimulator, presence of visual feedback) will be varied over the different tasks.

Feedback about hand position and gripping force will improve the control of forearm prostheses by reducing the time needed to perform grasping tasks and the errors made during these tasks.

1 day (everything is measured on the same day).

All subjects will be asked to perform, as accurate and fast as possible, several grasping tasks. A (virtual) hand will be shown on a computerscreen and the level of hand opening and/or the grasping force can be controlled by the computermouse. During the task, the level of hand opening and/or the grasping force will be fed back to the subjects arm through vibrotactile or electrotactile stimulation. Stimulation parameters (number of stimulators, placement of the stimulators), feedback method (electrotactile or vibrotactile) and the presence or not of visual feedback will be varied over the different tasks. Every subject will experience the same set of tasks (although in random order presented) and the duration of the whole experiment will be 2 hours.