To effectively replace the human hand, a prosthesis should seamlessly respond to user intentions but also convey sensory information back to the user. Restoration of sensory feedback is rated highly by the prosthesis users, and feedback is critical for grasping in able-bodied subjects. Nonetheless, the benefits of feedback in prosthetics are still debated. The lack of consensus is likely due to the complex nature of sensory feedback during prosthesis control, so that its effectiveness depends on multiple factors (e.g., task complexity, user learning).
We evaluate the impact of these factors with a longitudinal assessments, using a clinical setup (socket, embedded control) and a range of tasks (box and blocks, block turn, clothespin and cups relocation).
To provide feedback, we propose a novel vibrotactile stimulation scheme capable of transmitting multiple variables from a multifunction prosthesis. The interface consist of four uniformly placed vibro-tactors providing information on contact, prosthesis position (e.g., rotation), and grasping force. In addition, we design questionnaires for the subjective evaluation of the feedback.