Grasping force and slip feedback through vibrotactile stimulation to be used in myoelectric forearm prostheses

Abstract

User feedback about grasping force or slip of objects is lacking in current myoelectric forearm prostheses, resulting in a high number of prosthesis abandonment, because a high level of concentration is required to hold an object. Several approaches to provide force feedback to the user via vibrotactile stimulation have been described in literature, but none of them have investigated the optimal stimulation parameters. This study describes an evaluation of three modulation techniques to provide force feedback. Furthermore, the same modulation techniques to provide slip feedback were evaluated, which has not been described before. The performance in virtual object holding tasks was significantly improved in most cases compared to the non-feedback situation, but at the cost of an increased task duration.

Feasibility of enhanced user control and feedback in upper leg prostheses

“…Witteveen et al [57] showed that subjects receiving feedback on hand opening and touch without visual feedback, performed better than without any form of feedback. Force and slip feedback were also successfully fed back to healthy subjects and amputees using vibrotactile stimulation [58]. However, timings of the performed tasks were not considered important and correct detection rates were between 30 and 80% [57,58].…”

“…Force and slip feedback were also successfully fed back to healthy subjects and amputees using vibrotactile stimulation [58]. However, timings of the performed tasks were not considered important and correct detection rates were between 30 and 80% [57,58]. Because timing of feedback in lower extremity prostheses is critical and errors might have serious consequences (e.g.…”

“…For the upper extremity experiments, subjects were in control of the stimulation. They were presented a hand-opening position and had to tune the stimulus to reach the desired hand-opening [57,58]. Currently there is no voluntary controlled upper leg prosthesis, therefore performing the experiment similar to these upper extremity experiments would not have been useful.…”

“…Subjects performed better with vibrotactile feedback than with electrotactile feedback. Another study by Witteveen et al [58] showed that force and slip feedback could be provided using vibrotactile stimulation in an array or at one location using frequency modulation. Force levels were correctly estimated in up to 80% of the trials, depending on the task.…”

“…Vibrotactile stimulation in an array at the upper extremity has shown to be effective for providing feedback, however correct detection rates are low and timing was not considered to be critical [57,58]. The (continuous) feedback method presented by Vos et al [147] may be further optimized to increase the detection rate.…”