Psychophysical Evaluation of A Mechanotactile Haptic Feedback Device

Sensory feedback enhances the intuitive operation of upper limb prostheses. However, most modern commercial prosthetic devices lack sensory feedback mechanisms due to the difficulty of integration and added complexity. Mechanotactile haptic feedback provides a non-invasive and low-cost alternative to traditional electromechanical haptic feedback modalities. While mechanotactile haptic feedback systems have been studied for their mechanical behaviour, their practical integration in prosthetic devices and associated human factors still remain to be investigated. Therefore, in this paper, we perform a psychophysics study to investigate the perceptual thresholds associated with a mechanotactile feedback system. We use a mechanotactile sensory system and feedback device to provide force feedback on the forearm of healthy volunteers. We systematically assess the optimal placement of the feedback devices and the minimum perceptible forces at each position. We found that the minimum perceptible force that a user can perceive range lies in the range of 0.39 N to 1.36 N at various points on the forearm. The distal forearm was found to have higher perception sensitivity compared to the proximal forearm. Our results shed light on the perception thresholds achievable with mechanotactile haptic elements. Results also indicate that proper placement and site selection of the mechanotactile feedback elements are crucial to enhance force perception accuracy.