Dual Validation of a Vibrotactile Armband for Bionic Hands

Abstract

Sensory feedback is essential for natural and reliable bionic-hand control, yet most myoelectric prosthetic hands provide limited or no tactile feedback, and users are forced to rely on visual grip regulation. Vibrotactile feedback is a compact and non-invasive solution, but many existing systems require costly hardware, provide coarse spatial resolution, or lack objective validation of vibration sensing. This study developed and evaluated a low-cost vibrotactile armband that conveys fingertip-specific contact location and force magnitude. Five coin-type vibration motors were spatially distanced on the armband and driven using pulse width modulation at 60% and 90% duty cycles to simulate low- and high- force contact respectively. System performance was evaluated using 1) objective vibration measurements via five accelerometers coupled to each motor, and 2) subjective testing with 20 able-bodied participants under blindfolded, noise-masked conditions. Frequency-domain analysis of the accelerometers' signals showed a dominant peak for the activated motor, and reduced amplitudes at neighbouring motor sites. The participants identified the stimulated finger with 75% and 94% accuracies at low and high force levels, respectively. They could discriminate pinch from grip patterns with 85% accuracy. The combined objective-subjective validation supports the feasibility of this affordable armbandbased feedback for bionic-hand systems.