A New Sensory Feedback System for Lower-Limb Amputees: Assessment of Discrete Vibrotactile Stimuli Perception During Walking

Sensory feedback systems can improve gait performance of lower-limb amputees by providing information about the foot-ground interaction force. This study presents a new platform designed to deliver bilateral vibrations on the waist of the user, synchronously with specific gait events. Preliminary perceptual tests were carried out on five healthy subjects to investigate the perception thresholds on the abdominal region. The reaction time and the percentage of correct perceptions were computed to compare three stimulation levels: 50%, 70% and 100% of the maximum vibration amplitude (i.e., 1.5 g, 1.9 g and 2.2 g). The reaction times decreased with higher activation levels. The percentage of correct perceptions was 40% with 50% stimulation level and higher than 97% with 70% and 100% stimulation levels, respectively. The results suggest that vibration amplitudes of 1.9 g provide vibrotactile stimulation that can be effectively perceived during walking, thus used to convey sensory information.