Differences between Individuals with Temporal Change in Plantar Surface Contact Area in Walking Motion

Here, we present a method for extracting individual human qualities based on the detection of the plantar surface contact area in a walking motion, with the use of a high-speed camera system with 150 frames per second. This technique captures images of the plantar surface contact area through a transparent acrylic slab by using the evanescent waves that form on the transparent acrylic surface where the plantar touches. Images were obtained of the temporal changes in the plantar surface contact areas of 14 healthy individuals between 22 and 23 years of age using the proposed technique. Subtle characteristics were derived from the temporal changes in the plantar surface contact areas obtained from their waveforms. There were differences because the waveforms reflected, not only differences between the shapes of individual soles but also the plantar skin deformations of each individual. This suggests that the extraction of individual qualities based on subtle differences in the temporal changes in the plantar surface contact area can be achieved using the proposed technique.