Finite Element Analysis of Human Tactile Sensing to Differentiate Thin Foils through Comparison Between Vertical & Angled Loads

Due to increasing research demand on human tactile sensations for robot-human interfaces and new tactile sensors, this research studies human tactile sensing to differentiate the thicknesses of two extremely thin foils that are made of Cu and stainless steel (SUS). We performed finite element analysis (FEA) on the fingertip's 3D elastic model to improve previous simulations through error analyses, better selection of nodal points, and proper loading conditions. We obtained the optimum mesh size to achieve numerical error below 4%. We also compared the von Mises (VM) stress of Cu with one of the SUS foils under different loading states to monitor the tc/ts ratio calculated from the thicknesses of the Cu and SUS foils that cause identical VM stress. The simulated result shows that the ratio becomes considerably large when thicknesses tc (Cu) and ts (SUS) are calculated from the differences of the VM stress between the angular and vertical loads. Consequently, the difference between the twitch motion and the datum provides the best ratio, tc/ts = 1.6, which resembles the results of psychophysical experiments.