Stochastic relationships between the normal and shear interaction forces during tactile exploration of textures

Abstract

Humans recognize textures through the interaction induced by the normal and shear forces generated between the human fingertip and the surface of objects. We investigated the stochastic relationships of these two axial forces during tactile exploration. The characteristic values of the elliptical distribution obtained by the variations of the two axial forces were analyzed. It was found that the sizes, shapes, and gradients of the elliptical distribution of the low and high frequency forces statistically varied among the 18 types of textures. Especially, the importance of the shape and gradient of the force distribution were revealed by analyzing the stochastic relationships between the two axial forces. The fact that the statistical values of two axial forces depend on the surface of material can be a new aspect to understand human texture perception.