JND Analysis of Texture Roughness Perception using a Magnetic Levitation Haptic Device

This paper describes the use of a magnetic levitation haptic device (MLHD) to study the psychophysics of texture roughness. Studies of texture roughness perception performed using real textures can be time consuming and expensive. By using a MLHD to simulate texture we are able to quickly and easily adjust texture parameters. A dithered textured surface composed of conical elements is simulated using a constraint surface algorithm. The constraint surface shape is defined by the geometry of the elements as well as the size and shape of the virtual probe. The spacing of the elements and the size of the probe can be varied continuously and in real time. Just noticeable difference (JND) experiments were conducted over the parameters of probe radius and texture spacing. The JND of roughness was determined with respect to element spacing using unforced weighted up-down adaptive threshold estimation. JND's were found to vary for texture spacing and probe size. JND's for constant probe size decreased with increasing texture spacing to a minimum and then increased again. JND's for constant spacing increased as probe size increased. These results are consistent with a geometric model of probe-texture interaction