Virtual lattice texture presentation using a tactile mouse featuring a fine pin array (2nd report, examination on pin pitch, texture density and ridge height)

Abstract

In the previous study, we developed a tactile mouse featuring a line pin array, the purpose of which is to be effective in virtual reality and tele-existence systems. It features an 8-by-8 array of stimulus pins each measuring 0.3mm in diameter and with a 1.0- or 1.8-mm pin pitch. Since the stimulus pins within the display's pads can be made to protrude above the pad's surface and their motions are controlled by piezoelectric actuators, the operator can feel various combinations of pins protruding according to the surface texture of the virtual object. In order to establish a design method for the tactile displays, we performed a series of psychophysical experiments using the display. By evaluating variation in threshold for discriminating crossed angles of virtual lattice textures under different pin arrays, texture density, and pin strokes, we determined suitable pin pitch, presentable density and ridge height of the virtual texture. It was found that the two-point threshold should be adopted as the pin pitch between pins in the design of the tactile display. The presentable density and ridge height of the virtual textures were N=50 and δ=0.3mm. Finally, we compared the discrimination precision of virtual textures with those of real textures to evaluate the present tactile display's presentation quality. Since the difference threshold for the real texture was 1/3 that of the virtual texture, the present tactile display should be improved with respect to shearing force presentation to simulate relative motion feeling between the finger surface and virtual object surfaces.