Proposal of active-wheel-based finger-tactile interface and its slippage-presenting functions

Abstract

The objective of this study is to develop a novel finger-tactile interface employing “active wheel”: the wheel is rotated around its central axis, and the central axis is swiveled around in a vertical axis with any speeds and duration times. The swivel and the rotation, respectively, result in the direction and the speed of slippage on finger-pad skin. The peripheral surface of the wheel provides the slippage, the skin-stretch, the curvature and the edge stimulus to the finger-pad skin, where the push-in quantity of the wheel peripheral surface into skin is considered to be important for the slippage perception and to be dependent on the wheel thickness. Therefore, for improving the slippage perceptual characteristics, we examined an effect owing to a wheel thickness factor, of which levels are a disc or a drum. In addition, we introduced raised-dots on the wheel peripheral surface: the raised-dot creates a sinkage. The dotted wheel rotation provides a dislocation stimulus of the sinkage, which is expected to be effective for slippage perception. Thus, in order to determine the slippage perceptual characteristics, and to select the better wheel configurations with respect to the wheel-thickness and the raised-dots, psychophysical experiments were conducted by introducing four kinds of wheels: “Dot‣Drum”, “Dot‣Disc”, “Smooth‣Drum” and “Smooth‣Disc” wheel. As a result, we found the followings: (1) Dot‣Drum, i.e., the thick wheel with raised dots, is better than the other three wheels for the systematic errors not for the random errors in length perception, (2) Dot‣Drum and Dot‣Disc, i.e., the two dotted wheels are better than the other two smooth wheels for the random errors not for the systematic errors in direction perception.