Development of a broadband tactile display and role of vibration in the tactual perception

Abstract

This paper investigates the development of a broadband tactile display and role of vibration in the tactual perception. Before designing the tactile display, spatiotemporal tactile perceptive characteristics and biomechanical properties of human skin and their implications for the design of tactile displays were investigated. Three separate experiments were conducted. First, vibrotactile thresholds as a function of frequency of vibration were measured using a cylindrical contactor of 0.7mm diameter. The results of the experiment showed similar trends to that of previous physiological results that used a larger contactor. In the second experiment, vibrotactile spatial acuities were investigated. Two-point localization errors were measured on the tip of the index finger and on thenar eminence as a function of frequency of vibration. The results showed that human skin was sensitive to spatial differences at the frequency bands of 1-3Hz and 18-32Hz. The subjects`` spatial acuities gradually decreased as the frequency of vibration increased over 50Hz. In the third experiment, impedances of human skin were measured as a function of frequency of vibration. The results showed that the impedance of the finger pad increased as vibrational frequency increased. However, the impedance of the palm remained steady. From these results, the implications in the designing of spatially distributed tactile displays and methods for texture display haven discussed and they were applied to develop a compact broadband tactile display. A planar distributed tactile display was developed and tests of its effectiveness for displaying textures were studied. The tactile display is composed of a 5×6 pin array actuated by 30 piezoelectric bimorphs. The pins lie on 1.8 mm centers. Vertical excursion of each pin is controlled over a 0-0.7mm range. Perceptual experiments were conducted to evaluate the performance of the system under three conditions: active touch, passive touch with vibration, an...