A Shape Display Method Based on Electromagnetic Localization and Actuation

Abstract

A 3D shape display method based on electromagnetic localization and actuation is presented and the correspondent miniature device is developed. Evaluation of the single actuator device shows that majority of shape information can be delivered. The device containing multiple actuators is designed to improve the small shape and large curvature perception. The scaling analysis of EM force is performed to determine the maximal allowable actuators per unit area. The prototype device containing 4 £ 4 actuators array is developed for further evaluation. The need to display graphics to visually impaired people has been growing with the emergence of World Wide Web (WWW). Although several types of computer-aided software were devised to transfer selective information into Braille language, the major obstacle of the communication for the visually impaired people is the deflcient delivery of the graphic information. As a reason, the interest has arisen in developing shape display devices. Electronic devices aiming to fulflll this function can be categorized into two groups. One is to use active touch method where the proflle of the shape is produced by using a tactile matrix (1,2) or virtual environment through force feedback (3). These devices, however, either demand a relatively large platform to incorporate a touching interface, or require large driving element to produce enough force to users. The other group of devices is to use passive sensing method where the pattern is locally produced onto human skin by using spatially discriminated stimulation (4), which is mainly successful for two dimensional graphs. This paper presents an approach that combines both active and passive tactile method to dis- play three dimensional virtual objects by using the miniature vibrator(s). The presented device incorporates an electromagnetic (EM) position detector and EM actuator(s) to selectively stimu- late user's flnger based on its location. The working principle is shown by the block diagram in Figure 1. Human brain interacts with the EM actuator as receiving stimulation and guides the flnger to move following user's estimate of the reference shape. The position comparison results in a decision to engage the actuator in selective locations. The iterations of receiving stimulation and modifying shape estimates produce to users an optimal estimation of the shape.