Contribution to the Design and Implementation of Portable Tactile Displays for the Visually Impaired

Abstract

This thesis explores the design, implementation and performance of a new concept for a low-cost, high-resolution, lightweight, compact and highly-portable tactile display. This tactile device is intended to be used in a novel visuo-tactile sensory substitution/supplemen-tation electronic travel aid (ETA) for the blind/visually impaired.Based on the psychophysiology of touch and using Shape Memory Alloys (SMAs) as the actuation technology, a mechatronic device was designed and prototyped to stimulate the sense of touch by creating sensations of contact on the fingertips.The prototype consists of an array of 64 elements spaced 2.6 mm apart that vertically actuates SMA based miniature actuators of 1.5 mm diameter to a height range of 1.4 mm with a pull force of 300 mN up to a 1.5 Hz bandwidth. The full display weights 200 g and its compact dimensions (a cube of 8 cm side-length) make it easy for the user to carry. The display is capable of presenting a wide range of tactile binary information on its 8 x 8 matrix. Moreover, both mechanical and electronic drive designs are easily scalable to larger devices while still being price attractive.Human psychophysics experiments demonstrate the effectiveness of the tactile information transmitted by the display to sighted people and show feasibility in principle of the system as an assistive technology for the blind/visually impaired.