Dielectric Elastomer Actuators and Optical Character Recognition in a Braille Display

Abstract

The purpose of this study was the development and experimental validation of a novel portable tactile braille reading device. This design aimed to address the lack of quality braille reading material in South African schools dedicated to the blind and visually impaired. The design was divided into four subsystems: the actuation of the refreshable braille display, the mechanical design of the hand mounted device, the Optical Character Recognition (OCR) software and the electronic control system. The objectives of the study included the design of the electrical, mechanical and software subsystems of the device with emphasis on miniaturisation and a low-cost design, as well as the experimental validation of the haptic feedback and OCR subsystems. The system validation focussed on the experimental analysis of the OCR software design and the Dielectric Elastomer Actuators (DEAs) utilised in the refreshable display. The performance of low-cost elastomer and electrode materials were experimentally assessed during the design of the miniature DEAs. The ideal material combination for the proposed application was identified as a VHB4910 acrylic film lined with MG Chemicals 846 carbon grease. The largest vertical deflections of the diaphragm-type DEA were attained with a stipple-based electrode application, with the elastomer prestrained to 300 % initial area. The OCR program analysis indicated that multiple character recognition was more efficient and less prone to inaccuracies than the initially proposed single character recognition method. The integration of OCR software with miniature DEAs served as a novel approach to text-to-braille transcription.