An innovative tool for designing fault tolerant cockpit display symbology

This research focuses on the design and development of a software package to aid display designers in creating fault tolerant fonts and symbology for monochrome dot-matrix displays. Since dot-matrix displays are subject to non-catastrophic failures [rows, columns, and individual picture elements], display designers find it necessary to address hardware reliability as a key design element when avoidance of operator reading errors is mission critical. This paper addresses row and column failure modes. Building redundancy into the design of font characters and symbology can provide additional protection from reading errors. The software package developed for the design of fault tolerant fonts, referred to herein as FontTool, operates on an IBM PC or compatible hardware platform within a Microsoft DOS environment. FontTool can simulate row or column dot-matrix display failures and “predict” likely human reading errors. Based on limited testing, FontTool reading error “predictions” were found to be consistent with actual human performance reading error data about 86% of the time. FontTool uses Euclidean distance between 2-D Fourier transformed representations of dot-matrix characters as a metric for predicting character “similarity”. Although this metric has been applied previously, FontTool is a major advance in aiding display designers to build more fault tolerant cockpit display symbology