Use of a novel sensor to investigate the complicated boundary between biotribology and surface topology and their impact on tactile graphic perception

Abstract

For persons with blindness or significant visual impairment, access to tactually encoded information is vital for full engagement in society. The use of Braille as a tactile communication system for textual information is ubiquitous and standardized. For graphically intensive information such as charts, diagrams and maps, tactile graphics are often employed which encode visual cues via the use of topological features. In contrast to Braille, there is far less standardization of tactile graphics practices because less work has been done to fully understand the complex interplay of biotribology, surface topology and printing technology, which all impact graphic legibility. Previous work by the authors has shown that friction plays a substantial role in tactile perception in some cases, while – counterintuitively – it does not appear to be the dominant perceptual differentiating mechanism with common texture types used in tactile graphics. In this work, the authors evaluated an evidenced-based hypothesis to explain the perceptive ability of evaluators to properly differentiate among select texture patterns that could not be explained by purely friction or wear-based mechanisms. A specialized analytical contact model was employed to predict the number of texture elements in contact with a sliding fingertip as a means to explain previous findings that the inter-element spacing was crucial to perception. A novel sensor was developed which employed electro-active textural elements printed on paper media to confirm the analytical results. Topologically flat texture analogues were also developed to explore the impact of topology on the number of elements in contact during tactile graphic exploration. This approach enabled the authors to determine the texture parameters where tribological effects began to transition to topological impacts. These findings have application to not only optimal tactile graphic design but also to improving the wear and durability of printed graphics on paper media.