LotusBraille: Localised Multifinger Feedback on a Surface for Reading Braille Letters

Digital tactile surfaces are an integral part of our everyday life, through our smartphones, ATMs or home appliances. Even though they rely on touch interaction, they are devoid of rich and multipoint tactile feedback, thus leaving the visual and the auditory modalities as the main ones to convey content. Therefore, these surfaces pose accessibility challenges to the visually impaired, imposing reliance on text-to-speech engines or external peripherals such as Braille displays. This can be impractical in noisy or crowded environments, or for short-term usage. One important issue is Braille rendering; current technologies are not able to render Braille dots at the mm scale with vibrotactile technologies, mainly as vibrations propagate to the entire surface. Alternative technologies or rendering methods have been investigated but most rely on dedicated displays or have used workarounds to provide localised Braille on a surface, either with a different encoding, wearables or add-ons. With our latest achievements in localised multipoint haptic feedback on a surface, with the Inverse Filter method, we evaluated this technology, called LotusBraille, to convey Braille letters based on the Perkins Brailler input method with visually impaired users and obtained promising results.