Visual Text Entry based on Morse code Generated with Tongue Gestures

〈Summary〉 We propose a vision-based Human-Computer Interface for Text Entry. The system uses a web camera for detecting tongue protrusion gestures, which are interpreted as the signals of International Morse Code. These gestures can be generated independently; hence, the traditional 3:1 ratio between dashes and dots can be disregarded. Employing Morse code for text entry requires memorizing it in advance. In this paper, users are provided with a Visual Chart where input characters are displayed on the screen. Navigating the chart in order to select a character matches perceptually the position of the tongue gestures. Thus, without previous knowledge of Morse code, users are able to start typing just by looking at the screen. Furthermore, the proposed interface allows learning the code by associating it with the tongue actions, while already obtaining tangible results. The Text Entry protocol consists of Timers that can be adjusted according to the level of expertise of users. The best text entry rate obtained was 2.54 WPM. We also provide a method to calculate theoretical speeds, which indicate the lower bound for the speeds obtained in practice. Finally, the Visual Chart contains 30 characters; however, it is possible to expand it in order to encode more information while maintaining the same text entry protocol.