Tilt-based support for multimodal text entry on touchscreen smartphones: Using pitch and roll

Abstract

In this paper we propose a multimodal text entry method for touchscreen smartphones, where standard Tap modality can be used in combination with Pitch and Roll movements that change the orientation of the mobile device. Data from the built-in orientation sensors are used as a basis for commands that support character layout changing. Tilting the device in the appropriate direction will cause visual enlargement of the corresponding half of the current keyboard layout, thus enabling easier character selection, and solely sensor-based text entry. The prototype implementation of the proposed interaction method is analyzed and evaluated via usability testing experiments, with special focus on efficiency of text entry. As the proposed method is also applicable on touchscreen tablets, the form factor of mobile devices is reviewed with respect to text entry performance both of supported interaction modalities (tiltonly and tilt-and-tap) and of possible device orientations (portrait and landscape). © 2013 Springer-Verlag Berlin Heidelberg.