SurfaceVibe: vibration-based tap & swipe tracking on ubiquitous surfaces.

Touch surfaces are intuitive interfaces for computing devices. Most of the traditional touch interfaces (vision, IR, capacitive, etc.) have mounting requirements, resulting in specialized touch surfaces limited by their size, cost, and mobility. More recent work has shown that vibration-based touch sensing techniques can localize taps/knocks, which provides a low-cost flexible alternative. These surfaces are envisioned as intuitive inputs for applications such as interactive meeting tables, smart kitchen appliance control, etc. However, due to dispersive and reflective properties of various vibrating mediums, it is difficult to localize taps accurately on ubiquitous surfaces. Furthermore, no work has been done on tracking continuous swipe interactions through vibration sensing. In this paper, we present SurfaceVibe, a vibration-based interaction tracking system for multiple surface types. The system accounts for physics properties of different waves to allow two major interaction types: tap and swipe. For tap induced impulse-like surface waves, we design an algorithm that takes wave dispersion and reflection into account to achieve accurate localization on ubiquitous surfaces. For swipe induced body waves, SurfaceVibe segments signals into 'slip pulses' to localize, and then tracks the trajectory. We validate SurfaceVibe through experiments on different materials and varying surface/sensing area sizes in this paper. Our methods achieve up to 6X decrease in localization error for taps and 3X reduction in length estimation error for swipes compared to existing algorithms that do not take wave properties into account.