Tap input as an embedded interaction method for mobile devices

In this paper we describe a novel interaction method for interacting with mobile devices without the need to access a keypad or a display. A tap with a hand can be reliably detected e.g. through a pocket by means of an acceleration sensor. By carefully designing the user interface, the tap can be used to activate logically similar functionalities on the device, leading to a simple but useful interaction method. We present results of user tests aimed at studying the usability of various tap input based user interface applications.