MagnID: Tracking Multiple Magnetic Tokens

Tangible systems present compelling interaction opportunities but are typically enabled by complex, bulky, awkward or expensive sensing infrastructures. This hinders their adoption in many application areas. In order to address this issue, this paper explores the use of simple active magnetic tokens that create carefully controlled patterns of varying magnetic flux as the building blocks of tangible systems. We describe the construction of these tokens and a software system capable of detecting their presence and inferring their location based on data sampled from a single triaxial magnetometer a standard component of most current mobile devices. The system can recognize token positions from a set of six pre-calibrated locations with an accuracy of 99%. We describe the hardware and software components of this system and five demonstration applications that illustrate its functionality.