This paper proposes an alternative activity tracking and
small-scale localization method based on inverse use of
3D digital compass sensors. In our approach, a number
of magnetometer sensors are placed within the
monitored environment in order to detect magnetic
interference introduced by a simple permanent magnet
carried by the study subject (human or animal). Digital
compass sensors are low-cost, low-power with minimal
data processing requirements. Permanent magnets, in
turn, do not require batteries and can be safely worn
for prolonged periods of time (for example, as a
bracelet) [1]. Magnetic tracking is less intrusive than
surveillance cameras and does not require line of sight.
The rest of the paper is organized as follows. The next
section provides a brief overview of related work on
micro-localization and activity tracking methods and
their limitations. Then we introduce the concept of
magnetic tracking and discuss its benefits, limitations
and open challenges. The paper concludes with the
early results of proof-of-the-concept experiments