Robust, Low Cost Indoor Positioning Using Magnetic Resonant Coupling

We describe the design, implementation, and evaluation of an indoor positioning system based on resonant magnetic coupling. The system has an accuracy of less than 1 m(2) and, because of the underlying physical principle, is robust with respect to disturbances such as people moving around or changes in room configuration. It consists of 16x16x16 cm transmitter coils, each able to cover an area of up to 50 m(2), and provides location information to an arbitrary number of mobile receivers with an update rate of up to 30Hz. We evaluate the actual accuracy of the positioning with a robotic arm and show quantitatively that even large metallic objects have little effect on the signal. We then present an elaborate study of the performance of our system for the recognition of abstract locations such as "at the table", "in front of a cabinet". It comprises four different sites with a total of 100 individual locations some as little as 50 cm apart.