Signal Architecture for a Distributed Magnetic Local Positioning System

This paper presents a sensing system which can be used by a mobile robot to measure absolute position and attitude, even in the cluttered environment of an office building or warehouse. The system is based on extremely-low frequency magnetic fields, which have excellent characteristics for penetrating line-of-sight obstructions. Multiple beacons distributed throughout a building are used to generate the magnetic signals, which are based on sets of pseudorandom codes. This signal architecture results in low overall frequency content, reducing eddy field noise and enabling the system to have a large number of beacons and extended coverage volume.