A global self-localization technique utilizing local anomalies of the ambient magnetic field

Magnetic field fluctuations in modern buildings arise from both natural and man-made sources, such as steel and reinforced concrete structures, electric power systems, electric and electronic appliances, and industrial devices. If the anomalies of the magnetic field inside the building are nearly static and they have sufficient local variability, they provide a unique magnetic fingerprint that can be utilized in global self-localization. In this article, a Monte Carlo localization (MCL) technique based on this hypothesis is proposed. The feasibility of the technique is demonstrated by presenting a series of global localization experiments conducted in four arbitrarily selected buildings, including a hospital. The experiment setup consists of a mobile robot instrumented with a 3-axis magnetometer and a computer. In addition, successful human self-localization experiments were conducted by using a wireless wearable magnetometer. The reported experiments suggest that the ambient magnetic field may remain sufficiently stable for longer periods of time, giving support for self-localization techniques utilizing the local deviations of the field.