Localization of a Mobile Platform Equipped With a Rotating Magnetic Dipole Source

In this paper, we propose a method for indoor localization based on quasi-static magnetic fields. High penetration ability and absence of multipath effects make it advantageous over other indoor localization techniques based on electromagnetic or acoustic waves. Moreover, the circular rotating magnetic field's specific structure enables it to be distinguished from common magnetic interferences, which generally lack this feature. A dual-axis search-coil magnetometer is placed at a known location with a known orientation and it is used to localize the mobile platform equipped with a source of a rotating magnetic field. We have carried out a theoretical analysis obtaining closed-form expressions for the bearing and distance. The analytical expressions allow calculations without high computational complexity as often required by the numerical analysis methods. The localization method has been tested using a computer simulation in order to evaluate its performance. We have developed a system prototype that has been successfully tested in our laboratory. In a test area of 7 m ×7 m, the experimental results yield a mean localization error of 0.11 m and a maximal localization error of less than 0.29 m. The high accuracy of the method and the absence of resource-intensive calculations allow low-power, real-time implementation.