Advanced Positioning System for Harsh Environments Using Time-Varying Magnetic Field

Harsh environments, which are complex, mutable, and hard to model, prevent high-accuracy positioning and navigation. In this article, a novel magnetic-based positioning system (MBPS) based on a low-frequency time-varying magnetic field (MF) is reported. Related investigations have shown that low-frequency MF signals have better propagation characteristics in harsh environments and achieve good penetration into obstacles. Unlike the intensity decay method, our proposed method is not affected by the uncertainty of the intensity decay model caused by the complex magnetic medium. The novelty of our proposed approach lies in the large effective coverage, outstanding penetrability, and rapid results offered by it compared with those of the traditional method, achieved using a constant magnetic feature vector as the observation. Furthermore, considering the installation error of the magnetic beacon (MB), which is hard to avoid and measure, we proposed an improved Rao-Blackwellized particle filter (RBPF) algorithm to estimate the receiver position and installing error on the position and angle. For the proposed MBPS, the best accuracy of 0.06 m can be reached under conditions at which the installing position error is 0.5 m and the angle error is 10°-15° with daily electromagnetic interference. The MB and its model verification were also investigated. In summary, the effectiveness of the proposed MBPS and the algorithm was verified sufficiently in this study.