Analysis of Nonideal Effects and Performance in Magnetic Positioning Systems

The influence of the environmental configuration on ac magnetic distance and position measurement systems, which are based on inductive coupling of tuned resonators, is experimentally analyzed. The main aspects that affect the accuracy of such systems are the conductivity of the terrain and the presence of metallic materials near the resonators. It is shown that such aspects are frequency dependent, and a tradeoff is to be considered between the maximum operating range and the error. Moreover, a strategy to detect if the measurement results are corrupted by the environmental configuration is presented. The analysis is then extended to a positioning scenario where the prototype of a magnetic positioning system (MPS) is deployed and a comparison with a commercial ultrawideband (UWB) system is performed. The results show that the MPS performance is comparable with the commercial UWB system, leading to a mean positioning error of the order of 0.6 m when using an extended Kalman filter-based positioning algorithm.