Remote tracking of a magnetic receiver using low frequency beacons

Abstract

Low frequency magnetic fields feature high penetration ability, which allows communication, localization, and tracking in environments where radio or acoustic waves are blocked or distorted by multipath interferences. In the present work, we propose a method for tracking a magnetic receiver using beacons of low frequency magnetic field, where the receiver includes a tri-axial search-coil magnetometer. Measuring the beacons’ magnetic fields and calculating the total-field signals enables localization without restrictions on magnetometer orientation, allowing on-the-move tracking. The total-field signals are used by a global search method, e.g., simulated annealing (SA) algorithm, to localize the receiver. The magnetic field produced by each beacon has a dipole structure and is governed by the beacon’s position and magnetic moment. We have investigated two different methods for estimating beacons’ magnetic moments prior to localization. The first method requires directional measurements, whereas for the second method the total-field signal is used. Effectiveness of these methods has been proved in numerous field tests. In the present work, we introduce a method for tracking a moving receiver by successive localizations. Using previous localization as a starting point of the search method for the next localization can reduce execution time and chances for divergence. The proposed method has been tested using numerous computer simulations. Successful system operation has been verified in field conditions. The good tracking capability together with simple implementation makes the proposed method attractive for real-time, low power field applications, such as mobile robots navigation.

Underground Incrementally Deployed Magneto-Inductive 3-D Positioning Network

“…Reliable through-the-earth communication has been addressed in [17] and [24], but it did not consider localization. In [44], a numerical MI tracking solution using monoaxial TX coil and triaxial search-coil magnetometer as RX was proposed, but its operation environment is unknown. MI techniques for geophysical prospecting have been addressed in [10].…”

A mechanically based magneto-inductive transmitter with electrically modulated reluctance

“…Lockheed Martin in response to such disasters developed an MI system for wireless communications with underground mine workers known as MagneLink [ 8 ]. In addition to low-frequency wireless, work has also gone into developing MI based underground, underwater, and indoor navigation for a variety of applications [ 2 ], [ 9 ]–[ 10 ].…”

Modelling and optimizing through-the-Earth radio transmissions

“…In contrast to the previous theme of assessing the feasiblity of a communication link, more varied studies were done. One avenue of research was direction finding, where it was investigated whether below ground signals could be used to estimate the position of a trapped miner (Geyer and Keller, 1976;Hill and Wait, 1982;Lagace et al, 1980;Large et al, 1973;Olsen and Farstad, 1973;Pittman et al, 1985), although this problem largely remains open today (Sogade et al, 2004;Ayuso et al, 2010;Sheinker et al, 2014) given the complexity involved in accounting for the distortion of an electromagnetic signal by a conductive ground. Another line of work was using TTE transmissions to constrain the conductivity structure of a mine overburden (Geyer et al, 1974;Lagace et al, 1980;Durkin, 1984aDurkin, , 1991, by measuring the received signal underground.…”

“…In the 1970s and 1980s, TTE radio research sponsored by the Bureau of Mines (United States Department of the Interior) was particularly focused on the problem of detecting a miner's signal (Olsen and Farstad, 1973;Geyer et al, 1974;Lagace et al, 1980;Durkin, 1984b), which remains a challenging problem to this day (Sogade et al, 2004;Ayuso et al, 2010;Sheinker et al, 2014). In the ideal case where the Earth is homogeneous, a miner's position can be estimated by locating the null of the radial magnetic field transmitted by a vertical magnetic dipole underground; in addition, at the same position, the vertical magnetic field will reach a peak.…”

“…In the ideal case where the Earth is homogeneous, a miner's position can be estimated by locating the null of the radial magnetic field transmitted by a vertical magnetic dipole underground; in addition, at the same position, the vertical magnetic field will reach a peak. A drawback of this approach is that sophisticated modelling is needed to account for complicated conductivity structures that distort the magnetic field (Ayuso et al, 2010;Sheinker et al, 2014). From this observation, Sogade et al (2004) developed a method to map caves by locating the depth and position of a signal transmitted underground;…”