Error Reduction in Magnetoquasistatic Positioning Using Orthogonal Emitter Measurements

Measurements of the emitted magnetoquasistatic fields generated by a vertical emitting loop and detected at the terminals of seven fixed vertical receiving loops, all located above earth, are used to solve for position and orientation of the emitter. The coupling between the mobile emitting and fixed receiving loops was measured over a 3 × 3 emitter grid spanning an 18 ×18-m
²
area and for azimuthal orientations between 0
^°
and 330
^°
at 30
^°
increments. Inverting the theoretical coupling expressions for two-dimensional position and azimuthal orientation resulted in a mean position and orientation error of 0.62 m and 2.86
^°
, respectively. Calculations including orthogonal-emitter configurations resulted in a mean position and orientation error of 0.21 m and 1.12
^°
, respectively, which represents a 66.1% and 60.8% reduction in error, respectively.