Determination of the parameters of a dipole by measurement of its magnetic field

A novel method to determine the parameters (dipole moment, orientation, and location) of a magnetic dipole is discussed. The method, which requires no a priori knowledge of the parameters, consists of measuring one or more components of the magnetic field of the dipole in a two-dimensional grid and performing a two-dimensional multiparameter nonlinear least squares fit to the data. Results of computer simulations which include the effects of electronic and sensor noise and motion of sensors are presented to show that reliable and consistent parameter estimation is obtained and that pseudoreal-time operation is achievable on a fast minicomputer. The simulations are valid for all major classes of magnetometer sensors. Further, application of the method to experimentally obtained data is discussed. Simulation and experiments show that for objects situated 60-200 cm from the plane of sweep of the sensors, which yield peak field values
\sim 10-1000
nT, magnetic data must be accurate to within a few nT which is easily achieved using fluxgate sensors, and position accuracy of
\pm 1
cm over a span of 700 cm is sufficient.