Fast Nonrecursive Method for Estimating Location and Dipole Moment Components of a Static Magnetic Dipole

Abstract

This paper presents a method of estimating the position and moment components of a static magnetic dipole based on measurements of the magnetic field component normal to an arbitrary plane in which measurements are obtained. The largest local maximum and smallest local minimum of the field component and the corresponding positions in the plane are all the data necessary to obtain the solution. The solution is accurate, nonrecursive, robust, fast enough to be carried out by a 16-bit microprocessor in a fraction of a second, and makes no assumptions about the orientation of the dipole. The method in most cases gives good results for total field data, too. Results of a computer simulation study, which was performed to evaluate the method using simulated but realistic data, are presented. It is found for both total and vector magnetic field data that accuracy of component estimates are nearly independent of magnetic sensitivity (for S/N ratios greater than 28 dB) and sensor positional errors in the plane of measurement (if less than 5 percent of the dipole depth). Percentage error in estimates of dipole position and moment components is approximately equal to the percentage error in sensor position orthogonal to the plane of measurement (if less than 5 percent of the depth).