Locating and identifying compact ferrous objects

A solution to the problem of magnetostatic location and identification of compact ferrous objects of arbitrary shape is presented. It is shown that, in practice, the inversion of the magnetostatic dipole field or field gradient is a necessary first step toward determining object location and identity. Several iterative and noniterative methods of determinating the dipole moment and location from field or gradient measurements are described and compared. It is shown that, given the dipole-moment estimates, it is possible to determine the identity of the dipole source in practical situations by pattern recognition. A unique prototype total field magnetometer which is capable of explicitly and accurately locating and identifying axially symmetric compact ferrous objects is described. It has performed well in preliminary tests using spheres and spheroids