An increased precision position sensor includes a first magnetic field
sensing device; a second magnetic field sensing device; and a processor,
the processor further includes a calibrator; a mathematical model to
predict the magnetic field at a given position relative to the object;
and an estimator algorithm to compare the measured magnetic field within
the predicted magnetic field, thereby calculating the most likely
position of the position sensor relative to the magnetic object. A
position sensor in accordance with the invention is capable of locating
the axis of a cylindrical magnetic object to within .+-.0.5 mm through 70
mm thick aluminium, and is expected to find application, in the aerospace
industry, or other industries where high precision during manufacture is
required. The invention may be conveniently embodied in a portable,
handheld device.