On cross-axis effect of the anisotropic magnetoresistive sensors

The cross-axis effect error of typical AMR sensor can reach ±1100 nT in the Earth's field, which in the worst case may result in ±2.4° error in azimuth reading of triaxial anisotropic magnetoresistive (AMR) compass. In systems, which cannot use flipping or feedback, the cross-axis error can be numerically corrected, if we know the sensitivity and field scale constant (anisotropy field) of the particular sensor. Three new methods to measure this constant are presented: the field steps using Helmholtz coils, the sensor rotation in geomagnetic field and four-point calibration in geomagnetic field. The measurements performed for Honeywell HMC1002 sensor show that the last method gives lowest uncertainty. The correction iteration algorithm using measured constant reduces cross-axis azimuth error below ±0.04°.