Calibration of Off-the-Shelf Anisotropic Magnetoresistance Magnetometers

Abstract

Magnetometers based on the anisotropic magnetoresistive effect are used in many applications for orientation determination, by measuring the magnetic field of the Earth. As sensors of this type are commercial, off-the-shelf components, manufacturers provide limited information on their measurement performance. Therefore, we present a (to date) unprecedented comprehensive calibration study on three state-of-the-art digital anisotropic magnetoresistance magnetometers, to precisely determine various performance parameters and stability across different sensors of the same model. With the evaluation of sensitivity, noise, offset, and orientation determination, as well as considering dependencies on temperature and frequency, the performance of each sensor can be improved significantly, enabling their implementation in demanding fields of application (such as in satellites). Different measurement and calibration techniques, specifically aimed at the characteristics of the examined magnetometers, were utilized, using a sophisticated magnetic laboratory that has served as a calibration facility for several interplanetary space missions. Our study allows operators to decide whether to consider anisotropic magnetoresitance magnetometers for their application and, more importantly, to be able to (at least partially) skip a time-intensive and complicated calibration by using the sensor parameters given in this paper. To that end, the most promising sensor is recommended. The sensor examination suggests a good comparability of different sensors of the same model, and shows the importance of noise regarding the sensor performance with a noise floor up to 124 nT/Hz at 1 Hz. Additionally, depending on the sensor model, the sensitivity is 14 nT at best, and the attitude determination error can be reduced to about 0.3° with the given calibration.