Two-Dimensional Solution for the Analytical Extended Two-Step Magnetometer Calibration

Most marine, aerial, and land vehicle navigation applications employ magnetometers as part of their sensor fusion solution, mainly to provide the latter with a source of yaw/heading angle information. Before being used for such purposes though, magnetometers need to underpass a calibration procedure, so that eventual hard- and soft-iron magnetisms created by the vehicle itself and/or the embedded electronics/systems are suitably compensated for. Such a procedure usually requires the vehicle/sensor suit to be rotated around its three axes, which, sometimes, is unfeasible, due to the size/dynamic constraints of the latter. As a consequence, most of the state-of-the-art attitude-independent 3-D magnetometer calibration algorithms available in the literature will fail. As the main contribution of this article, we adapt a magnetometer calibration method proposed by the authors in a recent contribution, namely, the analytical extended two-step (AETS), to perform a 2-D magnetometer calibration successfully when the vehicle is able to rotate only around the yaw/heading axis. Results from simulated and experimental results are presented that demonstrate the superiority of the proposed 2D-AETS with respect to the aforementioned state-of-the-art 3-D magnetometer calibration techniques, in terms of: 1) accuracy; 2) immunity to convergence problems; and 3) easiness of implementation. The latter is shown to be true even when the vehicle is allowed to vary its roll and pitch angles (during calibration) inside a range of ±10° (a situation likely to occur in most marine, land, and aerial real navigation applications), and regardless of the noise level of the employed magnetometers.