Attitude Independent Magnetometer Calibration Considering Magnetic Torquer Coupling Effect

T HREE-AXIS magnetometer (henceforth TAM) is widely used as a component of spacecraft attitude sensors. During the launch and on-orbit period, TAM is affected by mechanical distortion, thermal gradients, and internal magnetic moment disturbance of magnetic actuator. The typical purpose of calibration is to estimate factors that affect raw measurements in the magnetometer frame. Over the past several years, many studies have been conducted pertaining to attitude-independent calibration [1–3]. Generally, these studies were focused on the computation of calibration parameters without including magnetic torquer (MTQ) coupling effect. However, as an example, TAM measurement was found to be contaminated by MTQ activation according to the first Korea Multipurpose Satellite (KOMPSAT-1) flight data. If the several preceding methods take KOMPSAT-1 TAM data, the outcome could be an incorrect calibration. In this study, the proposed calibration method can estimate theMTQcoupling effect togetherwith bias, scale factor, and nonorthogonality terms. The particle swarm optimization (PSO) algorithm is used to estimate 18 calibration parameters. The PSO algorithm is known to be a powerful algorithm that searches for a solution to minimize nonlinear cost functions with a simple structure for computer implementation [4].