Elimination of Parasitic Magnetic Interference over Magnetometer Data On board Nano-Satellites

摘要

This paper explains and compares the different methods that could be used to eliminate the effect of the leakage magnetic field on a magnetometer sensor on board on a 2U class Nano-satellite. Many operations conducted in the Attitude Determination and Control System [ADCS] use the values from the magnetometer, proving crucial to its controlling mechanism. The paper focuses on a magnetometer sensor used on board, specifically, an Anisotropic Magneto-Resistive [AMR] Magnetometer. The magnetometer experiences interference from various magnetically active components in the satellite, most of which can likely be eliminated by implementing a mathematical model for the calculated offsets. Although, the interference, from specific sources, like, the permanent magnet of the reaction wheel's Brushless Direct Current [BLDC] motor implemented in the ADCS system, is not constant. The paper depicts with a set of graphs, the possible nature of such disturbances. A robust explanation describing the methods adopted to quantify this variable interference over time, using a mathematical algorithm to compensate for the leakage magnetic field. The paper describes how the coefficients required for the algorithm can be deduced experimentally, with the required test setup. A system using magnetorquers as one of its actuators, requires an accurate supply of the live Earth's magnetic field from the on board controller along with the flux disturbances from the BLDC motor, for the effective conduct of its operation. Critical analysis of the given mathematical model and possible methods to deal with this problem are also provided.