ATTITUDE ESTIMATION OF A NEAR-EARTH SATELLITE USING MAGNETOMETER DATA

The attitude of a near-Earth satellite is determined using only accura tely observed magnetic field vector data from three-axis measurements. Solving the equations of motion, the behaviour of the satellite aroun d the magnetic field vector is established, while the attitude is prop agated from the changes of the geomagnetic field along the orbital tra ce. An algorithm in which both the dynamic and kinematic equations of motion are integrated minimizes through a batch filter technique the e stimated magnetic field components with the observed components. The a ccuracy of the method depends on the external and internal model's tor ques considered. Two versions were developed, one with the Euler angle s parameterization and the other, less expensive in terms of computati onal time, in quaternion representation. The initial values of the sol utions and some other dynamic state elements are estimated from the mi nimization procedure based on the gradient method. This method has bee n applied for two magnetically stabilized mini-subsatellites which ope rated in near-polar orbits. (C) 1998 Published by Elsevier Science Ltd .