A method of determining attitude from magnetometer data only
Abstract
Presented here is a new algorithm to determine attitude using only magnetometer data under the following conditions: (1) internal torques are known and (2) external torques are negligible. Torquefree rotation of a spacecraft in thruster firing acquisition phase and its magnetic despin in the Bdot mode give typical examples of such situations. A simple analytical formula has been derived in the limiting case of a spacecraft rotating with constant angular velocity. The formula has been tested using lowfrequency telemetry data for the Earth Radiation Budget Satellite (ERBS) under normal conditions. Observed small oscillation of bodyfixed components of the angular velocity vector near their mean values result in relatively minor errors of approximately 5 degrees. More significant errors come from processing digital magnetometer data. Higher resolution of digitized magnetometer measurements would significantly improve the accuracy of this deterministic scheme. Tests of the general version of the developed algorithm for a freerotating spacecraft and for the Bdot mode are in progress.
 Publication:

Flight Mechanics/Estimation Theory Symposium, 1990
 Pub Date:
 December 1990
 Bibcode:
 1990fmet.symp..359N
 Keywords:

 Attitude (Inclination);
 Magnetic Fields;
 Magnetometers;
 Rotation;
 Scientific Satellites;
 Telemetry;
 Algorithms;
 Angular Velocity;
 Digital Data;
 Earth Radiation Budget;
 Errors;
 Low Frequencies;
 Oscillations;
 Torque;
 Astrodynamics