Autonomous Navigation of MegSat1: Attitude, Sensor Bias and Scale Factor Estimation by EKF and Magnetometer-Only Measurement

In this paper we present the first stage of the study of the attitude estimation by magnetometer-only measurement and self-compensation of sensor bias and scale factor drift, concerning the autonomous navigation the low cost orbiting microsatellite MegSat1. A three-axial magnetometer is used with the Extended Kalman Filter (EKF) with local iterations to estimate 3D angular velocity and attitude of the space vehicle, in addition the sensor bias and scale factors are on-line estimated in order to enhance the reliability of the estimation process. Using simulated data the filter has been tuned: with only bias drift estimation true state can be reached starting from an attitude error of 60 deg without knowledge of angular velocity; with both bias ed scale factors drift true angular rate, bias and scale factors drift can be estimated starting from initial angular error of 30 deg, while attitude estimation demonstrates periodic behavior. This work suggests that sensor scale factors drift represents the most important metrological characteristic of magnetometer for attitude estimation. Copyright © 2004 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.