The magnetometer is one of the most suitable attitude sensors for almost all low earth orbit (LEO) satellites.
There have been lots of efforts to develop attitude estimation algorithms using only a magnetometer and a spacecraft attitude estimation algorithm utilizing only magnetometer readings was developed. Although the algorithm can provide high accuracy of satellite attitude estimation, it is widely known that the unscented Kalman filter (UKF) faces heavy computational load.
Kim Hak Min, a researcher at the Faculty of Aerospace Engineering, proposed an attitude and angular rate estimation algorithm based on quaternion estimation (QUEST) and unscented Kalman filter (UKF).
The proposed algorithm uses only three-axis magnetometer as an attitude sensor and works in two stages. In the first stage, the QUEST uses magnetometer measurement vector and its derivative to estimate a coarse attitude. In the second stage, these estimated values are used as quaternion measurement data for UKF processing. The state vector for UKF consists of attitude parameters and angular rate vector. As a result, it is possible to estimate satellite attitude and get angular rate with high accuracy and small computation load.
The simulation result showed that the attitude of a satellite can be estimated with higher accuracy than 0.2° with small computational load.
You can find the details in his paper “Research on LEO Satellite Attitude Estimation Based on Quaternion and Unscented Kalman Filter” in “Proceedings of KUTIC-2025”.