ESA GNC Conference Papers Repository

Based on magnetometer measurements only, three-axis attitude, rate and orbit estimation is successfully achieved. A single Augmented Dynamics Extended Kalman Filter (ADEKF) is configured by combining the spacecraft nonlinear dynamics, quaternion kinematics with orbital dynamics. The filter design is adopted for three-axis stabilized spacecraft in low Earth orbits where the aerodynamic drag is the dominant source of disturbances in addition to the spacecraft residual magnetic. To reduce the computational burden, another Interlaced Extended Kalman Filter (IEKF) is developed to uncouple the attitude/rate and orbit dynamics. Both filters are implemented using the magnetometer measurements and their corresponding time derivatives. As a part of EgyptSat-1 flight scenario, detumbling and standby modes are used for performance testing of the ADEKF. The stability of the filter is investigated by incorporating extensive Monte Carlo simulations with uniformly distributed initial conditions. The filter has shown the capability of estimating the attitude better than 5 deg and rate of order 0.03 deg/sec in each axis. In orbit estimation, the filter is capable of estimating the position with accuracy less than 8 km in each axis.