Magnetic Attitude Determination and Control of Small Spinning Spacecraft

An attitude determination and control system for small spinning spacecraft based only on a threeaxis magnetometer and magnetic coils is proposed. The pointing error components, namely roll and yaw angles, are estimated in an Extended Kalman Filter, making use only of magnetometer data. The coarse Sun direction estimation provided by body mounted solar panels, is used to improve the filter convergence rate. The control law provides spin-axis pointing, spin rate regulation, as well as nutation damping. The pointing accuracy obtained by this system is on the order of one degree, which is often suitable for small missions. For missions requiring better pointing accuracy, this system can be used as a backup in case of failure of the primary pointing error detection system. Contrary to previous implemented methods, this algorithm does not make use of a dedicated sensor to estimate the pointing error and does not require nutation dampers, thus reducing on-board hardware.