Combined attitude control of small satellite using one flywheel and magnetic torquers

A combined attitude stabilization control method is proposed on the bases of using both flywheel and magnetic torquers in case of flywheel failures. Firstly, a combined control scheme is provided with control allocation loop, and the control allocation and magnetic unload algorithms are further developed. Considering a specified condition when only the pitch axis flywheel is available, a strategy is proposed to alter the reaction wheel to a momentum wheel while keeping the satellite stable from generated disturbances using magnetic torquers, then combined with three-axis magnetic torquers to stabilize satellite to nadir pointing. Numerical simulations demonstrate the proposed technique can dynamically achieve failure isolation system reconfiguration, and can also finish the high accuracy attitude control task of small satellite. It also prolongs life of space task. Another point is its excellent robustness, simple design, and real time calculation on-board.