LAUSR

Abstract A new type of earth observation mission using a spacecraft with rotational payload is introduced in this paper. The kinematic and dynamic equations for the nadir-aligned attitude tracking problem are derived in the presence of a misaligned rotational payload. A quaternion-based feedback control law is proposed and its stability is analyzed using the Lyapunov direct method. Comparisons are made between the simulation results of the proposed control law and that of a conventional PD feedback control law. The analytical solution of the spacecraft's residue angular momentum is obtained. Monte Carlo analyses are employed to demonstrate the angular rate accuracy of the system and to study the effects caused by the knowledge error of parallel misalignment. Simulation results show that the angular rate accuracy improves greatly by the proposed control law.