Abstract: The problem of robust attitude control for three-axial-stabilized flexible spacecraft is considered. The inverse transfer function matrix of attitude dynamics is derived from the hybrid coordinates equations, and its normality is analyzed. Based on the results, a normal matrix design approach for spacecraft attitude control systems is developed by using a feedback perturbation description for system uncertainties. The results show that the inverse transfer function matrix is a normal matrix, and this fact is independent of the spacecraft dynamical parameters. Based on the normality nature, the normal matrix design approach for spacecraft attitude control is developed. With the proposed method, the robust control of spacecraft attitude can be achieved by a parameter constraint on the three-axis control loops of attitudes, thus the attention can be focused on the performance promotion and therefore the proposed method is more practical. The simulation results show the effectiveness of the proposed approach.

Key words: spacecraft, attitude control, robust control, normal matrix, feedback perturbation