An Approach to Model and Control a Flexible Spacecraft

In this paper, an easy and effective methodology to model flexible structures, such as a spacecraft with flexible appendages, is provided, which is valid also in the hypotheses of structures having varying cross-sections and of large deformations. For the above flexible structures, it is also proposed a method to easily design a simple and efficient control law, considering as design specifications the gain margin, the maximum tracking error, the maximum control signal, and the maximum terminal deflection of the flexible parts, assuming the reference generic but with bounded first derivative. Moreover, it is shown that the robustness of the control system is assured even though the design of the controller is made with a low-order model of the flexible structure. Finally, the proposed approach is illustrated and validated in the case of a satellite with flexible appendages, for various references.