Two-level orientation control system of flexible spacecraft with active stabilization of structural elastic oscillations

Active stabilization of the elastic oscillations of the flexible objects belonging to the class of flexible spacecraft (FSC) was shown to be required for stable orientation control in addition to the main goal of control. An algorithm of Kalman estimation of the FSC coordinates and parameters was constructed, and a principle was proposed for two-level orientation control based on realtime estimates of the controlled coordinates. At that, the first level of control orients the FSC by the estimated “rigid” component of the total motion, and the second level stabilizes its structural elastic oscillations using the estimated elastic modes as controls. A number of algorithms was proposed to actively damp the elastic oscillations, and the methods of mathematical modeling were used to prove that in the case of two-level control the combined FSC motion is a stable manifold closed in a bounded domain where the requirements on the desired dynamics of FSC orientation processes are satisfied.