Active vibration suppression of flexible spacecraft based on dynamic output feedback

A dynamic controller is presented for rest-to-rest flexible spacecraft attitude maneuver with the active vibration suppression. On the basis of the Lagrangian approach and quaternion parameterization, the nonlinear model of the flexible spacecraft is obtained. This controller does not need the knowledge of modal variables and spacecraft angular velocity. The unavailable measurements of these variables are compensated by appropriate dynamics of the controller, which supplies their estimates. The Lyapunov technique is applied to design this dynamic controller, that ensures the stability of the system. Possible source of instability of the controlled system in real cases are the influence of the flexibility on the rigid motion and the presence of disturbances acting on the structure. In order to attenuate their effects and to damp out the undesirable vibrations affecting the spacecraft attitude, distributed piezoelectric actuators are employed. The simulation results reveal the interest and the practical feasibility of such a control scheme.