Robust active vibration suppression of a nonlinear flexible spacecraft

In this paper, attitude control and active vibration suppression of flexible spacecraft using piezoelectric patches as actuator and sensor is considered. Two inner and outer loop controllers are used (inner loop for controlling panel vibration and outer loop for controlling spacecraft attitude). Piezo patches and reaction wheel are used as inner and outer loop actuator respectively. In inner loop an optimal controller has been designed for suppression of panel vibration. In outer loop, two controller feedback linearization and composite controller (combine of feedback linearization and mu-synthesis) act on rigid hub to perform spacecraft maneuver. To evaluate the performance of the proposed controllers, an extensive number of simulations on a nonlinear model of the flexible spacecraft are performed. The performances of the proposed controllers are compared in terms of nominal performance, robustness to uncertainties, panel vibration suppression, sensitivity to measurement noise, environment disturbance and nonlinearity in large maneuvers. Simulation results confirm the ability of the active controller in tracking the attitude trajectory while damping the panel vibration. It is also verified that the perturbations, environment disturbances and measurement errors have only slight effects on the tracking and damping performances in the composite method.