Agile and precise attitude maneuver of flexible spacecraft based on nonstationary frequency-shaped robust control

The recent need for more flexible spacecrafts requires more agile and precise attitude maneuver. To meet this requirement, their controller must be robust against high-frequency unmodelled uncertainty and be able to have a greater range of motion and vibration control. The attitude controller for these more flexible spacecrafts described in this paper is designed with a nonstationary frequency-shaped robust control that is based on the differential game theory. The weightings of the proposed controller are designed to envelop the highfrequency unmodelled uncertainty and to enable the controller to suppress any spillover instability. The proposed controller generates optimal input torques to control the agile and precise attitude maneuver of a spacecraft by using the weightings of the state vector, which are designed in the time domain. In addition, the controller has a robust performance against parameter errors by using the weightings designed in the frequency domain. Several simulation results proved the effectiveness of the proposed controller.