Attitude manoeuvring and vibration reducing control of flexible spacecraft using smart materials

The question of robust attitude control and vibration reduction of flexible spacecraft during manoeuvre is considered. The design approach presented here treats the problem of spacecraft attitude control separately from the elastic vibration suppression, by designing a dynamic controller, using attitude measures alone for desired attitude rotation and smart materials for active vibration suppression. The proposed attitude controller does not need the knowledge of modal variables and spacecraft angular velocity, which is compensated by appropriate dynamics of the controller. For actively suppressing the vibrations introduced to the flexible appendages, embedded piezoelectric ceramic patches are used as both sensors and actuators, to detect and counter-react the induced vibration during and after the manoeuvre. Here, a modified positive position feedback (PPF) control strategy, targeting at the first three flexible modes of the flexible spacecraft is taken into account. The performances of this approach are assessed in terms of the level of vibration reduction at resonance modes and the speed of response. For comparison, the proportional plus derivative control strategy is adopted and compared with proposed control approach. Simulation results demonstrate the effectiveness of the controller design strategy for attitude control and the modified PPF compensators for active vibration suppression.