| The larger and more complicated structure of satellite has become an inevitable trend with the diversity of the demand of space mission. In order to maintain long-term life and complete the mission quickly, installation of numerous functional appendages on the satellite is necessary, and the application of large flexible space truss structure is more and more widely. The negative effects caused by the vibration of flexible appendages and the rigid flexible coupling effect of appendages and the satellite body of on-orbit satellite are urgent issues need to be considered. As few literatures has specialized for the attitude control problem of flexible satellite with intelligent truss structure, in this paper, in view of the vibration suppression and the attitude stabilization control problem of intelligent truss satellite, we made the following research:Firstly, common coordinates needed when establish the attitude model of satellite are introduced, then the finite element equations of space intelligent truss structure ignoring the rigid flexible coupling effect is given. Finally the kinematical equations and the dynamic model of the flexible satellite with multi fixed intelligent truss are given.Considering that the source of vibration response of intelligent truss satellite is the flexible vibration of intelligent truss structure, the vibration control problem of satellite has been equivalent to the vibration suppression problem of truss structure, and two kinds of finite time vibration suppression controllers based on Independent Modal Space Control theory are designed. Firstly, without considering the rigid flexible coupling effect, taking the coordinate transformation of sates achieved by modal filter and the real-time estimation of total system interference achieved by Extended State Observer in account, a finite time controller based on homogeneous method is designed according to the model which is simplified by the idea of ‘linearization with dynamic compensation’. Furthermore, in order to enhance the strong robustness for parameter perturbation and disturbance of the control system, a terminal sliding mode adaptive finite time controller which combined with double power reaching law is designed considering the disturbance with unknown upper bound. Simulation results show that both of the designed controllers can suppress the vibration response of the intelligent truss satellite effectively in finite time, and the terminal sliding mode controller has the characteristics of higher precision, faster convergence speed of flexible vibration and stronger robustness.In the condition that the intelligent truss is relatively fixed to the rigid satellite body, for attitude control of intelligent truss satellite in the presence of external disturbance, two different attitude stabilization controllers are designed. Firstly, estimation information of unknown disturbance is given by a nonlinear disturbance observer, and the modal acceleration information of truss and angular acceleration information of satellite are given by a super-twisting observer. Secondly, the terminal sliding mode controller designed in the last chapter is reformed by adding the rigid flexible coupling terms. Finally, in order to realize the stabilization control of intelligent truss satellite, a nonlinear predictive controller without requirement of precise system model and a terminal sliding mode controller with finite time convergence property are designed. Simulation results show that both of the designed controllers can stabilize the attitude of the intelligent truss satellite in finite time and suppress the vibration effectively. |
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