| Nowadays the structure of the satellite is becoming more complex and moreappendages have been installed on the satellite. In order to obtain high precision andhigh stability attitude control performance, problems caused by vibration and rotation offlexible appendages must be attached importance. This dissertation mainly studies theattitude control problems of satellites with flexible solar arrays and rotatable antennas.The works completed are as follows.Firstly, common coordinate and Euler angle description are introduced andkinematical equations are given. The attitude dynamic model of satellite with two solararrays and one rotatable antenna is established based on the hybrid coordinate method.According to the robust theory, two attitude control method are proposed for thevibration suppression problem of the flexible arrays. Frequency domain method is usedin the process of design and the design goal is to reduce the frequency response fromdisturbance to angular velocity. First, the model is simplified by regarding the influenceof flexible modal as disturbance. The PD controller and a compensator are designed,and the performance of the compensator is analyzed and proved to be effective. Second,turn the influence of flexible modal into multiplicative uncertainties. The robustcontroller is designed with mixed sensitivity method. The simulation result shows thatvibration is suppressed effectively and the system is robust under the influence ofdisturbances and uncertainties.Controllers are designed to deal with the problem brought by the rotation of theantenna. The influence of the stability caused by the antenna is analyzed. The global,RBF neural network and backstepping sliding mode controller are investigated based onsliding mode control theory. Moreover, the feedforward is added. It turns out that theabove method accomplished the attitude control mission, and precision and stability ofthe system have achieved the anticipated requirements. |
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