Large spacecrafts, such as Astronomy Observation Satellite or International Space Station docked with manned or cargo spaceship, are complex ones composed with multiple rigid and multiple flexible bodies. The rotation of the onboard expanded limbs, manipulators or solar panels with respect to the spacecraft platform would change the composite spacecraft's attitude, centroidal coordinate and moment of inertia, and would induce disturbance to the attitude control system of the spacecraft as well. To guarantee the pointing accuracy, the precise inertial parameters should be determined and perfect attitude control algorithm should be designed. In this paper, According to Moment of Momentum Theorem, a double rigid-body dynamic model was formulated, which could be used to determine the inertial tensor of the complex spacecraft system. Quasi Euler Angles are introduced to describe the attitude of the spacecraft. Considering the flexibility of the flexible parts, a trap filter is employed to depress the noises that have an approximate frequency with the fundamental frequency of the flexible parts of the spacecraft. The output of 3-D modeling software indicated that the double rigid-body dynamic model is perfect and Simulation results indicate that the attitude control scheme is effective.
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