Attitude Maneuver Control For Flexible Spacecraft Under Angle Velocity Constraint

In some space missions, it is required that the orbiting spacecrafts accomplish quick attitude maneuver tasks within the scope of attitude sensors' work zone. But unfortunately the sensors can only work in a bounded angular velocity range, meanwhile, to fulfill the missions such as taking pictures and investigations, the angular velocity of the spacecraft can not be too large. Thus the angular velocity constraint is one of the most important problems in the spacecraft maneuver control. There are many large flexible accessories on modern spacecraft, the stretch and oscillation of the flexible structures will change moment inertia of the spacecraft and thus the exiting of parameter uncertainties, so some measurements must be taken to suppress the vibration of flexile structures. The orbiting spacecraft in space is usually disturbed by various external disturbances. Due to the problems mentioned above, this thesis mainly aims at deeply studying the flexible spacecraft attitude maneuver under angular velocity constraint. The main contents are described as follows.First, the kinematics and dynamics mode of flexible spacecraft are established according to relevant principles and related literatures. A brief review about the relevant knowledge of stability is given, and then the problem of angular velocity is presented, afterwards establish the foundation for the controller design and analysis of the following section.Secondly, in order to reduce the difficulty of designing the controllers for flexible spacecraft, the flexible spacecraft is treated as an associate rigid. In this case, two controllers are designed: The first one is designed under the condition with known moment of inertia. The other one is designed when there is parametric uncertainty in the moment of inertia. Through the simulation results, both controllers can guarantee the angular velocity constraints during attitude maneuver and the stability of the closed-loop system. It should be noted that this simplified treatment can only be adapted where the flexible modal amplitude is small. Larger modal amplitude will cause system to produce oscillations.Finally, in order to guarantee the performance of the system when the flexible modal amplitude is large and a observer for the estimate of flexible mode is designed This section also divided into two conditions without/with parametric uncertainties in flexible spacecraft, the controllers are designed to restrain the large amplitude of flexible when the vibration modal is stirred up and have strong robustness to uncertain parameters. We verify the feasibility and effectiveness of the proposed controller through the MATLAB simulation.