Research On Attitude Maneuver And Tracking For Flexible Spacecraft

In order to complete a variety of space missions, such as satellite formationflying, on-orbit maintenance, the spacecraft is often required to complete largeangle attitude maneuver or attitude tracking. As the task performed by spacecraft isbecoming more and more complex, the equipments carried by spacecraft, such assolar panels or detection camera, have increasingly diversified. Due to the vibrationof the flexible appendage, fuel consumption, external disturbances such as gravitygradient torque, the attitude system of orbiting spacecraft becomes a nonlinearsystem with parameter uncertainties and external disturbances, sometimes withactuator saturation. The adverse impact of these factors on the attitude controlsystem of spacecraft must be considered. The present dissertation mainly focuses onlarge angle maneuver and attitude tracking of the flexible spacecraft. The mainresearches are presented as follows.First, two kinds of attitude kinematics of flexible spacecraft described by Eulerangle and unit quaternion are established and analyzed. In order to design thecontroller for the flexible spacecraft, we choose the second method to describe theattitude of spacecraft. Then the dynamics model of the flexible spacecraft isestablished.Then, an adaptive backstepping control scheme is developed for large angleattitude maneuver of flexible spacecraft subject to uncertain inertia parameters andexternal disturbances. The results of numerical simulations show that the flexiblespacecraft can reach the desired attitude fast and also verify the controllerrobustness against parameter uncertainties and external disturbances.Finally, we focus on the attitude tracking of flexible spacecraft withoutactuator saturations. An adaptive backstepping controller is designed and theperformance of the controller is verified by numerical simulation. After that, byintroducing an auxiliary vector to compensate the error of desired control torqueand real control torque, a novel anti-windup attitude tracking control scheme isdeveloped for flexible spacecraft subject to actuator saturations. The results ofnumerical simulation show that the anti-windup attitude tracking controller can dealwith the problem of actuator saturation, effectively.