Attitude Control Research Of Appendage Structure Spacecraft With Uncertain Inputs

As the development of aerospace engineering,spacecraft missions are becoming more and more diversified and complicated,so spacecraft need to install more and more sports attachments.During on-orbit service of the spacecraft,the limited control torques and the installation deviation of the actuator,can make the spacecraft inputs uncertain.At the same time,the interference of environmental torques,the coupling between attachments and main body,and the uncertainty of moment of inertia will seriously affect the attitude control precision of spacecraft.In this context,in this paper the status quo of spacecraft with attachments attitude control with uncertain inputs is analyzed,and take the basic two-rigid spacecraft as the research object to realize compound attitude control,where the spacecraft main body tracks orbital coordinate system and spacecraft attachment realizes spatial orientation.Firstly,the relative attitude movement models of the spacecraft main body and the attachment are established,and the target attitudes of the attitude tracking and the space pointing are settled.So the attitude tracking and the space pointing problems are transformed into the stability problems of the relative attitude.At the same time,considering the coupling and motion characteristics of the spacecraft with attachment,a new strategy to solve the coupling problem is proposed,which eliminates the effect of attachment coupling torques,replacing the traditional method of treating coupling torques as interference torques.Secondly,to realize the robustness of attitude tracking,in this paper the adaptive sliding mode control of spacecraft is designed.Firstly,the adaptive control algorithm based on angular velocity errors and quaternion errors is improved,and thus a simplified adaptive sliding mode control strategy is proposed for the spacecraft main body with moment of inertia uncertainty and disturbance torque.Then the control algorithm having universal applicability is designed to deal with the installation deviation.Finally,the adaptive control algorithm is designed to solve the attitude control problems with installation deviation,saturation,uncertain moment of inertia and disturbance torque.Considering the slow attitude change feature of orbital coordinate system,the small initial attitude errors and large uncertainty model are designed during the simulation to verify the effectiveness of the designed control algorithm.Finally,considering the demand of the fast maneuver pointing control,in this paper the finite-time control of spacecraft attachment is designed.Considering the uncertainties of moment of inertia and external disturbance torques of spacecraft attachment,the finite time control based on state observer is designed.Considering the condition with the installation deviation,saturation,the uncertain moment of inertia and the interference moment,the adaptive finite time control is designed.In the simulation large initial design errors are designed to verify the effectiveness of the designed control algorithm.