Combined Spacecraft Mass Property Identification And Adaptive Attitude Control

With the development of science and technology,there are increadingly complex space missions in which in-orbit service task has received extensive attention of scholars at home and abroad since its high academic value and economic value.In many cases in-orbit spacecraft captures a non-cooperative target whose quality characteristics and motions are unknown,which brings huge challenges for the control system of a service spacecraft.Therefore the identification of quality characteristics of the combined spacecraft is a necessary prmise for control task.Space manipulators are regarded as the most valuable in-orbit service technology.Based on the backgraound of in-orbit dervice missions,this thesis focuses on the quality characteristics identification of the combined spacecraft and the adaptive attitude control.The main research contents of this thesis include:To solve the quality characteristics identification of a combined spacecraft with a space manipulator system,necessary coordinate systems are established,reasonable assumptions are given,and the research problems are abstracted and clarified.Form an attitude dynamics model using Modified Rodrigues Parameter method obtaining the explicit relationship between the identification deviation and the controller.Determine the quality characteristics identification scheme and transform the parameter identification problem into an optimization problem.After the discriminability analysis,the global optimal solution is obtained using a optimization algorithm.To solve the atiitude control of a combined spacecraft system,considering the possible uncertainty of a combined spacecraft system caused by the identification deviation or the non-ideal space environment,this thesis designs an adaptive PD control law using RBF neural network based on the relationship between the identification deviation and the controller given by Chapter 2.In view of the insufficiency in the former algorithm,an improved adaptive sliding mode control law is given.Finally a simulation verities the effectiveness of these two control laws.To solve the attitude adaptive control problem considering state constraints,starting from two aspects of control command and control law,that is,an S-Function curve replaces the step signal based on the idea of trajectory planning of the robot smooth drive and Barrier Lyapunov Function introduces parameters for state constraint in the control law.The simulation results show that both methods have achieved the purpose of improvement of control effect.