Fault Tolerant Control Design On A Class Ofspacecraft Formation With VaryingDimension

This paper mainly studies the design of fault tolerant control of a class of spacecraft formation with varying dimension, currently, spacecraft formation flying(SSF) is a hot topic in the field of aeronautics and astronautics, no matter for the military or civilian purpose, only a single formation can not meet the increasing complex space tasks. For completing special space task, the spacecraft(s) in the formation may dock, separate, depart and participate to change the formation for the adaptation of tasks. Take each formation as a mode of the spacecraft formation system, with the method of multiple Lyapunov and dwell-time of switched system, we can analyze and study the stability of the systems that are system with all stable modes and system which has unstable modes and verify the feasibility of the provided method through the Matlab simulation.Firstly, the concept of spacecraft formation flying and switched system are introduced, and describe the relation, backgrounds and meaning between them, summarize the fault types that influence the spacecraft formation flying and the fault tolerant control methods, conclude the present situation of the study of spacecraft formation flying.Secondly, several coordinate systems which are commonly used are presented. Use the method of quaternion to describe the attitude of spacecraft, and analyze the relative motion between spacecrafts from the perspective of their kinematics and dynamics. In the light of a class of spacecraft formation flying with varying dimension, the whole formation can be seen as a system, and the states of system is the motion and attitude errors of each spacecraft relative to reference coordinate points. Then establish a formation flying model under the general case, analyze the stability of the system and construct a basis of the next content of study the stability of the three kinds of systems that are system with all stable modes, system with unstable modes and system with all unstable modes.Thirdly, based on the general model, consider the case that the states may jump at the switching instant in the system with all stable modes, with the effect on the system stability, it can be converted into the study of stability and fault tolerant control of the impulsive switched formation system; for the system with unstable modes, with the help of the dwell time method of the switched system, regulating the ratio of activating time between stable modes and unstable ones to compensate the unstable influence and achieve the stability of the system.Finally, by the Matlab platform, the simulation of the formation system with impulsive switched system in all stable modes and the one that have unstable modes are conducted, the proposed method is proved to be correct and reasonable through the result of the simulation.