Research On Dynamics And Control Of The Cislunar Spacecraft Formation Flying

Cislunar space is the region which is effected by the earth and the moon’s gravity.Two-body dynamics can’t describe the motion of satellite in the cislunar space accurate.Cislunar spacecraft formation flying technology has huge potential application while the development of micro-satellite and formation flying technology.Some problems has been analysed,including the modeling of satellite formation in cislunar space,the evolution of formation configuration with non-closed and aperiodic orbit,and formation keeping and control method in earth-moon system.Dynamics and control of the cislunar spacecraft formation flying are studied in this dissertation.Based on the three-body formation dynamics,the modeling of relative motion for cislunar spacecraft formation is developed with normalization and linearization.Through this model and theoretical derivation of state-transition matrix,the similarity characters of cislunar spacecraft formation dynamics are studied.Though the inverse time dimension integration method,the orbit from the moon to the lagrange point L2 is designed as a nominal orbit.According to the nominal orbit,three types of formation configurations are designed including the following flying formation,the accompanying flying formation and the linear formation.In addition,a quality factor of straightness are designed at the same time.Through numerical simulation of free flying,the relative conclusion is validated and the evolution of formation configuration for free flying is analysed.The control algorithm for cislunar spacecraft formation keeping problem is investigated.Utilizing linear quadratic optimal theory to build the LQR controller and the Lyapunov stability theory is used to prove the asymptotical convergence of system states.To improve the LQR controller,a control strategy is designed on the base of feedforward-feedback control theory.A simulation is carried out to indicate that both methods are effective with comparison which shows the feedforward-feedback control algorithm has higher precision.The control algorithm for cislunar spacecraft formation maneuvering problem is investigated.Maneuvering control missions are divided into two parties,including formation reconfiguration problem and trajectory tracking problem.It is discussed that the control strategies of formation keeping problem are suitable for formation reconfiguration problem.Through numerical simulation of a baseline reconfiguration task,the effectiveness of the strategies is validated.And the results show the feedforward-feedback control algorithm has higher precision.Focusing on the problem of trajectory tracking,a feedforward-feedback controller is designed again.Through numerical simulation of a fly-around task,the effectiveness of the strategies is validated.In summary,through theoretical analysis and numerical simulation,the dissertation analyses the model and formation and studies the dynamics and control method of the cislunar spacecraft formation flying.And some conclusions and strategies are validated.It can provide the technical basis for the cislunar spacecraft formation,and has reference for micro-satellite formation and satellite formation tasks for deep space exploration.