Orbit Maintenance And Reconfiguration For Spacecraft Cluster Flight

With the development of space technology,more and more space missions can not be accomplished by a single spacecraft or traditional spacecraft formation flying.Spacecraft cluster flight,which is a novel coorperative multi-spacecraft flight mode,has become an important research direction of distributed space system for the future.This dissertation mainly concentrates on the systemically study of initial orbit design method,long-term bounded maintenance control and rapid flexible reconfiguration maneuver strategy.The main research work and results are as follows:(1)Relative motion models for spacecraft cluster flight are studied.Firstly,the relative motion model and control model are established by relative orbital elements,and the influence of J2 perturbation on relative orbital elements and relative motion is analysed.Secondly,the concept of spacecraft period-delayed errors is introduced,and by combining with a high-fidelity linearized J2 model,the spacecraft cluster flight dynamics model based on period-delayed errors consensus is established.(2)The performances of cluster and the optimal initial orbits design method based on relative orbital elements are studied.Firstly,the cluster flight passive safety and maximum relative distance requirements are described in terms of relative orbital elements.Then,through the analysis of cluster member state description,state transitions and cluster drift,the stability of cluster is discussed.Next,based on the defination of optimal packing and scalability problems,the flexibility of cluster is discussed.Numerical simulation results compare the strengths and weaknesses of 4 typical cluster initial configurations in the indicators such as stability,optimal packing,and scalability of the cluster.Moreover,a graphical optimal initial orbit design method for cluster flight is developed,and the obtained initial states can be used as initial conditions of cluster maintenance control.(3)The maintenance control method based on relative orbital elements is studied.Firstly,a novel spacecraft cluster feedback control method with control box is analyzed.Then,two functions for choosing maneuvering satellites are proposed and two maneuver strategies when constraints are not astisfied are designed.Next,an optimal three-maneuver strategy is developed which could obtain the optimal manuver value and time.Finally,the feasibility and effectiveness of the optimal maintenance control method are verified through numerical simulations under the background of NetSat project.(4)The optimal maintenance control method based on period-delayed errors consensus is studied.Combining graph theory,consensus theory,energy matching principle and the cluster period-delayed errors dynamics model,an optimal control law with coupling gain and feedback control gain matrix is designed.Then,the consensus problem of spacecraft cluster is converted into the stability of a set of matrices with the same dimension,which could reduce the computational complexity significantly.Finally,by using an energy matching condition as the initial condition,the feasibility and effectiveness of the optimal maintenance control method for spacecraft cluster flight are verified through numerical simulations.(5)Spacecraft cluster flight reconfiguration manuver strategy based on modified simulated annealing algorithem is studied.Firstly,a modified simulated annealing algorithem is proposed,which could increase the convergence speed,comparing with the traditional simulated annealing algorithm.Then,spacecraft cluster flight reconfiguration manuever missions are described,and the reason why modified simulated annealing algorithem is choosed as the optimization methoed is analysed.Next,a spacecraft cluster flight reconfiguration manuver strategy is designed,by combining spacecraft cluster flight reconfiguration manuever missions and the modified simulated annealing algorithem.Finally,the proposed cluster reconfiguration manuever strategy is applied to a cluster scatter/regather mission in numerical simulations,thereby the effectiveness and rapidity are verified.