Autonomous Spacecraft Navigation Using Spacecraft-Spacecraft Network

Navigation is the key technique for deep space exploration.Nowadays spacecraft mainly obtains navigation information from ground measurement and control system,which suffers time delay and lay heavy burden on ground system.To reduce the heavy burden as well as increasing navigation efficiency for deep space explorers,a design of the autonomous navigation system for deep space explorers is of great importantance.The number of deep space explorers keeps increasing as space technology develops,which would form a vast interplanetary communication network of spacecraft.In this thesis,following aspects are studied.1?The concept of spacecraft-spacecraft network is described and a method of spacecraft autonomous navigation is proposed,also the application system is designed in the thesis.A state estimation method combining both whole network estimation and distributed network estimation is applied to estimate the state of spacecraft.An application scheme is designed specifically for earth to moon orbit transfer mission.Configuration and autonomous navigation for basis spacecraft is analyzed,and then the single-layer as well as multi-layer navigation scheme for customer spacecraft is elaborated.Simulation results show the feasibility of spacecraft navigation using spacecraft-spacecraft network.2?The error propagation mechanism of spacecraft-spacecraft network is studied.The error in spacecraft-spacecraft network can be divided into two types.One is the system error of x-ray pulsar based navigation for basis spacecraft,and the other is the positioning error the of upper-layer spacecraft,which leads to navigation error for customer spacecraft.For the first type of error,navigation based on time difference of pulsar signal can effectively reduce the system error of pulsars.For the second type of error,error propagation mechanism is analyzed by CADET,and the state extended method is used to compensate the upper-layer error.3?Configuration optimization of spacecraft-spacecraft network is researched.The observability of basis spacecraft and customer spacecraft is discussed to theoretically explain the feasibility of navigation based on spacecraft-spacecraft network.In order to improve the navigation precision of the basis spacecraft,a navigation accuracy analysis method based on Fisher information matrix is proposed.Different configurations of spacecraft are evaluated by Fisher information matrix.The optimal configuration can be determined and the navigation accuracy can thus be improved,and in this way the state estimation of the whole spacecraft-spacecraft network would be optimized to guarantee the high precision of state estimation.