Research On High-Precision Relative Navigation And Keeping Control Method For Satellites Formation Flying With Continuous Low-Thrust

The space application of spacecraft has been changed to network,and research of formation flight is one of the representative directions.By using multiple satellites to work together in a certain formation configuration,it can not only realize traditional function but also accomplish the tasks which are difficult to achieve by single satellite.Meanwhile,it can reduce the risk and cost of the system.High precision of relative state determination and configuration control is required for the special tasks,such as synthetic aperture imaging and astronomical observation.However,due to the influence of perturbation,the relative position between the spacecraft is changing and uncertain.Therefore,it is required to solve the key technology of relative navigation and formation keeping control.In this paper,a high precision relative navigation method and accurate formation keeping control method is studied based on the continuous low thrust control.Firstly,based on the satellite formation flight system,relative dynamics for formation satellites is studied,and the J2 term is introduced.At the same time,the GPS carrier phase difference(CDGPS)model is established.Secondly,considering the high-fidelity J2 equations,an on-line identification model of thrust acceleration is explored via the estimated acceleration of major space perturbation and the inter-satellite relative states obtained from spaceborne acceleration sensors.So the thrust identification method can reconstruct the continuous low thrust acceleration.A modified EKF based on the on-line identification of the thrust is proposed to estimate the relative state of the formation satellites.Simulation results show that the modified EKF method can accurately compensate the thrust acceleration,and achieve high precision position results.Thirdly,an adaptive continuous control method with bounded output for satellite formation flight is proposed.The adaptive closed-loop feedback control law is designed.The simulation results are performed to verify the effectiveness and superiority of the proposed controller.Finally,using RT-LAB software,a distributed simulation platform for a satellite formation flying control system is constructed.Through hardware-in-the-loop simulation,the relative navigation method based on continuous low thrust identification and the adaptive continuous control method with bounded output are verified useful for theory and engineering.