Autonomous Orbit Determination Of Emergent Spacecraft Based On Space-Based Navigation Data

Quick orbit determination is the precondition of the application of space system.Recently,emergent space mission has developed gradually and it has many special features,such as strong provisionality,slow preparing time and quick application.These put heavy pressure on the assignment of ground measurement and control systems.In addition,the battlefield environment imperils the survival of ground support systems.Consequently,all of these make it difficult to determine the orbit of emergent spacecraft and finally influence the implement of emergent space mission.So,it is necessary to develop autonomous orbit determination technique that can be carried out without the support of ground systems.This dissertation analyses the orbit extrapolation model and applies it to ephemeris determination of spacecraft and fault detection of navigation data with the help of space-based navigation equipment.Firstly,the physical meaning and features of the Two Line Elements(TLE)regularly released by North American Aerospace Defense Command(NORAD)are analyzed systematically.The periodic items are being removed with unique method and so TLEs are“mean”orbit elements which can only be used with Simplified General Perturbation or Simplified Deep-space Perturbation model(SGP/SDP)to propagate the orbit status.Since the object of this dissertation is the low-orbit emergent space mission,Simplified General Perturbation Version 4 model(SGP4)fits it best.Apart from these,the SGP4 model uses the True Equator and Mean Equinox of Date Coordinate System(TEMED),so the relationships among TEMED,J2000 and World Geodetic System 84(WGS84)are also derived.Further,since NORAD does not promulgate the procedure of removing and reconstructing the periodic items,this dissertation regards the ephemeris determination as a“Black-Box”problem and introduces reverse algorithms which use outputs to compute inputs to determine the TLEs.The Iteration Algorithm based on single navigation data and Extended Kalman Filter(EKF)and Unscented Kalman Filter(UKF)Algorithms based on multiple navigation data are proposed to compute the spacecraft ephemeris.The simulation results with tle-00005 satellite show that all algorithms are valid and of high accuracy,and they are all able to meet the precision of standard TLE format.Finally,fault detection algorithms of navigation data are proposed.Because the validity of navigation data influences the validity and precision of ephemeris determination algorithms,so this dissertation proposes State ?~2 and Residual Error ?~2 Fault Detection Algorithms to detect data validity.Simulation results show that these algorithms are valid in detecting mutation and gradient fault of navigation data.To sum up,this dissertation studies the autonomous orbit determination of emergent spacecraft.Based on SGP4 orbit propagation model and space-based navigation data,Iteration Algorithm and Kalman Filter Algorithm are designed to compute spacecraft ephemeris while ?~2 Fault Detection Algorithm is proposed to detect navigation data fault,which hold reference value for future emergent space missions design.