Autonomous Navigation For Two Satellites Based On Relative Position Measurements

The autonomous orbit determination of satellites is one of the core technologies for modern satellite's operations.With the birth of such concepts as satellite constellations,formations,and clusters,autonomous navigation with using inter-satellite measurements has become an important topic.In this paper,the method of autonomous navigation using the inter-satellite position vector is studied for the two satellites' system which are operating on the lunar elliptical orbit.The main work is as follows:Because there is a great difference between the lunar environment and the Earth.Firstly,this paper studies the calculation of the lunar coordinate system and its relationship of transformation.And a dynamic equation that takes into account the main perturbations of the lunar satellite has been established under the IAU lunar center of inertia.Then designing a high-performance joint-parallel numerical integrator for orbit prediction rapidly.Furthermore,the magnitudes of differently perturbed factors at different orbital altitudes and the influence on the accuracy of orbital extrapolation have been analyzed.It should be noted that this dynamic equation is universally applicable and can be extended to high-precision orbit prediction and orbit determination on Earth satellites or Mars probes.Secondly,a method of autonomous navigation using the inter-satellite position vector in inertial space is studied,and establishing its observation model.For the twobody dynamics only considering the gravity of the central celestial body,the theory of observability for the linear system and the nonlinear system are respectively used to analyze the observability of the proposed navigation system;then the local observability of the autonomous navigation system is intuitively described from the perspective of orbital geometry.Finally,the nonlinear filtering algorithms for autonomous navigation are studied.The basic program of autonomous orbit determination based on UKF are designed,and deriving the high-precision numerical solution of the state transition matrix of the system.For the two satellites' system which is operating on the lunar elliptical orbit,the numerical simulation of small initial errors and large initial error under the coplanar and noncoplanar orbital plane.Moreover,the factors that may affect the accuracy of orbit determination are analyzed and discussed.The results show that the autonomous navigation system can not only be applied to the orbit determination of lunar satellite,but also have certain robustness to the initial error and can meet the basic orbit determination requirements.