Research On Autonomous Navigation Method Of Interplanetary Flight

With the intensive research of space exploration, more spacecrafts have taken on the interplanetary flight missions. It is very important to determine the accurate orbit of spacecraft. At present, the navigation of interplanetary spacecraft mainly depends on the radio communication with ground station which has some disadvantages. So the ability of autonomous navigation is urgent necessity. Among several autonomous navigation methods, the celestial navigation method which is accurate and absolutely autonomous is appropriate for interplanetary spacecraft. This paper research the autonomous celestial navigation technology of interplanetary spacecraft on the transfer orbit. It is mainly described as follows:Orbit dynamical equations of autonomous celestial navigation system based on multi-body problem are established which include the perturbations of other celestial bodies'and solar radiation pressure perturbation. The measurement modes are researched and the measurement model is constructed based on the starlight angular distance.The nonlinear Kalman filter arithmetic is studied in the paper. Extended Kalman filter (EKF) and unscented Kalman filter (UKF) which are widely used are given. The square-root unscented Kalman filter (SR-UKF) which has better accuracy and numerical stability is used for estimating the position and velocity of spacecraft.An autonomous navigation scheme is given and observability is discussed. Two reduced methods are given to analyze the observability and observability index. A locating method with the geometric arithmetic is demonstrated.The availability of autonomous navigation scheme is proved by numerical simulation. The observability and navigation accuracy are deeply researched with simulation.