Study on the application of NPF algorithm in the X-ray pulsar navigation

In this paper, a Nonlinear Predictive Filter (NPF) based on the minimum model error criterion is proposed to estimate the orbit information of spacecrafts in real time, which can solve problem contained in the X-ray pulsar navigation, such as strong nonlinearity of spacecraft system model and high-order model uncertainty. Firstly, A navigation orbit index function is established based on the models with uncertainty, and the model error is calculated which minimizes the index function, thus the influence caused by model uncertainty can be reduced and eventually the accuracy of autonomous orbit determination (OD) for spacecrafts can be further improved. The orbits of Path Finder, Venus Express and Beidou-01B are adopted to validate the navigation method. The simulation results demonstrate that the proposed method based on NPF has higher precision than EKF, and it can meet the requirements of autonomous OD accuracy for different orbit types of spacecrafts.