Research On High Precision Approach-and-landing Integratednavigation Based On GBAS

This dissertation is mainly focused on the research of high precision approach-and-landing integrated navigation based on ground based augmentation system(GBAS) for reusable launch vehicle(RLV). The traditional inertial navigation system(INS) is autonomous and fast in data update, which makes it possible for reliable and continual navigation. But its long-term positioning accuracy is low. In contrast, GBAS can still provide accurate positioning information over the long term, but its data update cycle is long and navigation continuity is difficult to guarantee in the complex weather conditions. Therefore, in order to enhance RLV’s navigation reliability, continuity and high precision in the approach-and-landing stage, a GBAS/SINS integrated navigation system is designed. The primary contents are as follow:First, the inertial navigation model of RLV is established and analyzed. Then, the SINS solver model and nonlinear error propagation model are derived according to the North-Air-East navigation coordinate. Numerical simulation based on gyroscopes and accelerometers is carried out to verify the correctness of the model.Second, the research is focused on GBAS, including its configuration, error sources and corresponding correction algorithms and solver methods. GBAS consists of three parts, namely space navigation satellites, terrestrial systems and users. Terrestrial receiver error, ionosphere delay and troposphere delay are the main positioning error sources. Based on the improved Hopfiled model, this paper analyzes and then gives the calculations of the troposphere refraction index, mean height of atmosphere and uncertainty of refraction parameters according to the statistical analysis for meteorological data of base station. Meanwhile, the pseudo differential algorithm is introduced to parameter of tropospheric delay. The GDOP satellite selection algorithm and GBAS solver are presented to achieve high-precision of users’ location. This method obviously improves the navigation precision at landing approach stage. Besides, by comparison with traditional satellite navigation(GPS), differential satellite navigation(DGPS), the positioning accuracy and effectiveness of GBAS are verified by simulation tests.Finally, SINS/GBAS integrated navigation systems and related numerical simulation analysis are given. By utilized the extended Kalman filter algorithm as the core filter algorithm, INS model as the nonlinear error propagation model and GBAS output as the exact location, SINS/GBAS is studied and the complex correction structure of Output&Feedback integrated navigation is proposed. Moreover, a SINS/GBAS simulation platform is built up in the Matlab/Simulink environment. The feasibility, effectiveness and positioning precision of the designed system are verified.