Design Theory Of Inertial-based Intelligent Fault-tolerant Integrated Navigation Key Issues Study

It is a powerful way to increase the cost performance ratio by integrating several kinds of navigation systems. When the classical Centralized Kalman Filter (CKF) is used in this kind of integration, there will be two disadvantages: firstly, there exists real time computation difficulty. Secondly, the fault tolerance capability is poor. Once one of the subsystems breaks down, all the other subsystems are affected. However the Federated Kalman Filter can be used to design the integrated navigation system with high precision and good fault tolerance flexibly. Hence, the Federated Filtering theory is getting more and more attractive in navigation field. In the thesis, the theory and the algorithm of Federated Filtering are described, and the estimation optimality is demonstrated in detail. Aiming at a certain type of airplane equipped with many navigation equipments as SINS, GPS, DVS, ADS, MG, VG, an integrated navigation system with the fault tolerance property is designed. With the many problems to be considered and solved in engineering, the following work has been done via simulations: 1) The performance of the federated filter designed is compared with that of CKF; 2) The system level fault detection of the local filter (LF) is studied. The State x2 Test Method and the Residue Test Method are discussed, and the other two approaches of fault detection based on the former two methods are proposed: i.e. 2 the approach combined State x Test Method with the Residue Test Method, and Residue Test Method with Safe Term Observation. 3) A new method of LFs? system level fault detection is proposed. The value of the fault vector is estimated using adaptive filter, and then compared with the threshold established by measurement noise variance. If the permissible value is exceeded, the fault is detected. Directing toward the SINS/GPS system, the fault detection simulation is carried out with the approach, and a good result is achieved. 4) The component level fault detection of SINS that can assure the common reference system against abnormal conditions is investigated. Generalized Likelihood Ratio Test Method is introduced. Fault detection method and simulation results are presented when one gyroscope is in troubled.