The Fault-Tolerant Navigation Technology For Target Drone Of UAV At Low Level Above The Sea Based On INS/GNSS/RA

Sea-skimming flight is used by anti-ship cruise missile as one of the important penetration pattern. Aiming at testing the performance of air-defence weapon and equipment, the target drone of UAV which is used to simulate the anti-ship missile should have the corresponding ability, such as the cruising flight at low level height keeping for long range. In order to improve the precision and reliability of navigation system, the fault-tolerant navigation technology for target drone of UAV at low level above the sea based on INS/GNSS/RA is studied in this paper.The key technology of cruising flight and its navigation demand at low level above the sea is analyzed first so as to realize fault-tolerant function, and then the positioning characteristics of strapdown inertial navigation system(SINS) and global navigation satellite system(GNSS) is researched. The practical GPS positioning accuracy of UAV cruising flight at low level above the sea is analyzed and evaluated. In view of the GPS and BDS positioning performance difference, the causes of the differences is analyzed from their respective constellation construction aspects. The integrated navigation system model of SINS/GPS is built and the simulation verification is completed.Then, the radar altimeter(RA) applied in measurement of UAV cruising flight at low level above the sea is researched. As the necessary sensor to realize low level flying, its working principle and measuring characteristics is analyzed. The mathematical models of irregular long crested wave and irregular short crested wave are established, through the calculation of wave height sub-UAV point and fixed sea region, providing a foundation of RA measurement error modeling and simulation in UAV dynamical flight. Considering the problem of real-time performance and visual effect, Through the suspend experiment above the sea and dynamical flight data, the performance of a RA is evaluated and analyzed. The modle of SINS aided height measurement on the condition of UAV maneuvering flight is built,the error compensation formula is deduced and it has good effect.Next, the fault-tolerant navigation technology applied to the target drone of UAV is researched. A plan of variable structure of SINS/GNSS/RA based on federated filter is designed in this paper. The residual adaptive estimation method is adopted to solve the high noise near the surface of the sea and prior statistics information do not tally with the actual. A new soft fault method of detection through analying the fault function quantitatively based on sliding window is presented and the information distribution coefficient is determined. The multi-sensor fault-tolerant mathmatical model of navigation system is built and with the fault injection, the simulation results indicate that the navigation performance meet the demand.Finally, a multi-sensor fault-tolerant navigation simulation platform is designed and realized. The platform with modular design can be used to simulate and test the technology of data fusion, fault detection and system reconstruction. It is runs compatible with dynamical flight data and provide an effective method of flight analysis and reappear afterwards. The instance simulation results shows that system functions is accord with the design demands. It has important reference value in the application of target drone of UAV flying at low level above the sea.