A real-time airborne terrain aided inertial navigation system and its performance analysis

The current terrain aided navigation system has a shortcoming that it depends on terrain feature, so we need to select the terrain matching area and plan the flight path according to the flight mission in advance. In this paper, we present a real-time airborne terrain aided inertial navigation system. The system can plan and select the matching area online according to the heading angle and estimated position errors during aircraft flight, and adopt the appropriate terrain-aided navigation algorithm for different terrain areas and flight conditions. So it can ensure the positioning accuracy and improve the ability of carrier to maneuver at the same time. In order to verify the performance of the system, a flight simulation experiment and a real flight test are carried out, and we conduct a research on the performance of matching area planning and real-time positioning. The tests results show that the system can improve the ability of carrier to maneuver and the performance of real-time positioning. In addition, the system has a higher positioning accuracy and reliability than traditional TERCOM and SITAN methods. The position error is less than 50 m in acquisition mode and less than 18 m in tracking mode with the terrain elevation map of 25 m-resolution.