Research On UAV Navigation System Based On MEMS/GPS Integrated Navigation

The integrated navigation of MEMS inertial sensors and GPS is widely applied in real-time navigation, especially for the navigation system of unmanned aerial vehicle(UAV),for which is more suitable comparing to other approaches due to its features of small size,flexibility and light weight. However most traditional navigation systems are unable to fully meet the demand of UAV navigation system,real-time performance,reliability and accuracy.This thesis focused on optimizing the integrated navigation system according to the UAV navigation system features mentioned above and combing MEMS-IMU with GPS information thus to best fulfill the requirements of navigation system.The navigation system of tight integration of GPS time differenced carrier phase (TDCP)and inertial navigation data is mainly used in the thesis, in which high-precision carrier phase information is applied and the complex process of solving ambiguity is avoided, therefore the real-time system is improved, and inertial error is effectively inhibited for outputting precise navigation information after combined with inertial navigation system with good real-time performance, stable error and low precision and error divergence. However the approach of TDCP positioning doesn't cover absolute positioning and is unable to suppress the slow-cumulative effect of INS position error information. Consequently, the pseudo-range auxiliary is introduced here to provide position damping for the system in a longer cycle and to form a pseudo-range/TDCP/INS integrated navigation system, which eliminated shortcomings, combined advantages, and effectively improve the performances of the integrated navigation system.Additionally, the other GPS navigation data is discussed. The GPS outputs high-precision speed information and single-antenna attitude-measurement information, based on which the loose integration is developed and then compared with the tight integration of TDCP.As for the tight integration, the mathematical model for the integrated navigation system is built, the block diagram is designed, error model of micro inertial sensors is analyzed, state and measurement equations are established, extended Kalman Filter especially for the system is designed, and finally the rationality of the system is tested by simulation. Besides, as regards the loose integration simulation, the difference between the two, pros and cons of each, and suitable environment are analyzed. The result of the test has shown that the integrated navigation system designed in this thesis is suitable for UAV,and meets the system requirements of real-time performance, accuracy and reliability. Under the circumstances where the SINS error estimation performance can be guaranteed by the loose integration,the loose integration can be primarily used; when the environment no longer meets the requirements of loose integration and the loose integration performance is descended, it can be switched to the tight integration mode so as to ensure that the system requirements of real-time performance, accuracy and reliability are achieved.