Research On Key Technique Of Airborn SINS/CNS Integrated Navigation System

Celestial navigation is an independent, near autonomous navigation technology to determineone's geographic position and attitude by indentifying the observed celestial objects. Many powerfulmilitary nations put great efforts in the research on celestial navigation technology which is one of themost important navigation technologies in modern high-tech war for its independent characterbecause that the selected celestial objects for celestial observation can't be destroyed by humanactivities and they are not subject to geographical restricts. Based upon the characteristics of celestialnavigation, this dissertation elaborates the research on key techniques including the loose integratedSINS/CNS technique and tight integrated SINS/CNS technique with the airborne environment, andthe nonlinear filtering adapting to SINS/CNS integrated system. The research provides the theoreticalbasis to improve its performances for SINS/CNS integrated system.Considering the requirements for celestial position determination in airborne application, thispaper explores the basic theory of celestial position algorithm as the beginning and the celestialposition algorithm adaptive to airborne environment when the star tracker is strap assembled on aplane has been proposed. With the intention to remove the restrictions caused by horizontal coordinatein celestial position determination, the technique of establishing high precision horizontal attitudecoordinate was studied. The improved strap-down celestial navigation localization algorithm andproject based on virtual horizontal attitude coordinate correction was elaborated, which improved theprecision of celestial position determination effectively.To correct the inertial error effectively through the celestial navigation system and improve thecomprehensive performances of the integrated navigation system, this paper studies the SINS/CNSloose integrated navigation system which is based on the measurement of celestial position andattitude information.To insure the observability of altitude channel of inertial navigation system, thescheme of integrated SINS/CNS assisted by barometric altimeter is also proposed. Furthermore, thispaper discusses the additive quaternion model with the attitude error of inertial system based on thecelestial attitude information. And a new inertial/celestial attitude integrated scheme based on thecompensation of additive quaternion with attitude error is presented which lays the foundation forimproving the precision of integrated system.To further increase the performance of SINS/CNS integrated system, the algorithm of SINS/CNSintegrated navigation based on celestial angle observation is scrutinized on the basis of study on loose integrated mode. The tight integrated technology of SINS/CNS with the celestial angle measurementis studied on the analysis of the height angle and the azimuth angle information. And the tightintegrated mode based on position errors has been elaborated. Concerning the attitude errors in CNShorizontal attitude coordinate, the tight integrated SINS/CNS mode with the consideration of attitudeerrors has been presented in this dissertation.Considering that the celestial measurement would be inevitably affected by the inertialnavigation error which leads that the observation equations are nonlinear,the nonlinear characteristicof measurement for SINS/CNS is analyzed and the unscented Kalman filter(UKF) is adopted toestablish the INS/CNS nonlinear integrated system. The tight integrated project of airborne INS/CNSwith simplified UKF based on celestial angle observation difference has been presented which solvesthe problem of nonlinear observation in SINS/CNS integrated navigation system.Finally, to verify the performance of the SINS/CNS integrated navigation system proposed above,this paper designs a simulation platform for SINS/CNS integrated navigation system with detailedscheme.Focusing on the application of SINS/CNS integrated navigation system for flight, thisdissertation systematicly elaborated the research on both loose and tight integrated SINS/CNS.Theresearch on SINS/CNS integrated navigation system conducted by the author has importantsignificance on the engineering application.