Study On Integrated Navigation Of GNSS/PseudoLite

Global navigation satellite system(GNSS)provide the most accurate space-time reference service of all-weather and open space environment.GNSS has been widely used in many fields such as national defense,military,communications,transportation,logistics and other industries,which profoundly changed people's life.However,the user receiver can not work normally due to the satellite navigation signal shelted by the environment.The GNSS system can not achieve the seamless navigation services for the integration of indoor and outdoor precise navigation of the last mile.The usability is one of the main problems of the GNSS system.As an enhancement and complement to the GNSS system,the pseudo satellite can improve the availability of the GNSS system in the shielding environment.This paper focuses on the three aspects of "optimal layout,optimal selection and integrity monitoring" for the integrated navigation technology of GNSS and pseudolite.The main innovations of this paper are as follows:(1)In the light of the multi constrained combinatorial optimization problem of pseudo satellite constellation layout,this paper proposed a new method based on adaptive genetic algorithm to optimize the layout of pseudo satellite constellation.In considering the angle between pseudolite and receiver,pseudo code isolation and near-far interference constraints,this algorithm locate minimum GDOP and the highest system availability to improve the accuracy and availability of the positioning system.(2)In view of the fast satellite selection problem in a variety of application scenarios,this paper proposed an improved adaptive genetic algorithm(MAGASS).The algorithm makes full use of the genetic algorithm of parallel processing and global optimization ability,compared with the existing algorithm,it can quickly find the optimal(or quasi optimal)satellite set,and meet the application requirements of GNSS multi-constellation satellite selection or receiver autonomous integrity monitoring algorithm in selection of more than 4 satellites.(3)A receiver autonomous integrity monitoring(RAIM)method is proposed which based on sequential processing extended Kalman filter(SPEKF).This algorithm uses the orthogonal decomposition method to convert vector computation into scalar computation which avoiding the matrix inversion in the iteration process.Compared to the existing RAIM methods with use of the Snapshot algorithm,the new approach is a kind of high precision and high performance RAIM algorithm under the full use of the observations of the current and previous epoch.In summary,this paper has achieved a better constellation layout optimization,intelligent satellite selection,and efficient receiver integrity monitoring algorithm which provides a certain technical basis for GNSS/PL integrated navigation system development and application.