Modeling And Implementation Of Airborne Integrated Navigation System

As modern fighters carry out more and more heavy tasks and the battlefield environment becomes more complex and changeable,how to successfully complete the mission and return safely in a harsh combat environment is the goal of establishing an airborne integrated navigation system.The construction of an airborne integrated navigation system can be divided into three links:navigation and positioning,route planning,and flight control.That is to say,according to the current navigation and positioning of our aircraft and the external environment information,we plan the route of the aircraft,and finally use the obtained route information for flight control.This thesis focuses on the corresponding research on navigation and positioning and route planning,mainly includes theoretical design,model building and simulation verification.The specific implementation process is as follows:Firstly we introduce a trajectory simulation algorithm,which is used to design the flight trajectory of the fighter,obtain the fighter’s attitude,speed and position information,briefly describe the navigation principles of inertial navigation,GNSS,Tacom,beacons,Doppler,barometric altimeter,and radio altimeter.We establish the error model of inertial navigation,and inversely calculate it based on the navigation principle and flight trajectory to realize the environment simulation and sensor data generation of the airborne integrated navigation system.In this thesis,aiming at the problems of too much calculation in the process of multi-source information fusion of integrated navigation system,and different frequency of data update and the type of data output of different navigation method,we study the Kalman filter state fusion filter algorithm and Kalman filter observation fusion filter algorithm and establish the corresponding Information fusion model.For the Kalman filtering state fusion filtering algorithm,three weighted fusion criteria are used to achieve a balanced choice between the calculation amount of the multi-source information fusion process and the navigation accuracy;for the Kalman filtering observation fusion filtering algorithm,we change the original fusion method,which reduce the calculation amount without losing the calculation accuracy,but the reliability of the algorithm is not high and the fault detection is difficult.This thesis adopts different solutions to the problems of offline planning and online planning in the real-time route planning process.About offline planning problems,A*algorithm is used for global planning;about online planning problems,artificial potential energy method is used for local planning,which not only avoids the problem of too long search time of A*algorithm,but also avoids the problem that artificial potential energy method is easy to fall into local optimization.Aiming at the problem of excessive search space of traditional A*algorithm and impossibility of threat area,the node expansion direction,grid map marking information and segmentation method,evaluation function,and search direction are improved respectively.By changing the non-1 or 0 marking method of the raster map and adding threat factors to the evaluation function,the fighter can evaluate the threat level during the route planning process,and reasonably pass through some areas with lower threat levels,thereby shortening the flight distance.Aiming at the problem that the artificial potential energy method is easy to fall into local optimization,comprehensively considering the influence of the dynamic threat speed and distance factors,the speed and distance factors are added to the original repulsion function,and the dynamic threat is evaluated to set the repulsion factors in the.repulsion function.The simulation show that the algorithm has strong robustness to mobile threats in a dynamic environment and does not depend on a specific environment map.Aiming at the problem that the planned route may not meet the flight requirements,an optimization algorithm for cropping and smoothing the original waypoints is proposed,and the optimized waypoints can meet the flight requirements.