Modeling Of Air Data System And It's Application In Integrated Navigation

Air data system(ADS)has been widely equipped on aircraft,and its output of air data directly affects the safety and performance of aircraft.In order to ensure the accurate acquisition of air data and navigation information for aircraft in special scenarios where ADS fails due to faults.In this paper,the digital modeling of ADS and its application in integrated navigation are taken as a research topic.The digital modeling of ADS,the forward and backward calculation of air data parameters and the information fusion technology of ADS aided inertial navigation system are mainly studied.The main research work is as follows:?The basic working principle of ADS and the application characteristics of measuring sensors are researched,focusing on the calculation principle and error characteristics of air data parameters,such as pressure height,angle of attack and true velocity.On this basis,the mathematical model of ADS is established.The relationship between the excitation parameters and the output parameters of ADS presents a complex nonlinear function,which is not conducive to fast calculation.According to the characteristics of the pressure altitude equation,an improved solution is proposed based on Newton downhill method.A specific numerical solution is studied for the definition of lifting velocity.? Due to the fact that the model of ADS is not completely reversible,the estimation algorithms of true velocity,angle of attack and sideslip angle based on wind field and flight dynamics are studied respectively.On the one hand,according to the velocity vector triangle principle and considering that the wind speed is the basis of the solution of the true airspeed,angle of attack and sideslip angle.the effective estimation of the wind speed is realized by using atmospheric pressure as the observation quantity and using extended kalman filter(EKF).And then the true airspeed,Angle of attack and sideslip Angle are estimated.On the other hand,the differential equation forms of true velocity,angle of attack and sideslip angle in the motion law of aircraft are deduced.A cascaded double filter architecture is established.Considering the time correlation problem of observation caused by cascade filter structure,which is easily neglected in traditional cases,the above air parameters are effectively estimated by using unscented Kalman filter(UKF).? The integrated navigation algorithm of Strapdown Inertial Navigation System(SINS)based on air data assistance is studied.Aiming at the problem of instability of altitude channel in INS,the shortcomings of height channel of INS damped by atmospheric pressure height in traditional way are discussed.Considering that ADS can output redundant velocity information,such as true velocity,lifting speed,the true velocity in the airflow coordinate system is deduced as navigation observation.Based on Kalman filtering theory,SINS/ADS integrated navigation filtering algorithm based on true velocity/height information is designed and implemented.And the availability of the method is verified by simulation.Finally,aiming at the problems of traditional navigation information evaluation technology,a multi-source information fusion algorithm based on centralized Kalman filter and R-T-S fixed interval smoothing is designed,which provides a high-precision reference for the performance evaluation of navigation system.A navigation performance evaluation platform based on multi-source information fusion is designed and implemented,which provides a reliable operation environment and supports the research work of the thesis.