Research On Transfer Alignment And Integeater Navigation Method Of Airborne Guided Bomb Under Large Azimuth Misalignment Angle

Because of its simple structure,convenient use,long range,high hit accuracy,low cost,high efficiency-to-cost ratio and many other advantages,air-guided bombs are favored by the military of various countries.This paper focuses on the key technologies of INS/GPS tightly coupled integrated navigation and large azimuth misalignment angle initial alignment of missile navigation system.The purpose is to improve the initial attitude accuracy of strapdown inertial navigation system at large azimuth misalignment angle as far as possible under certain precision level of inertial components,so as to improve the overall performance of the navigation and positioning system.Strapdown Inertial Navigation System(SINS)has the advantages of simple structure,small volume,light weight,low cost,simple maintenance and high reliability.It is widely used in missiles.However,the precision of SINS is difficult to meet the requirements of navigation precision because of the accumulation of time.In this paper,the INS/GPS tightly coupled integrated navigation technology is studied by using the integrated navigation method with strapdown inertial navigation system as the main body of the satellite navigation system.The input of the integrated filter is the difference of pseudo range and pseudo range rate from the output of GPS receiver and the inverse calculation of the pseudo range and pseudo range rate from the ephemeris of inertial navigation and GPS receiver.The INS system error is estimated and corrected.The results show that the precision of average positioning and velocity measurement is greatly improved and the position and velocity curves are smoother than that of satellite navigation.The precision of SINS is affected by the error of inertial devices and the result of initial alignment.One of the main factors causing the error of SINS is the initial alignment error.In practical application,the error model of strapdown inertial navigation system may not conform to the hypothesis of small angle because of emergency hang-up and improper operation.In this paper,the nonlinear error equation of strapdown inertial navigation system is deduced,and the observation equation is constructed by using "velocity + attitude" matching mode,and the optimal estimation is made by using unscented Kalman filter.The influence of link arm and time delay on transfer alignment is compensated,and the installation error angles and gyroscope bias can be accurately estimated.