Research On Airborne Alignment Method Of Missile-borne SINS/GPS Integrated Navigation System

The modern military situation is becoming more and more complex.Precision guided weapons have become indispensable standard equipment for the development of modern armies all over the world.With the continuous improvement of satellite navigation system,and the inertial navigation system is free from external interference,SINS/GPS integrated guidance has become the mainstream guidance mode of modern guidance weapons.Because of the harsh environment such as high rotation and high overload,strapdown Inertial Navigation System(SINS)is ineffective in ground static base alignment before launching,so it is necessary to carry out air alignment.Based on the above research background,this topic is under the traction of the longitudinal project.aiming at the problem that the initial attitude angle,especially the roll angle,is difficult to obtain in the harsh environment such as high rotation,high overload and so on,this thesis designs an air alignment method of SINS/GPS integrated navigation system based on missile-borne environment,which has fast alignment speed and high accuracy,The self-alignment of roll angle in the air,the secondary alignment of course angle and pitch angle in the air are discussed in detail.Traditional roll angle self-alignment in the air uses geomagnetic sensors to measure roll angle,but this method is vulnerable to external interference and can not work under strong magnetic interference environment.When the missile axis is close to the magnetic vector,it will produce singular output,which leads to the disadvantage of attitude calculation.Considering the gravity projection output of the accelerometer in the cross section of the projectile which follows the change of roll angle in the high rotation state,the roll angle information can be obtained according to the gravity projection,while the low-pass filtering can retain the low-frequency signal and the direct current signal.The gravity projection can be obtained by subtracting the original output of the accelerometer from the low-pass filtering result,thus the roll angle information without cumulative error can be obtained.Although there is no cumulative error in the measurement of roll angle by accelerometer,because of its slow dynamic response,the measurement information of roll angle is inaccurate,and thedynamic response of gyroscope is fast,but there are cumulative errors.Therefore,a method of roll angle alignment based on Kalman filter is proposed,which combines two-axis accelerometer and single-axis gyroscope.On the basis of improving the dynamic response,the cumulative error caused by gyroscopeThe traditional aerial alignment method uses the velocity + position matching method.Because of the short flight time of the projectile,the method has a slow alignment speed,and the observability of the East and the sky gyroscopes is very low,which results in the low accuracy of attitude angle alignment.Considering the rapid flight speed of the projectile,GPS velocity information can provide high-precision heading and pitch information.Because of the low update frequency of GPS,it can not reflect the complete attitude information in high dynamic environment.Therefore,based on the traditional Kalman filter velocity + position matching method,this thesis proposes to use GPS velocity information to increase heading angle and pitch angle measurement information,increase attitude angle observability,speed up attitude angle alignment speed and improve attitude angle alignment accuracy.Finally,the ballistic simulation analysis and semi-physical simulation validation of the roll angle air self-alignment method and the accelerometer roll angle measurement method,gyroscope roll angle measurement method are carried out.The experimental results show that the roll angle air self-alignment method effectively improves the accuracy of roll angle.At the same time,the air secondary alignment method,traditional air alignment method,GPS measurement of heading angle and pitch angle are simulated and analyzed.It is verified that the air secondary alignment method has the characteristics of fast alignment speed and high alignment accuracy.Therefore,this study has important engineering application value.