Research On Initial Alignment Technology Of Strapdown Inertial Navigation Assisted By Multiple Information

Modern warfare requires higher and higher precision for the weapon system's strike.Ammunition dexterity technologies such as ballistic correction and terminal sensitivity have gradually become research hotspots.Strapdown inertial navigation has the advantages of small size,easy integration,and strong anti-interference ability,and is widely used in the improvement of ammunition dexterity.However,when the smart ammunition is launched,it will be affected by the environment of high speed,high overload,etc.,and the initial alignment of the ground static base that cannot be inertially guided.In response to this problem,this paper studies the initial alignment method of strapdown inertial navigation that combines geomagnetic survey information,ballistic information and satellite information.The main research contents are as follows:Taking the two-dimensional trajectory correction projectile as an object,firstly,the relevant mathematical model is established,and the navigation information solution algorithm and the system's attitude,velocity and position error equations are studied.Then,the strapdown inertial navigation algorithm is simulated based on the simulation data of the inertial measurement element,which verifies the feasibility of the algorithm.Under the condition of a static base,the coarse alignment method is first studied,and then,by analyzing the error of the inertial element,the accelerometer offset and the gyro drift are added to the system state quantity,and the Kalman filter fine alignment alignment is designed Method,and its simulation analysis.The simulation results show that in the initial alignment under static base conditions,the convergence rate of the horizontal misalignment angle is faster,while the convergence rate of the azimuth misalignment angle is slower.Through the semi-physical simulation of the geomagnetic attitude measurement method,the availability of geomagnetic roll angle information is verified;then the external ballistic parameters are simulated to obtain the pitch angle and yaw angle of the projectile;finally,the above auxiliary information is calculated with strapdown inertial navigation The resulting difference is input to the Kalman filter as an observation to complete the initial alignment of information fusion.Simulation results show that,compared with self-alignment,the alignment method of information fusion has improved alignment accuracy and speed.During the flight of the projectile,as time accumulates,the strapdown inertial navigation solution will generate cumulative errors,which require dynamic alignment after satellite positioning.The traditional dynamic alignment method uses a speed/position matching alignment method.This method has a slow alignment speed and poor observability of the azimuth gyro,resulting in reduced alignment accuracy.In this paper,the satellite's speed information is used to calculate the pitch and yaw angle of the projectile,and the geomagnetic information is used to provide the roll angle.Based on the traditional speed/position matching method,the three attitude angle information is added to the observation measurement to improve the system.The observability makes the dynamic alignment faster and more accurate.