Research On Initial Alignment Technology Of SINS In Inertial Space

Aiming at the initial alignment problem of strapdown inertial navigation system with the interference of external factors or carrier under the condition of movement, initial alignment based on inertial space has become the most popular method at nearly ten years.Based on initial alignment in inertial space,the analysis of initial alignment accuracy is completed and the rapid fine alignment method is put forward. The contents include the following aspects:Firstly,the basic theory of strapdown inertial navigation system is introduced,including:The definitions of coordinates used in the thesis;the basic principle of strapdown inertial navigation;Basic navigation algorithm of strapdown inertial navigation system and reverse navigation algoriyhm of strapdown inertial navigation system;The main error sources of strapdown inertial navigation system and the initial alignment error; Error model of strapdown inertial navigation system based on large azimuth misalignment,including the velocity error equations and the attitude error equations; Based on the SINS error model of large azimuth misalignment,the SINS error model of small misalignment can be obtained by approximating the small angle.The basic theory provides a theoretical basis for the following research.Then,the coarse alignment's error analysis of strapdown inertial navigation system based on inertial space is studied. Starting from the coarse alignment principle of strapdown inertial navigation system based on inertial space,the error factors of SINS initial alignment is analyzed under the condition of static base.Based on the coarse alignment principle and error factors of SINS initial alignment,four kinds vector selection modes(two of them has the orthogonal three axis and the other two has the non- orthogonal three axis )of initial alignment accuracy are analyzed under the condition of static base. Simulation is done to verify the above conclusion.Then,based on coarse alignment of strapdown inertial navigation system in inertial space,SINS rapid fine alignment of small misalignment in inertial space is studied. The basic navigation algorithm of strapdown inertial navigation system in inertial space and The reverse navigation algorithm of strapdown inertial navigation system in inertial space are introduced,Based on the basic navigation algorithm and the reverse navigation algorithm,rapid fine alignment principle is put forward.Based on the SINS error model of small misalignment in inertial space,the basic filtering model and reverse filtering model are built.At the same time,filtering steps are given in detail. Simulations are carried out under the condition of the staic base and the small angle sloshing. Experiments are done to verify the simulation results.Finally,in view of the external factors influence on the initial alignment resulting in the effect of coarse alignment unsatisfactory,SINS rapid fine alignment of large azimuth misalignment angle in inertial space is studied. Based on the SINS error model of large azimuth misalignment in inertial space,the basic filtering model and reverse filtering model are built.At the same time,the modeis are lineared. Simulation results show that reverse navigation can shorten the time of alignment.Experiments are done to verify the simulation results.