Research On Fast Alignment Technology Of Optical Fiber Strapdown Inertial Navigation System

Initial alignment technology of strapdown inertial navigation system(SINS)is a key technology related to the normal operation of inertial navigation system.The rapidity and accuracy of alignment are the two vital indicators of the technology.In this paper,the following research is carried out for the fast problem of inertial navigation system:1.Firstly,the research background of the subject and the research status in this field at home and abroad are introduced.By analyzing the reasons affecting the alignment speed,three aspects of observability,data utilization and slow non-linear convergence are analyzed,which provide a complete guiding principle for the full text.2.In view of the low observability of the traditional analytical coarse alignment plus Kalman filter fine alignment method under stationary base,a fast fine alignment method based on augmented measurement is introduced.The model of incorporating the angular rate of gyro measurement into the measurement is deduced in detail.The reasons for accelerating the convergence of the new model are analyzed from two aspects of the observability and error propagation equations,respectively.Finally,it is verified by simulation and turntable test.3.A fast alignment method of strapdown compass based on forward iteration is proposed under the condition of swaying base.With the help of the idea of reverse navigation,the reverse process is omitted instead of the chain multiplication rule of matrix.When the data is stored in the first section,the change of the body frame relative to the initial time is stored at the same time.The applicable conditions of the new method are analyzed,and the simulation and turntable test verify that the proposed method has the same accuracy as the forward and backward solutions.4.In motion base,a fast alignment algorithm based on velocity which under body frame is proposed.Based on the idea of reverse navigation in Chapter 3,the second alignment is proposed on the basis of the first alignment,and the position navigation is also carried out in the second alignment to achieve real-time position in the alignment process.5.A fast transfer alignment model based on linear quaternion model is proposed to replace the traditional nonlinear model with large misalignment angle.A fast transferalignment model based on quaternion is deduced and verified by simulation,in order to achieve fast transfer alignment with quaternion model under large misalignment angle.