SINS Alignment Method In Inertial Frame With Swinging Base

Strapdown Inertial Navigation System (SINS) is of continuous development that will gradually replace the Gimbaled Inertial Navigation System (GINS) as the main navigation system in many fields. As one of key technologies in SINS, initial alignment has been widely researched. This dissertation focuses on SINS self-alignment methods under the condition of swinging base.Firstly, the basic principles of SINS and the related theories of the initial alignment are described in detail providing theoretical basis for the following alignment process.Secondly, disadvantages about the classical alignment method based on analytical mechnisam are analyzed and the inertial frame as intermediate transition frame is introduced to solve these. Furtherly, a self-alignment method for SINS with three gravitational apparent motion vectors is proposed for the case without latitutde information. The feasibility of the proposed method is verified by simulation.Thirdly, since the alignment accuracy of three vectors method is easily suffered from the random noise of accelerometer, three improved methods-the filtering method based on the online adjustment of Kalman's filtering parameters, the wavelet denoising method and the weighted recursive least square(WRLS) method-are proposed respectively. The feasibility of the improved methods above is verified by simulation and the alignment accuracy of different methods is compared.