A Fast Initial Alignment Filtering Method of Velocity and Attitude Matching on Dynamic Base for Underwater Vehicle

The alignment of underwater vehicle on dynamic base is studied, and an error model of strapdown inertial navigation system(SINS) is established. The underwater vehicle runs straightly and acceleratively in waves and winds during the process of alignment. Meanwhile the information of velocity and attitude from global positioning system(GPS) is used to help implement alignment, so the observation equations can be obtained. An alignment method based on quaternion attitude updating with the matching of velocity and attitude is proposed to estimate three initial misalignment angles. Consequently the misalignment angles are accurately and quickly estimated. Especially the method reduces the time for estimating azimuth error, and improves the accuracy of estimation. The simulation results illustrate the efficiency of the method.