A Fast Transfer Alignment For Underwater Vehicles Based On Initial Azimuth Information

SINS initial alignment of inertial navigation system is one of the key technologies of underwater vehicles,rapid and precise is the important performance index,it directly affects the performance of autonomous navigation of underwater vehicles.For the multi underwater vehicles continuous rapid laying demand,this paper put forward a fast transfer alignment for underwater vehicles based on initial azimuth information,the azimuth angle error is better than 0.1o in 120 s,The error of pure inertial navigation is less than 1 nm in 1 hour.First a Moving Base INS provides accurate azimuth information and inaccurate horizontal information at the beginning of the initial alignment,then the alignment of navigation in the inertial system is carried out by Kalman filter using initial horizontal angles error and velocity error as system states and different auxiliary information measurements as observables.The main research work of this paper is as follows:(1)Research and analysis underwater vehicles alignment algorithm that has proposed,mainly for under the condition of different auxiliary submersible self alignment algorithm and velocity/attitude matching transfer alignment algorithm.The self alignment algorithm includes backtracking and non backtracking situation.Experiments show that the existing algorithms need long time to finish alignment with low precision,when the gyro accuracy is low the azimuth accuracy is low and still can not be fast convergence under the initial azimuth information.so it is difficult to meet the requirements of the actual background.(2)According to the actual demand and considering the speediness,accuracy,applicable to different precision characteristics of inertial measurement unit,this paper proposes a fast transfer alignment for underwater vehicles based on initial azimuth information.With different auxiliary information,the paper derivate underwater rapid transfer alignment filter model and the corresponding navigation solution process including attitude updating,velocity updating and position updating.(3)Different experiments are carried out for the design of the algorithm.Mainly including initial horizontal error margin analysis experiment,considerable measure and fast convergence experiment and simulation analysis of the algorithm for different precision components.The analysis shows that the algorithm can achieve the design goal of the algorithm.(4)The underwater measured data respectively in the Doppler velocity aided,GNSS velocity aided,GNSS location aided,GNSS velocity and position of auxiliary conditions with the traveling back alignment algorithm comparison algorithm alignment accuracy and rapidity.The experimental verification algorithm can accomplish the alignment task under different conditions of motion.