Research On Fastness Of The Initial Alignment Technology Of Marine SINS

Initial alignment is the key technology of strapdown inertial navigation system,which directly affects the navigation performance of strapdown inertial navigation system.Alignment time and alignment accuracy are two important indexes to measure the initial alignment performance.In order to further shorten the alignment time and improve the initial alignment performance,this paper focuses on the coarse alignment,fine alignment and transfer alignment under large misalignment angle of strapdown inertial navigation system:(1)In the initial alignment of strapdown inertial navigation,because the convergence speed of the horizontal attitude of the carrier is obviously faster than that of the carrier heading,in order to achieve the fast coarse alignment of the swing base,only the convergence speed of the carrier heading needs to be improved.Aiming at this phenomenon,the horizontal attitude is obtained by the multi vector coarse alignment method,and then the carrier heading angle is estimated by the particle swarm algorithm.The effectiveness of the proposed method is verified by the turntable test.The coarse alignment method of particle swarm optimization can converge within 200 s,and the steady-state accuracy is within 0.1 degree,while the multi vector coarse alignment algorithm needs more than 300 s to achieve the same accuracy.The experimental results show that the initial alignment method based on PSO algorithm can not only ensure the attitude accuracy,but also significantly shorten the coarse alignment time of SINS.(2)In order to get higher alignment accuracy,traditional SINS often need longer alignment time.In this chapter,a fast alignment algorithm based on data storage and cycle solution is proposed for the condition of swing base.Based on the fast computing ability of modern computer,firstly,the attitude matrix is decomposed into the product of initial time attitude matrix and two time-varying matrices by using the chain multiplication rule of matrix,then the initial time attitude matrix is obtained by using the inverse solution of two time-varying matrices and Kalman filtering fine alignment results,and Kalman filtering fine alignment is continued by using the data of inertial devices stored in computer The final result of Kalman filter fine alignment is obtained by ring solution.The simulation results show that the fine alignment algorithm based on forward iteration can achieve the precision of traditional SINS with only 120 seconds of data,and it is significantly higher than that of traditional SINS with120 seconds.The fine alignment algorithm based on forward iteration proposed in this paper can greatly shorten the fine alignment time.(3)In view of the limited CPU storage and calculation capacity of shipborne weapon under the condition of large misalignment angle,and the complexity and large calculation of nonlinear transfer alignment model,two transfer alignment algorithms based on linear filtering model under the condition of large misalignment angle are proposed.One is the transfer alignment algorithm of coarse pair and fine pair under the condition of large misalignment angle.First,the coarse alignment model of the transfer alignment is derived,and the large misalignment angle is converted into the small misalignment angle,then the alignment model of velocity +angular velocity matching is used for fine alignment.The other is the algorithm of converting the traditional nonlinear model into the linear model by using quaternion,in order to be more sensitive to the ship's swing transportation The angular velocity of master and slave INS is added to the observation.Finally,the validity of the two transfer alignment algorithms is verified.