| This paper mainly studies the ocean current estimation method and the application of ocean current estimation in compass alignment.The damping network was designed based on the compass alignment loop,and then the ocean current velocity model was established.The ocean current estimation method based on SINS /GNSS combination and DVL was proposed.The system can effectively improve the compass alignment accuracy after the ocean current compensation.The thesis mainly includes the following aspects:1.Based on the in-depth analysis of the compass alignment loop,the horizontal damping network and azimuth damping network are designed strictly in accordance with the design principle of damping network,and the damping network is discretized into the inertial navigation system program by using bilinear transformation method.The damping effect of the damping network on the shula oscillation error and the geoperiodic oscillation error is verified by simulation.2.In view of DVL’s velocity measurement principle and working environment,the velocity measurement error form of DVL is studied,the ocean current velocity is modeled,and the ocean current estimation method based on SINS /GNSS combination and DVL is proposed.Then the strapdown,uniaxial and biaxial modulated INERTIAL navigation system and GPS data with different precision are used to estimate the ocean current velocity,and the estimation accuracy is compared.3.The transfer function of external velocity error and misalignment Angle error is derived,and the influence of different external velocity errors on external damping system is analyzed from time domain and frequency domain.Then,the influence of external damping system with and without ocean current velocity compensation is compared by simulation experiment.The mechanism of overshoot error in external damped system is analyzed,and the suppression method of state switch overshoot error is studied.Finally,the validity of the proposed algorithm is verified by sea data experiment. |
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