Research Of The Transfer Alignment Base On Ship Strap-down Navigation System

Transfer alignment is a dynamic alignment, which uses high precision Master Inertial Navigation System (MINS) to calibration the non-alignment Slave Inertial Navigation System (SINS). In modern warfare, weapon systems require rapid response capability and precision strike capability. Therefore, fast and accurate transfer alignment of inertial navigation systems on the weapon system which has become a key technology of the weapon equipments. This paper bases on the characteristics of ship environment to progress research on marine inertial navigation transfer alignment.First of all, according to basic principles of inertial navigation system, this paper gave the INS basic equations and the differential equations of strap-down matrix. Analyzing the main error sources of INS and establishing the error model of the inertial measurement unit, then inferred the speed error equation and attitude error equation. Taking the small misalignment angle and small installation error angle as research object, and inferred the velocity matching, the attitude matching and the velocity plus attitude transfer alignment matching method error model, and established the kalman filter model. According to the motion characteristics of marine, choose the common mode motion of the marine as the simulation condition, the paper in view of the velocity matching, the attitude matching and the velocity plus attitude matching to carry on the simulation analysis. The simulation result showed that the velocity matching transfer alignment is best when marine in the mooring state; when marine in the swing state the attitude matching and the velocity plus attitude matching can estimates of the installation error angle rapidly and accurately; when marine in the motion state the effect of the velocity matching and the velocity plus attitude matching are much better, but not much affected for the attitude matching.Secondly, this paper studied the factors which affect the transfer alignment accuracy, and focused on the lever arm effect errors and errors of inertial measurement devices. Analyzed the cause of ever arm effect errors, established the model of lever arm effect errors. Considered the lever arm errors based on the velocity matching transfer Alignment, established the state equation and estimated the length of the lever arm by the Kalman filter. Then use the length of the lever arm to compensate the lever arm effect errors which improve alignment accuracy. Next this paper studied the measurement errors of the inertial measurement unit in transfer alignment. The simulation result showed that the gyroscope and accelerometer of SINS both can affect the accuracy of the transfer alignment. Particularly gyroscope affects the accuracy of alignment more than the accelerometer. In practice it should compensate the errors of the inertial measurement unit of the SINS to improve the alignment accuracy.Finally, using the laboratory self-study FOG strapdown system to design and implement the experiments on the sea. Experiments were carried out under the mooring state and the motion state, using the attitude matching and the velocity plus attitude matching transfer alignment to analyze the experiment data. The experiment result showed that the motion state of marine impact on the results of transfer alignment directly. The effect of transfer alignment in the motion state is better than the transfer alignment in the mooring state, the result of velocity plus attitude matching transfer alignment is faster and more accurate than the attitude matching transfer alignment.