| The inertial devices have a certain device error after each power-up and long-term use.This part of the device error will cause great error to long voyage,high precision inertial navigation system when it is navigation and positioning.In order to improve the navigation precision and reduce the influence of device error on the system performance,it is necessary to calibrate the inertial measurement unit after each start-up and long-term use of the inertial navigation system.Successive start-up online calibration technology of dual axis rotating and periodic online calibration technology of dual axis rotating are carried out in combination with the actual requirements of developing high-precision inertial navigation system of FOG.Firstly,because of the gyroscope and accelerometer generate successive start-up errors when the inertial navigation system is started each time,this paper proposes a successive start-up online calibration technology of dual axis rotating based on Kalman filter.The constant deviation of the gyro and the accelerometer has a direct effect on the misalignment angle of the initial alignment.In the process of initial alignment,the biaxial rotation mechanism is used to rotate according to the designed indexing scheme.The constant deviation of the gyro and the accelerometer is excited,and then the gyro drift and the accelerometer bias are estimated and compensated.Then the alignment misalignment angle is reduced,and the alignment accuracy is improved.The key to the successive start-up online calibration technology is the design of biaxial indexing scheme.In this paper,the observability of the double-axis rotating SINS device under static and rotational conditions is analyzed by the global observability analysis method before the design of the indexing case,and the observability of the device error in the rotation of the biaxial rotating mechanism is determined.Then,through the observability analysis of the device error,the position arrangement path of the indexing scheme is designed.At last,the technique is implemented according to the designed eight position indexing scheme by starting the successive start-up online calibration algorithm.Subsequently,the parameters of the inertial measurement unit will be changed after a long time use of the inertial navigation system.The periodic online calibration technology of dual axis rotating for calibrating the error parameters of the inertial navigation system is presented in this paper.Similarly,the key to the periodic online calibration technology of dual axis rotating is the design of the biaxial indexing scheme.Therefore,the principle of device error calibration is briefly introduced,and the relationship between device error and indexing scheme is established.Then,three kinds of indexing schemes are designed according to the principle of calibration and the characteristics of biaxial rotation mechanism.(three groups of 3-position indexing scheme,10-position indexing scheme and 12-position indexing scheme).Based on three groups of 3-position indexing scheme,the error process of the device under static pedestal is deduced,and the expression of calibration error parameter is obtained.At last,by simplifying the inertia component error model,a periodic online calibration algorithm based on Kalman filtering is designed to compare the three schemes.Finally,the validity of the 8-position indexing scheme for device error estimation and SINS initial alignment accuracy is verified by the successive start-up online calibration simulation experiment.The validity of device error calibration is validated by Periodic online calibration simulation experiment,and the optimal 12-position indexing scheme is selected.Then,the validity of the 8-position scheme is verified by laboratory test and real ship test of the constructed dual-axis rotary SINS demonstration prototype.Indoor calibration experiment is carried out on a dual axis rotating SINS demonstration prototype based on the selected 12-position optimal indexing scheme.The effectiveness of the scheme is verified by the navigation test before and after calibration. |
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