Research On Rotary Inertial Navigation And Gravity Measurement Technology

Rotating modulation technology is a method of suppressing the error of inertial devices.On the basis of the existing inertial device processing process and calibration accuracy,the rotation modulation technique can improve the accuracy of strapdown inertial navigation and the accuracy of gravity measurement.Inertial navigation positioning accuracy is the guarantee of long-term maritime navigation,and gravity measurement is the main technical premise of major national strategic needs such as surveying and mapping and resource exploration.This paper mainly introduces the technical means to improve the accuracy of strapdown inertial navigation and gravity measurement through single axis rotation modulation.The research content mainly includes:(1)Through theoretical deduction and mathematical modeling,the specific principle of uniaxial rotation modulation to improve the positioning accuracy of inertial navigation and the accuracy of gravity measurement by adjusting the error of inertial devices is introduced.(2)This paper improves the existing 4-position 4-order uniaxial rotation modulation scheme.Comparing to the disadvantage and insufficiency of the existing scheme that the errors caused by the asymmetric rotation track and gyro drift during the whole period are not completely cancelled,this paper deduces the formula,designs a 16-order 4-position rotation scheme,and verifies the feasibility of the new scheme by simulation and turntable experiment.(3)Aiming at the problem that the zero bias of inertial devices affects the measurement accuracy of gravity vector in pure strapdown mode,the gravity vector measurement method based on single axis rotation modulation is studied.Uni-axis rotation modulation can make harmful signals high frequency.Low-pass filter can be used to filter high frequency harmful signals during gravity calculation.Through theoretical derivation and modeling and simulation,the attitude angle errors of pure strapdown mode,unidirectional continuous rotation modulation and reciprocating continuous rotation modulation are compared.It is proved that under ideal conditions,single axis rotation modulation can improve the horizontal attitude accuracy by modulating the zero offset of the inertial device,and compared with unidirectional continuous rotation,reciprocating continuous rotation can reduce the additional horizontal attitude error caused by gyro scale factor error.It can be known that the attitude accuracy of reciprocating continuous rotation modulation is the highest.The accuracy of gravity vector measurement under the three modes is compared.It is proved that under ideal conditions,single axis rotation modulation can improve the accuracy of gravity vector measurement,and the measurement accuracy of gravity vector measurement scheme based on reciprocating continuous rotation modulation is the highest.(4)Based on the above theory and simulation conclusion,aiming at the shortcomings of reciprocating continuous rotation in practical application and the poor performance of 16-order 4-position rotation scheme in filtering harmful signals,a double position rotation stop scheme is designed based on the reciprocating continuous rotation scheme.The gravity vector measurement experiments in pure strapdown mode,unidirectional continuous rotation and dual position rotation stop mode are carried out through the gravimeter.The comparison and verification of the three schemes show that the dual position rotation stop scheme can improve the gravity vector measurement accuracy and suppress the additional error excited by the gyro scale factor error under the condition of unidirectional continuous rotation.The turntable experiment shows the feasibility of the two position turn stop scheme.