Initial Alignment And Field Calibration Technology Of Strapdown Attitude And Heading Reference System Based On Fiber Optic Gyro

With the widely applications of strapdown attitude and heading reference system(SAHRS)based on fiber optic gyro(FOG)in military field,how to improve the tactical performance and maintainability of the current system are the key missions and urgent requirements that we are faced.This paper starts from the actual demands of SAHRS on FOG,conducting the related researches on field calibration technology and initial alignment technology.The mainly research work including the following four aspects:Firstly,this paper researches comprehensively alignment method on sea based on multi-vector attitude determination algorithms(AD).First of all,the uncertainty and precision analytical formula of the TRAID and QUEST algorithms are derived with details,which is started from the AD algorithm.It set up the unity relationship of these two algorithms and the relationship of the vector distribution matrix and the precision of attitude determination is analyzed.The precision superiority of the QUEST method is verified by the simulation.Meanwhile,the numerical relationship between inertial sensors' error and vector observation error are separately derived in Gravity and Gravity integration vector observation conditions with the inertial coordinate alignment model.The integral vector observation based vector optimization scheme is proposed by the derivation and analysis.Moreover,the alignment precision is compared and analyzed by different vector configuration schemes,and also the effectiveness and efficient of the optimal scheme is verified.In addition,taking the short time low-pass filter to observation vector as the tendency item extraction of Gravity vector and introducing the EMD tendency item extraction method,which are adopted to solve the swing base di sturbance problem.The external extending method with actual data is proposed to eliminate the endpoint effect of EMD.At last,the applicability of alignment and filter scheme is testified by both swing turntable experiment and shipborne experiment.Secondly,this dissertation elaborates and demonstrates systematic calibration theory based on error separation technique comprehensively and proposes an effective calibration scheme aided by low-precision turntable.At the beginning,the calibration observation equation and calibration process is derived and proposed based on velocity error observation and after calibration condition constraint and calibration model being built.After that,two kinds of error separation sub-scheme with same position and different position conditions after the turntable rotation are analyzed and verified.Moreover,the error analysis and improved optimization are conducted on these two sub-schemes.Finally,the comprehensive calibration scheme is designed with the optimal analysis,fiber system calibration experiment are utilized to verify the effectively of the proposed method.Thirdly,the muti-position static calibration method without turntable has been deeply researched.State group's observable orders with single postion is analysized after error equation decomposion,and the parameter estimation method based on extended observation has been proposed,simulation has verified the method can improve the alignment precision and speed.Aiming at muti-position shceme optimization problem,matrix's condition number is taken as state identification target function,and the optimization scheme based on optimized artificial fish swarm algorithm is proposed,simulation testified the superiority of optimization method and optimization index.Based on the proposed calibration scheme,muti-postion calibration experinment is proceeded with the manual turnover methods by hexahedron and platform,system precision is improved effectively after calibration.Fourthly,this research proposes a star sensors-aided shipborne calibration method,and provides integrated and decoupled calibration schemes.The star sensors-aided integrated calibration method is proposed and the 18 dimensional state equation and measurement equation are built up.The simulation result shows that this method can estimate the star sensors installation errors and gyroscope drift errors online.However,the estimation result of gyroscope drift is shown with low precision and also the method could not estimate the accelerometer errors.According to this problem,this paper proposes shipborne inertial coordinate based decoupled calibration method.It uses the inertial attitude information of the star sensors to construct attitude reference,and adopts the additive quaterion error as state variables to construct the 10 dimensional state equation and measurement equation,which can estimate the gyroscope drifts.What's more,the estimation of accelerometer error is based on the velocity error observation equation that is the combination of inertial coordinate system reference and a ccelerometer observation.And it could implement the decoupling of gyroscope and accelero meter error estimation.Consequently,the swing base simulation experiment demonstrated that this method could improve the accuracy and speed of the parameter estimation,and to realize the on shipborne calibration of SAHRS.