Research On Fiber Optic Gyro Filtering Algorithm And Inertial/Visual Integrated Navigation

The inertial navigation system(INS)can realize the navigation and positioning of the carrier only by relying on the measurement information of the inertial components,and has strong autonomy and anti-interference ability.The fiber optic gyroscope(FOG)has become the main inertial component of INS due to its light weight,high reliability,and fast sampling frequency.The output signal of FOG contains various random noises,which need to be filtered and weakened,thereby improving the accuracy of the data.Simultaneously,the INS has its own drift and digital error,which makes the attitude angle and velocity obtained by the integral operation drift over time,especially the position divergence obtained by the quadratic integration.Through the fusion of inertial/visual data,an inertial vision integrated navigation system can be constructed,which can make up for the lack of navigation and positioning accuracy of the inertial navigation system and improve the accuracy of the inertial navigation unit.This paper studies the filtering algorithm of the output signal of the FOG,and discusses the data fusion algorithm of inertial/visual integrated navigation system on this basis.The specific research content of this article is as follows:1.This article describes the conversion relationship between the coordinate systems of the strapdowm inertial navigation system,the method of calculating the attitude of the carrier,and the update equation and error equation of the inertial navigation.The Allan variance is used to quantify and separate each random noise of the gyroscope,and analyze the signal noise characteristics of the fiber optic gyroscope.The output data of the FOG is analyzed in the time domain,and the random error model of the gyroscope based on Allan variance analysis is established.2.In order to eliminate the random error of the FOG signal and restore the real signal to the greatest extent,a filtering algorithm based on EMD-SVD fiber optic gyroscope is adopted.Decompose the signal of FOG into multiple intrinsic mode functions(IMF)through empirical mode decomposition(EMD).Using continuous mean square error(CMSE)and Mahalanobis distance(MD)correlation theory to calculate two index parameters,the output signal of fiber optic gyroscope is divided into noise IMFs,mixed IMFs and information IMFs.And the signal reconstruction scheme is designed.The EMD-SVD filtering algorithm is used to filter the mixed IMFs one by one,and the signal is reconstructed to obtain the filtered signal.The filtering algorithm proposed in this paper can effectively suppress the drift of the gyroscope signal and improve the accuracy of the gyroscope's calculation.3.Based on the fiber optic gyroscope filter algorithm,the advantages and disadvantages of inertial navigation and visual navigation are analyzed.Based on the multi-rate kalman filter(MKF)fusion inertial/visual integrated navigation,the state model and measurement model of the combined system are established for the problem of inconsistent sampling periods when the dual systems are fused,and simulation experiments are carried out.Simulation experiments show that this method has better convergence effect and higher navigation accuracy.