Research On SINS/DVL Flitering Method

SINS/DVL is an integrated navigation system which based on Strapdown Inertial Navigation System(SINS)and Doppler Velocity Log(DVL),using filter technology to achieve the desired navigation accuracy.In this paper,aming at the output information's error of the navigation system is periodic oscillation and accumulated,adding damping principle and smoothing principle in the filter of linear and nonlinear SINS/DVL system respectively.Rearching on the Kalman filter and backword-smoothing Cubrature Kalman filter under the damping state of the SINS/DVL system.Firstly,basic knowledge and working principle of the inertial navigation systems and SINS are introduced and detailed deduced,establish the linear error equation of SINS.In order to prevent the periodic oscillation of the output information's error of navigation system,a damping concept is introduced,analysis the principle of SINS under the damping state and establish the damping inertial navigation error equation.The working principle of the doppler velocimeter(DVL)is introduced and deduced,establish the speed measuring error equation of DVL.Secondly,for the output information's error of the linear SINS/DVL system are accumulated over time and vibrate,damping Kalman filter method is proposed.Establish the state matrix and measurement matrix of the damping Kalman filter,the simulation of SINS/DVL system under the damping Kalman filter were completed.The results show that damping Kalman filter can restrain the periodic oscillation of of the system output information's error,and compared with the basic Kalman filter,the accuracy of the output information's error of the linear SINS/DVL system is higher and more stable.Finally,because in the practical engineering the environment is bad,there are many error sources,there is a big attitude error angle between the navigation coordinate and "platform" coordinate,resulting in the error model of the SINS system there is obvious nonlinear characteristics,so need to research on the nonlinear filtering algorithm of the SINS/DVL system.In this paper,based on the basic CKF filter,the principle of backward-smooth is introduced,this principle is a recursive computation for the amount of filtered,as the majority error of the system has been removed by the forward filter,if regard the value of backwardsmooth as the initial value of filter again,it can improve the precision of the filter effectively.So the backward-smooth CKF is proposed,the principle is deduced,and the simulation of SINS/DVL system under the backward-smooth CKF were completed.The results show that compared with basic CKF filter,the backward-smooth CKF algorithm can make the estimation precision is higher.Because filtering algorithm can only make the position error and velocity error of navigation system is improved,but have less effect on the attitude error.the damping principle is the effective method to improve the system attitude error precision and can restrain the periodic oscillation of of the system output information's error.Therefore the backward-smooth CKF algorithm of the SINS/DVL under the damping state is proposed and the simulation was completed.The results show that this method not only can improve the accuracy of output information's error of SINS/DVL system and can restrain the periodic oscillation of the error effectively.