Research Of LOS Rate Estimation Method For Strapdown Imaging Seeker

With the development of strapdown inertial technology and imaging technology, strapdown imaging seeker has turn into the developing trend of modern missile seeker. However, compared with the traditional seeker using inertial platform, the line of sight(LOS) rate of strapdown seeker can not directly be measured. In addition, more measurement noise is induced due to the wide sighting field. In view of the aforementioned problems, this paper studies the LOS rate estimation method of strapdown imaging seeker.Firstly, coordinates are defined and body LOS coordinate is introduced. Then the transformation matrices among the coordinates and LOS rate decoupling expressions are deduced.Secondly, classical tracking method of missile and target are studied. Tracking simulations, using pursuit guidance law and proportion guidance law, are accomplished in order to get LOS rate, body LOS rate and correlative coordinate transformation matrix.Thirdly, the outliers existing in measurements are analyzed. Through amending"innovation"in the equations of Kalman filter, outlier-eliminating Kalman filtering algorithm is achieved. Simulation results show that outlier-eliminating Kalman filtering algorithm , which based on"innovation"amending, can effectively eliminate both the isolated outliers and patch-type outliers.Finally, through analyzing background noise, Gaussian-Laplace noise model is established. Then state equations and measurement equations are established in order to distill the LOS rate. As traditional extended Kalman filter(EKF) can adapt to neither complicated nonlinear equations nor nonGaussian noise, LOS rate estimation using particle filter(PF) and unscented Kalman filter(UKF) are studied.Simulation results show that LOS rate estimation, using UKF method for strapdown imaging guidance system, can meet both real-time and precision requirements.