Line-of-Sight Rate Estimation Based on Strong Tracking Cubature Kalman Filter for Strapdown Seeker

Abstract

This paper addresses the inability of the strapdown seeker to indirectly measure line-of-sight (LOS) rate and the strongly nonlinear relative motion equations of missile and target. Strong tracking theory is combined with cubature Kalman filter (CKF), and a novel nonlinear filter for LOS rate estimation is presented; this filter is called the strong tracking CKF (STCKF). On the basis of the relative motion relationship of missile and target, the LOS rate reconstruction model is derived. Then, the STCKF algorithm is proposed by introducing a suboptimal fading factor into the predicted error covariance of the CKF. Finally, the validity and feasibility of the proposed algorithm are verified by simulation. Simulation results show that the proposed STCKF maintains the strong tracking ability for abrupt state changes. A comparison with CKF shows that STCKF can improve the LOS rate estimation precision for a strapdown seeker with better robustness and adaptability.