Guidance Information Estimation for Strapdown Imaging Seeker of Tactical Missile Guided by Optimal Guidance Law

Strapdown imaging seeker has the advantages of high reliability and simple structure. The major disadvantage is that inertial line of sight rate is not directly available for the implementation of proportional navigation, and the uncertainty of seeker scale factor inevitably produces a parasite loop which severely degrades guidance performance. In this paper, a guidance system model of strapdown imaging seeker based on optimal guidance law (OGL) is constructed. The wide field of view of seeker results in nonlinearity of measurement equations, so an extended Kalman filter (EKF) algorithm is proposed to estimate the target state information required by OGL. The seeker scale factor error is estimated and compensated in the proposed algorithm. Numerical simulation results show that the EKF algorithm can estimate guidance information and scale factor error when the seeker scale factor is considered in the measurement equations. The influence of parasitic loop coupling on guidance system can be eliminated by compensating scale factor error of seeker, and the stability and precision of guidance system can be improved.