A method for line of sight angle rate reconstruction based on strapdown seeker

The line of sight (LOS) information which detected by strapdown seeker is coupled with missile attitude information. On the other hand, since the instantaneous field of view is wider, the noise levels of strapdown seeker are higher than those of conventional gimbals seeker. According to the relationship among coordinates which are used to describe motion of missile, analysis of the attitude decoupling algorithm was deduced in detail. Based on the proposed algorithm, the LOS reconstruction filter was designed to obtain more precise line of sight angle, where, the theory of Central Difference Kalman Filter (CDKF) which based on Central Difference (CD) method was applied to deal with the filtering problem of nonlinear system. Compared with EKF, the solving of Jacobi matrixs can be avoided and only one adjustable parameter h was introduced which leads to a reduction of the computational cost. Based on this, the algorithm was suitable for engineering application. The results of computer simulation confirmed the validity of the proposed inertial LOS reconstruction filter, which can be used to improve the precision of inertial LOS and LOS rate estimation. The method meanwhile can be used as a new method to estimate inertial LOS rate.