Accurate estimation of line-of-sight rate under strong impact interference effect

Abstract

In the process of the terminal guidance of a kinetic kill vehicle (KKV), it is very important to accurately estimate the line-of-sight (LOS) rate via the measurements of a target seeker onboard the KKV. The strong impact interference caused by the large lateral thrust produced by the thrusters on the KKV is a main factor that affects the measurements on the LOS angle. A method to estimate the impact interference and the LOS rate together via a Kalman filter is proposed to improve the estimation precision of the LOS rate. The observability of the system describing the missile-target relative motion model and the impact interference model is proved, and then a Kalman filter is designed. In the Kalman filter design, the continuous-discrete and two-stage filtering techniques are used because the system model is time-variant and high-order. Numerical simulation results show that by estimating the impact interference, the estimation precision of the LOS rate is increased, and so the miss distance of the KKV under the strong impact interference is reduced. The proposed continuous-discrete two-stage Kalman filter shows higher estimation precision and lower computational cost than the naive discrete augmented state Kalman filter.