Target maneuver models for improved homing guidance

This dissertation considers the development of a guidance law for a homing missile using angle-only measurement and where the target is highly maneuverable. A new stochastic dynamic target model is proposed on the assumption that certain targets execute evasive maneuvers orthogonal to their velocity vector. Along with this new acceleration dynamic model, the orthogonality is also enforced by the addition of a fictitious auxiliary measurement. The target states are estimated by the modified gain extended Kalman filter, and the angular target maneuver rate is constructed on-line. A guidance law that minimizes a quadratic performance index subject to the assumed stochastic engagement dynamics that includes state dependent noise is derived. This guidance law is determined in closed form where the gains are an explicit function of the estimated target maneuver rate as well as time to go. The numerical simulation for the two-dimensional angle-only measurement case indicates that the proposed target model leads to a remarkable estimation of the target states. Furthermore, the effect on terminal miss distance using this new guidance scheme is given and compared to the Gauss-Markov model. The concepts of the circular target model and kinematic constraint are extended to the development of the spherical target model for the three dimensional case where the acceleration is assumed to lie in the plane perpendicular to the velocity vector. A guidance law that minimizes a quadratic performance index is also determined in closed form as an explicit function of the estimated target maneuver rate and the time to go. The numerical simulation results for various types of intercept scenarios indicate that the current target model leads to reliable performance in estimation of target states and terminal miss distance.