Impact angle control guidance law considering the seeker’s field-of-view limits

Abstract

In this dissertation, guidance problems with impact angle constraint and seeker’s filed-of-view (FOV) limits are investigated. Recently, in a variety of guided missiles, impact angle control to satisfy the terminal flight path angle has been widely used to improve the kill probability and to maximize the warhead effect. However, since the impact angle control causes missile trajectories to be highly curved, the missile can miss the target within the seeker FOV, leading to the mission failure. Therefore, considering the seeker’s FOV limits is a key issue for missiles with the limited seeker’s FOV to implement the impact angle control guidance law. This dissertation presents two different guidance laws considering the impact angle constraint and seeker’s FOV limits simultaneously: one is an optimal impact angle control guidance law with the limitation of the seeker’s FOV, and the other is a composite guidance law for impact angle control within the seeker’s FOV limits. To handle the seeker’s FOV limits in the homing guidance problem, under the assumption that angle-of-attack (AOA) is small, a look angle, which is defined as the angle between the velocity vector and the line-of-sight (LOS), is considered as an inequality constraint. The optimal impact angle control guidance law considering the seeker’s FOV limits is derived using optimal control theory with a state variable inequality constraint. The proposed optimal guidance law is made of three types of optimal acceleration commands as the missile-target relative range: the first command for the initial guidance phase is to reach the maximum look angle of the seeker, the second for the mid-guidance phase is to keep the seeker look angle constant, and the third for the final guidance phase is to intercept the target with the desired impact angle. The composite guidance law is derived based on the characteristics of pure proportional navigation (PPN), and it is designed for passive homing missiles. The proposed c...