Impact time control guidance law with large impact angle constraint

The problem of impact time control with large impact angle constraint is addressed. The dynamics of impact time error under the biased proportional navigation based impact angle control guidance law is first derived for the case of large impact angle constraint. Based on the impact time error dynamics, an additional control term is designed to drive the impact time error to converge in finite time. The resultant impact time and impact angle control guidance law comprises the biased proportional navigation based impact angle control guidance law and an additional term. The first term is used to achieve zero miss distance with the designated impact angle, and the second term is used to control the impact time. Compared with the existing impact time and impact angle control guidance law, which is shown to be only applicable for the case of small impact angle constraint, its application is not limited by the magnitude of the designated impact angle. Finite time convergence of the closed-loop guidance system under the proposed impact time and impact angle control guidance law is proved. Numerical simulations are performed to verify the effectiveness of the proposed impact time and impact angle control guidance law, especially for case of large impact angle constraint.