Three-Dimensional Impact Angle and Time Control Guidance Law Based on Two-Stage Strategy

In this paper, a three-dimensional (3D) nonlinear guidance law is developed for attacking a stationary target with desired impact angle and time. The guidance law is divided into two stages as impact angle control guidance (IACG) and proportional navigation guidance (PNG). In the IACG stage, a sliding-mode guidance law is established to guarantee the satisfaction of the impact angle constraint, and in the second stage, the 3D PNG law is applied to ensure zero miss distance. The switch between the IACG and the PNG stages is determined by a guidance parameter related to the impact time constraint. By the virtue of Newton iteration method, an appropriate guidance parameter is obtained by solving an implicit nonlinear equality after a small number of iterations. Several numerical simulations are conducted to verify the feasibility and effectiveness of the proposed guidance law under different scenarios.