Optimal impact angle guidance law with barrier constraint

This paper presents an optimal guidance law for missile to achieve desired impact angles on a stationary target while accommodating the barrier constraint. The proposed guidance law consists of two parts: a baseline guidance command for intercepting the target with desired impact angles, and a bias command to prevent collision with the barrier. Specifically, the baseline guidance command is derived by solving a linearized optimal control problem, and its explicit trajectory solution is also obtained for collision estimation. The bias command is designed using a novel guidance error that is defined based on the geometrical relationship between the barrier and the proposed explicit trajectory solution. The new guidance law can be easily implemented to a variety of practical engagement geometries, resulting in successful collision avoidance and minimal control efforts. Its effectiveness and robustness are demonstrated via extensive numerical simulations.