Optimal strategy for target protection with a defender in the pursuit

The conflict among three players, an attacker, a defender, and a target, in the pursuit-evasion strategy context is investigated. The problem is derived for a defender launching from the target with the assumption that the guidance laws of the attacker and defender are linear in form. During the endgame, the target lures the attacker close to the defender based on the attacker’s reaction to the target. Two kinds of optimal guidance laws for protecting the target from the attacker are presented first. Showing that the two kinds of guidance laws are flawed, a new optimal guidance law is subsequently derived. Considering that the players’ control efforts are bounded by reality, the relevant parameters corresponding to the optimal guidance laws also need to be analyzed. For adversaries obeying first-order dynamics, the performance of the guidance laws is simulated for different parameters, and under reasonable parameter choices, the simulation results show that the new optimal guidance law can enable the target to assist the defender in effectively intercepting the attacker