Near-Optimal Evasion from Realistic Pursuers Employing Modern Linear Guidance Laws

Target evasion is a very challenging problem because interception missiles usually have substantial agility and maneuver advantages over the target. This paper proposes near-optimal evasion strategies that exploit the two main weaknesses of the pursuer to maximize the miss distance. The first is the inherent time delay of the evader’s acceleration estimate, and the second is the pursuer’s acceleration bound. In the derivation, the evader is assumed to have perfect information on the pursuer’s states, parameters, and guidance law. The pursuer is assumed to have perfect information on the evader’s parameters and states. However, the pursuer’s estimate of the evader’s acceleration is assumed to have a pure delay. Finally, the missile and the target are assumed to have arbitrary order linear dynamics with bounded acceleration commands. The problem is posed as a bounded optimal control problem, and the necessary analytical optimality conditions in the saturated and unsaturated missile acceleration regions are derived. The problem is then solved iteratively using backward and forward propagation of the co-state and state dynamics until the solution converges. The evasion strategies are evaluated in linear, deterministic, and stochastic Monte Carlo simulations. It is shown that the proposed evasion strategies that exploit the missile’s saturation limits and estimation delay have dramatically better evasion performance than state-of-the-art evasion strategies that only exploit the estimation time delay.