Integrated Midcourse-Terminal Guidance with Delayed Target Selection

This paper proposes an integrated midcourse-terminal guidance methodology for a trailing pursuer in a Shoot-Shoot-Look scenario. We consider the case of a pursuer implementing given standard guidance laws for the midcourse and terminal phases. These engagement stages are separated by a predefined decision time, at which the pursuer allocation is determined. The pursuer’s position and heading at the decision time, referred to as a handover point, is optimized with respect to a tradeoff between the expected miss distance and control effort. Since the pursuer uses known given guidance laws, the handover point is the only optimization parameter of the problem. We propose a computationally efficient approach to evaluate the performance index online for a set of candidate decision points sampled from the pursuer’s reachable set at the end of the midcourse stage. Specifically, for the terminal phase, we develop the performance index representation using a limited number of sensitivity functions, which relate to variations in initial conditions and evader maneuver and can be computed offline. This terminal phase cost evaluation procedure is applicable for a class of linear time-varying systems with a quadratic cost. The proposed methodology is exemplified for minimum-time midcourse trajectories and proportional navigation terminal guidance law.