Optimal Guidance with an Intercept Angle Constraint for Varying Speed Adversaries

The paper proposes an optimal missile guidance law, which enables target interception while imposing a predetermined terminal intercept angle with varying missile and target speeds. Imposing the terminal intercept angle can be used to increase warhead lethally, to improve observability, and to intercept the target from less defended directions. The guidance law is derived for arbitrary order linear missile dynamics, using optimal control theory. Unlike previous optimal solutions, which usually assume constant missile and target speeds, arbitrary time dependent speed profiles of the adversaries are addressed to cope with more realistic scenarios. The problem is solved analytically and specific closed form results are provided for ideal missile dynamics and adversaries with constant axial accelerations. The performance of the proposed guidance law is investigated using a nonlinear two-dimensional simulation and the results are compared to an optimal guidance law that does not account for the target’s and missile’s speed changes. It is shown that the proposed guidance law can intercept the target with a negligible miss distance and intercept angle error and that the proposed guidance law is substantially better when the target and missile speeds vary.