Control of terminal engagement geometry using variable structure guidance law with impact angular constraint

This paper proposes a new guidance law for the impact angle control, using the variable structure control theory. The guidance law has the ability to simultaneously achieve design specifications on miss distance and final missile-target relative orientation. The latter specification may be used to enhance the performance of warheads whose effectiveness is influenced by the terminal encounter geometry between missile and target. The variable structure guidance law is parameterized with terminal conditions of miss distance and terminal encounter angle. Feasibility of the variable structure guidance law is demonstrated by the simulation. According to the simulation results, the guidance law is shown to perform well against an air target performing evasive maneuvers. The specified zero aspect terminal encounter angle is achieved while simultaneously minimizing the miss distance.