Differential Game Guidance Law for Interceptor Missiles with a Time-varying Lateral Acceleration Limit

Abstract

A guidance law for an interceptor missile with a time-varying lateral acceleration limit is developed using differential games formulation with bounded controls. If an interceptor has axial acceleration and its lateral acceleration is generated by the aerodynamic lift, its lateral acceleration limit will vary with time due to its time-varying speed and the air density varying with altitude. This time-varying lateral acceleration limit property can also be obtained by designs of the time-varying sum of jets’ thrust when the interceptor is steered by divert reaction jets. The effect of this time-varying limit is investigated in this paper. The results indicate that the time-varying design of this limit leads to cooperation between the mid-course and terminal homing phase, and yields an improvement in homing accuracy. The effectiveness of this guidance law is demonstrated in a realistic ballistic missile defense scenario. It is shown that the proposed guidance law guarantees admissible accuracy, and is robust for the target maneuver commands and the delay in the estimation process of the target maneuvers. Furthermore, it provides better homing performance compared to the conventional law if the estimation delay is longer than a certain degree.