Nonlinear H_∞ robust guidance law for homing missiles

This paper proposes an H_∞ robust guidance law for homing missiles with nonlinear kinematics in the homing phase. Unlike conventional approaches where target's acceleration is often assumed to be known or needs to be estimated in real time, the proposed robust guidance law can achieve performance robustness in the absence of target's acceleration information and under variations of the initial conditions of engagement. The most difficult and challenging task involved in applying nonlinear H_∞ control theory is the solution of the associated Hamilton-Jacobi partial differential inequality. In this paper we show that the Hamilton-Jacobi partial differential inequality of the missile guidance problem can be solved analytically with simple manipulations. The numerical simulations show that the H_∞ robust guidance law exhibits strong robustness properties against disturbances from target's maneuvers and variations in initial engagement conditions.