Nonlinear robust inscribed angle guidance for stationary targets

Nonlinear robust guidance strategies, based on sliding mode control, are proposed to impose a pre-specified impact angle against stationary targets. The guidance strategies are based on the constant inscribed angle geometric rule, which enforces movement along an arc of a circle, and vary in the type of information needed for their implementation. Different information types are considered: information on inscribed angle only, information on both inscribed angle value and its rate, as well as complete information of inscribed angle dynamics. The guidance design does not require linearization thus enabling it to perform well in engagement scenarios far from the nominal one. Effect of uncertainties on the control effort of guidance strategies is analyzed. Simulation results are presented to validate and compare relative performance of the guidance strategies to other known guidance laws that can also enforce an intercept angle.