Sliding mode-based intercept guidance with uncertainty and disturbance compensation

This paper presents a missile intercept guidance law that can account for uncertainty and disturbance. The proposed guidance law is developed based on a novel second order sliding surface, along with an uncertainty and disturbance estimator. The proposed sliding surface is invariant for the non-impact angle constraint case as well as the impact angle constraint case. The sliding surface guarantees finite time convergence of the line-of-sight (LOS) rate and (if specified) the LOS angle error, characterized by a simple function of time-to-go. Furthermore, the proposed strategy is also effective against a maneuvering target. The line-of-sight rate convergence property can be adjusted using only one parameter that makes the design process simple. Potential of the proposed guidance laws is demonstrated with some simulations.