Robust command-to-line-of-sight guidance via variable-structure control

This paper addresses the nonlinear control problem of guiding a point defense missile toward the line-of-sight between a defending ship and a sea-skimming missile, variable-structure control theory is employed to solve the problem. The resulting guidance algorithm consists of a third-order sliding surface. It forces the missile to converge rapidly toward the line-of-sight, avoiding dangerous undershoots. We demonstrate that in the context of a realistic engagement scenario, the algorithm exhibits sufficient robustness margins