High precision 3-D nonlinear variable structure guidance law for homing missile

Three-dimensional relative motion model of missile and target is established,it considers the target's acceleration as the input disturbance and then derives the strongly robust adaptive guidance law based on zeroing normal speed of LOS (line-of- sight).3-D nonlinear variable structure guidance law for homing missile based on zeroing speed of LOS angle is presented in this paper,the adaptive law can estimate the uncertain boundary of target's maneuvering acceleration.The more general combat environment is considered in the algorithm,so it is depended on the hypothesis of the linearization near collision course,and overcomes the influence that the estimation error of the surplus time brings to the guidance precision.The simulating results indicate that the guidance law exhibits strong robustness properties against disturbances from target's maneuvers.The guidance algorithm is very simple and never needs the boundary of the acceleration of target,so it is more convenient for comprehension and practical implementation.