Study on three-dimensional nonlinear robust guidance laws

In intercepting maneuvering targets in the air by missiles,the relative movement of the missile and the target is nonlinear and very complex.We built up a three-dimensional model in a spherical coordinate system for describing the relative movement of them.A new 3D nonlinear robust guidance law is derived aimed at interception of the highly maneuvering targets.The guidance law is developed based on the theory of control Lyapunov functions and Input-to-State Stability(ISS) notion,a tool for disturbance rejection.The guidance algorithm is very simple and needs not the boundary of the acceleration of target.It has less intercepting time and stronger robustness properties than the conventional proportional navigation.The simulation results indicate that the guidance law exhibits strong robustness properties and good tracking performance against disturbances from target's escape maneuvering.