Adaptive sliding-mode guidance law with finite time convergence

Conventional guidance laws which are designed based on Lyapunov theorems can not ensure the finite time convergence of guidance system. A novel second-order sliding mode control approach with finite time convergence is presented through the use of sliding-mode control theory and is used in a maneuvering target interception scenario for a guidance law design. The first part of this guidance law has the similar structure of proportional navigation with time-varying effective navigation ratio, so that line-of-sight rate is approaching zero. However, the extension part of this guidance law has the features of line-of-sight (LoS) shaping, finite time convergence of sliding mode surface and robustness to the variation of interception missile and target velocities. The simulations with nonlinear motion model are carried out for two typical target maneuvers. The results show that this guidance law can intercept the target effectively and can satisfy the above features; in addition, it has certain adaptability to target maneuvering forms.