Sliding-mode guidance law with impact angle constraint accounting for autopilot lag

Based on the finite time convergence stability theory, a finite time convergent sliding-mode guidance law with terminal impact angle constraint is presented. By considering the dynamics of the acceleration autopilot of a missile as a first-order lag, the autopilot lag is designed in the guidance law. It is proved that the line-of-sight(LOS) rate can converge to zero before impact and the terminal flight path angle can meet the specified impact requirement in a finite time. Finally, simulation results show the effectiveness of the proposed method.