Abstract:

When the air defense missile intercepts the ultra-low altitude target, the existence of the multipath effect will greatly reduce the detection and tracking accuracy of the missile radar seeker. In order to reduce the influence of the multipath interference, the line of sight (LOS) angle of the missile and target can be constrained near the Brewster angle, but most researches only restrict it to the Brewster angle at the intersection of missile and target. Based on the characteristics that mode predictive control can track expected LOS angle, a mode predictive guidance law is designed. For the influence of the maneuvering disturbance of the super-low altitude targets on the guidance accuracy, the sliding mode disturbance observer is designed to estimate the acceleration of the target. Finally, a composite guidance law is designed based on the estimation of target acceleration and the mode predictive guidance law. And the results show that the composite guidance law can ensure the interceptor track and attack the super-low altitude target by Brewster angle, converge the LOS angular rate to zero, reduce the multipath interference to minimum and improve the interception accuracy.

Key words: multipath effect, Brewster angle, mode predictive control, sliding mode disturbance observer