Three-dimensional terminal angle constraint guidance law considering autopilot dynamic lag

Addressing the dynamic lag and multi-constraint problems in the interception of high-maneuverability aircraft, a second-order system model for three-dimensional interception guidance is constructed, and a terminal angle constraint guidance law is proposed. A finite time convergent third-order disturbance observer is proposed to address disturbances caused by target maneuvering. The system model is treated as an “observer-controller” system, and a non-singular finite time convergent controller is proposed based on the theory of super-twisting sliding mode control. In addition, considering the dynamic response of the autopilot, the system model is extended to fourth order. Based on backstepping and dynamic surface control theory, the line-of-sight (LOS) angle errors and LOS angular rates are controlled within the neighborhood of zero, achieving precise interception of the target. Finally, the good performance of the proposed guidance law is verified through simulations in different scenarios.