Back-stepping guidance law with autopilot lag for attack angle constrained trajectories

Aiming at the requirement for the attack angle near impact required to be controlled for some guided weapons and the unfavorable effects of the lag of autopilot on guidance accuracy, a novel terminal back-stepping guidance law with attack angle constraint is proposed in consideration of the lag of autopilot. Firstly, a virtual control law is designed for the second-order subsystem by applying the generalized integrator back-stepping theorem presented in this paper in connection with the feedback linearization technique. Furthermore, the guidance law with attack angle constraint for the case of the lag of autopilot is derived by utilizing the back-stepping method again, and the exponentially convergent characteristics of the proposed guidance law with respect to both line-of-sight angle and angular rate is detailedly proved by using Lyapunov stability theory. In simulation of an application example, the specific approach to implementing the proposed guidance law is addressed, the guidance performance of this law is compared with other laws, and the guidance effect of it in different operation tasks is tested. Simulation results demonstrate that the proposed algorithm provides the good performance and possesses the great application promotion value in engineering.