Nonlinear reentry guidance law guaranteeing convergence before attainment of desired line-of-sight range

Nonlinear guidance law guaranteeing convergence before attainment of desired line-of-sight (LOS) range in the background of reentry vehicle attacking a moving target on the ground is studied in this paper. Initially, a novel guidance model is established in which LOS range is treated as an independent variable, describing the relative motion between the vehicle and the target. The guidance model includes two differential equations that describe LOS's pitch and yaw motions in which the pitch motion is separately decoupled. Subsequently, guidance laws with disturbance suppression of the pitch and yaw motion of LOS are designed separately, and presented in the form of normal overload. Compared with traditional guidance laws, the proposed one guarantees that LOS angular rate converges to zero before LOS range decreases to the desired value. Finally, the correctness and validity of the guidance model and guidance law are verified by numerical simulation. The guidance model and guidance law proposed in this paper provide a new way for the design of fast convergent guidance law.