Analytical Solution for Impact-Angle-Constrained Guidance with Flight Speed and Trajectory Length Prediction

This paper proposes an analytical guidance law for unmanned aerial vehicles (UAV) to achieve the desired impact angle on a stationary target and provide the prediction of flight speed and trajectory length. Firstly, an impact angle guidance (IAG) law is developed based on the framework of conventional proportional navigation guidance (PNG). The novelty of the proposed guidance law is that its trajectory shape and length are independent of UAV speed variation. Then, the flight speed and trajectory length are obtained by utilizing the small leading angle assumption and the drag polar model. Unlike most similar studies, the proposed methods have significant potential to address the impact time control problem and incorporate cooperative guidance laws under a more practical scenario, in which the speed of the UAV is continuously varying subject to aerodynamic drag.