Three-Dimensional Helical Guidance With Impact Time Constraints

This article addresses the 3-D helical guidance problem for attacking a stationary target. Different from the existing works, a 3-D helical guidance law is developed to cater for impact time constraints. First, an analytical time-to-go estimation expression is proposed, and a vector guidance law is designed by using an inverse design method to ensure accurate time-to-go prediction. Furthermore, a helical term is incorporated to induce helical maneuvers, enhancing the system observability without compromising time-to-go estimation accuracy. To broaden applicability, a biased feedback command is augmented to accommodate diverse impact time constraints, with a rigorous convergence proof provided via Lyapunov theory. In addition, an unmanned aerial vehicle-based pure physical system and a fixed-wing hardware-in-the-loop system are introduced to provide experimental validation. Finally, the effectiveness and reliability of the proposed guidance law are confirmed through both numerical simulations and physical experiments.