Archimedean spiral-based intercept angle guidance

This paper focuses on designing an intercept angle guidance law for the planar interception of a stationary target. The underlying geometrical rule isbased on an Archimedean spiral, which allows a pursuer to enforce a desired intercept angle or time by generating an appropriate spiral trajectory. An inherent advantage of using the proposed geometrical rule is that the required lateral acceleration to ensure interception is bounded throughout the engagement. The applicability of the geometrical rule is also analyzed against nonmaneuvering moving targets. The geometrical rule is implemented using a sliding-mode control-based nonlinear and robust guidance law. Using the proposed guidance law, the desired intercept angle is achieved in finite time. The theoretical results are validated through numerical simulations. The interception of the target with a specified intercept angle from different initial conditions and with various intercept angles from a given initial condition are shown. The robustness of the controller against disturbances and heading errors is also evaluated.