Two Hierarchical Guidance Laws of Pursuer in Orbital Pursuit–Evasion–Defense Game

Abstract

In this study, differential game theory was applied to propose two guidance laws of a pursuer in an orbit pursuit–evasion–defense game. One was a conservative guidance law of maneuvering to absolute safety before pursuing the evader, and the other was a radical guidance law of playing with the defender only when necessary. Both guidance laws enable the pursuer to avoid the defender while pursuing the evader, but the radical guidance law reduces the pursuit time by moving the pursuer closer to the defender. The pursuer, defender, and evader are all spacecraft carrying three-axis thrusters that can provide independent thrust in three directions. The proximity dynamics processes of the participants were described by the Clohessy–Wiltshire equations. A method for solving the time-to-go analytically was proposed by simplifying the dynamics model to meet real-time requirements. The effectiveness of the two guidance laws was verified by numerical simulations, and the differences between the two laws were analyzed.