Cooperative Capture Strategy for a Group of Slower UAVs to Intercept One Faster Intruder in 3-D Space

This paper investigates a reach-avoid game between a group of unmanned aerial vehicles (UAVs) and one faster intruder in 3-D space. The intruder intends to enter a goal area without being captured, whereas the UAVs try to capture the intruder before it enters. Firstly, we analyze the scenario of one slower UAV against a single intruder, identifying the dominant area of the slower UAV for successful capture using the properties of the Apollonius sphere. These findings are then applied to the engagement between a group of UAVs and the intruder, transforming the multiplayer game from a traditional game-theoretic framework to a swarm control problem. This involves coordinating the UAVs to ensure their joint dominant areas cover the intruder's potential paths and approach the intruder. A nominal capture control law integrating covering, containment, and proximity control components is then proposed to achieve these goals. Besides, this nominal control law is integrated with a control barrier function within a quadratically constrained quadratic program framework, which allows for optimizing the nominal control law to prevent the formation of a dominant blind zone and increase capture probability. Finally, simulations are conducted to verify the effectiveness of the proposed algorithm.