Multi-Robot Defense with Visibility Constraints: A Relay-Based Approach for Guarding Multiple Targets

This paper addresses the multi-player, multitarget guarding problem, where multiple robots with limited visibility defend several targets against a single intruder. The intruder selects a target and attempts to infiltrate, while the defenders aim to intercept it. We propose a semi-cooperative defense strategy that relies solely on relative position to address this challenge. First, we partition the state space of the multiplayer system and design relay defense strategies based on initial conditions. Second, we introduce a multi-target allocation scheme, incorporating risk metrics and a nonlinear feedback control strategy that adapts to different state spaces. Finally, we provide sufficient conditions for the defenders to successfully intercept the intruder, considering their capture radius. The effectiveness of our approach is validated through theoretical analysis and experiments with ground mobile robots.