RingBreak: A Lightweight Decentralized Controller for Symmetry Breaking in Multirobot Intersection Navigation

Reciprocal waiting can stop decentralized robots at symmetric intersections even when local commands maintain separation. RingBreak uses a local conflict core estimate, queueing, clockwise orbiting, release point recovery, and an empirical velocity projection to restore goal-directed motion. Its transition conditions and contact metric are specified for reproducibility. On six fixed layouts repeated with three controller seeds, RingBreak completed 18 of 18 runs without contact; an MPC-CBF deadlock auction implementation completed 6 of 18 without contact. In 20 paired head-on and four-way conflict layouts, RingBreak and a tuned goal-directed artificial potential field (APF) controller both completed every run without contact, but RingBreak had a shorter mean run time (19.24 versus 35.19 s). A separate evaluation independently perturbed starts and goals in seven patterns. Both methods completed 60 of 70 such trials without contact; APF had a shorter mean run time (34.38 versus 38.97 s), and both usually timed out at the walled intersection. Within RingBreak, removing release reduced contact-free completion to 19 of 70, and removing separation projection reduced it to 3 of 50. These results support the faster clearance of the tested reciprocal conflicts and do not provide a general advantage or a formal safety or deadlock-freedom guarantee.