Deadlock-Aware Control for Multirobot Coordination With Multiple Safety Constraints

Abstract

Multi-robot coordination in shared workspaces is prone to deadlocks, which can compromise operational capabilities and task efficiency. Accurately determining the timing and spatial locations of deadlocks is essential for effective resolution, yet remains challenging due to dynamic robot interactions and growing system complexity. To this end, a distributed deadlockaware control framework is proposed for robots to detect and avoid deadlocks while maintaining safe task execution. First, deadlocks are characterized by analyzing undesired equilibria in robot dynamics under safety constraints imposed by multiple stacked control barrier functions (CBFs). Our analysis reveals two critical properties: 1) Deadlocks occur at intersections of all active CBF boundaries, and 2) Deadlocks arise when robot stabilizing force are confined within the conical hull formed by active safety forces. These theoretical insights underpin a new detection method that identifies potential deadlocks from conflicts between safety requirements and task objectives. Furthermore, a reactive deadlock avoidance method is designed to help robots escape and prevent entry into potential deadlock regions by adaptively modulating the stabilizing force. A generalized workflow is established to systematically address deadlocks across various multi-robot tasks. Simulation and hardware experiments are conducted on robots collaborating in dense environments to validate the framework's effectiveness in preventing task failures caused by deadlocks.