Multi-ASV Collision Avoidance for Point-to-Point Transitions Based on Heading-Constrained Control Barrier Functions with Experiment

Dear Editor, Collision avoidance is critical for safe operations of multiple autonomous surface vehicles (ASVs). It is a challenging task to design collision-free control laws to ensure safety, especially in a crowded sea environment. This letter presents a collision-free point-to-point transition strategy for multiple ASVs subject to static obstacles, dynamic obstacles and neighboring ASVs based on control barrier functions (CBFs). Existing CBFs consider only the position and not the heading, which makes it difficult to apply them to under-actuated ASVs. To address it, a heading-constrained CBF is proposed to design a yaw rate control law for avoiding collision with static obstacles, dynamic obstacles and vehicle neighbors. A quadratic program (QP) problem is formulated to compute the optimal yaw rate for each ASV such that the reach-avoid task can be achieved with safety guarantees. Both hardware-in-loop (HIL) simulation and field experiment results are given to substantiate the efficacy of the proposed heading-constrained CBFs.