Distributed Control Barrier Functions for Safe Multi-Vehicle Navigation in Heterogeneous USV Fleets

TL;DR

This paper introduces a distributed control barrier function-based safety filter for heterogeneous USV fleets, enhancing collision avoidance by assuming worst-case behaviors and integrating with COLREGS in real-time scenarios.

Contribution

It develops a novel distributed safety control method using control barrier functions tailored for heterogeneous vessel fleets, validated through simulations and real-world experiments.

Findings

The approach is effective across different vessel types.

It is robust to uncooperative human-operated vessels.

Combining CBF and COLREGS yields optimal safety and efficiency.

Abstract

Collision avoidance in heterogeneous fleets of uncrewed vessels is challenging because the decision-making processes and controllers often differ between platforms, and it is further complicated by the limitations on sharing trajectories and control values in real-time. This paper presents a pragmatic approach that addresses these issues by adding a control filter on each autonomous vehicle that assumes worst-case behavior from other contacts, including crewed vessels. This distributed safety control filter is developed using control barrier function (CBF) theory and the application is clearly described to ensure explainability of these safety-critical methods. This work compares the worst-case CBF approach with a Collision Regulations (COLREGS) behavior-based approach in simulated encounters. Real-world experiments with three different uncrewed vessels and a human operated vessel were performed to confirm the approach is effective across a range of platforms and is robust to uncooperative behavior from human operators. Results show that combining both CBF methods and COLREGS behaviors achieves the best safety and efficiency.