Towards A COLREGs Compliant Autonomous Surface Vessel in a Constrained Channel

TL;DR

This paper presents a comprehensive framework for COLREGs-compliant autonomous navigation of surface vessels in constrained channels, integrating sensor data processing, vessel tracking, and real-time path planning demonstrated on a real-world river mission.

Contribution

It introduces an integrated approach combining radar, INS, ENC, Kalman filtering, and path planning for autonomous vessels to navigate safely in complex environments.

Findings

Successful real-world demonstration on Charles River

Effective obstacle avoidance and vessel tracking

COLREGs compliance in dynamic scenarios

Abstract

In this paper, we look at the role of autonomous navigation in the maritime domain. Specifically, we examine how an Autonomous Surface Vessel(ASV) can achieve obstacle avoidance based on the Convention on the International Regulations for Preventing Collisions at Sea (1972), or COLREGs, in real-world environments. Our ASV is equipped with a broadband marine radar, an Inertial Navigation System (INS), and uses official Electronic Navigational Charts (ENC). These sensors are used to provide situational awareness and, in series of well-defined steps, we can exclude land objects from the radar data, extract tracks associated with moving vessels within range of the radar, and then use a Kalman Filter to track and predict the motion of other moving vessels in the vicinity. A Constant Velocity model for the Kalman Filter allows us to solve the data association to build a consistent model between successive radar scans. We account for multiple COLREGs situations based on the predicted relative motion. Finally, an efficient path planning algorithm is presented to find a path and publish waypoints to perform real-time COLREGs compliant autonomous navigation within highly constrained environments. We demonstrate the results of our framework with operational results collected over the course of a 3.4 nautical mile mission on the Charles River in Boston in which the ASV encountered and successfully navigated multiple scenarios and encounters with other moving vessels at close quarters.