COLREGS-Constrained Real-time Path Planning for Autonomous Ships Using Modified Artificial Potential Fields

TLDR

Automatic navigation systems for ships could benefit from advanced path‑planning algorithms. This paper presents a real‑time deterministic path‑planning method for autonomous ships or USVs in complex dynamic environments. The method uses a modified artificial potential field with new repulsion functions and virtual forces that incorporate COLREGS constraints for collision avoidance with dynamic targets and static obstacles. Simulations demonstrate that the method is fast, effective, deterministic, and can handle multiple moving targets and stationary obstacles while accounting for unpredictable ship strategies.

Abstract

This paper presents a real-time and deterministic path planning method for autonomous ships or Unmanned Surface Vehicles (USV) in complex and dynamic navigation environments. A modified Artificial Potential Field (APF), which contains a new modified repulsion potential field function and the corresponding virtual forces, is developed to address the issue of Collision Avoidance (CA) with dynamic targets and static obstacles, including emergency situations. Appropriate functional and safety requirements are added in the corresponding virtual forces to ensure International Regulations for Preventing Collisions at Sea (COLREGS)-constrained behaviour for the own ship's CA actions. Simulations show that the method is fast, effective and deterministic for path planning in complex situations with multiple moving target ships and stationary obstacles and can account for the unpredictable strategies of other ships. The authors believe that automatic navigation systems operated without human interaction could benefit from the development of path planning algorithms.