Simulation of Obstacle Avoidance and Passage Navigation Using a Ship Cluster Behavior Model

Abstract

This paper presents a simulation study of the characteristics of obstacle avoidance and passage navigation by multiple ships forming a group. To make this possible, we added two new forces, i.e. obstacles avoidance force and scrape avoidance force to the previous model that only had four independent forces, i.e., goal attainment, contracting, expanding, and cluster collision avoidance forces. In this new model, maneuvering decisions of ship agents are computed by combining the above-mentioned six independent forces. The weight for obstacle avoidance force was determined based on the behavior characteristics of a single ship case. The simulation results revealed that collisions occur immediately before ships reach, and immediately after they have avoided an obstacle in case of avoiding an obstacle. When navigating through a passage, collisions occur immediately before and after entering a passage, and shortly after ships have left a passage. Also discussed in this paper are the time change of the cluster's emergent characteristics (mean distance, cluster configuration keeping ratio, number of collisions, aspect ratio) in passage navigation, the effect of passage width on the cluster width, and the impact of way point location in entering a passage.