Accuracy evaluation of camera-based position and heading measurement system for vessel positioning at a very close distance

Abstract

In this study, we propose a measurement system consists of two pairs of multiple cameras mounted on a pan-tilt unit and a landmark installed on a target side. The purpose of the proposed system is to measure relative position and heading angle of a vessel to a target at a close distance, in order to reduce collision risks by automation of vessel positioning that requires high measurement accuracy and rate. To achieve such measurement, cameras that have wide sensing range and high angular resolution are used instead of GPS, radars, or laser sensors. The proposed system also has the ability of accurate and fast measurement of the distance and direction angle to a target by applying a simple and robust target detection method. The position and heading of a vessel are determined from two pairs of the distance and direction angle. To evaluate the measurement accuracy of the proposed system, we measured position and heading of the system relative to landmarks on several conditions including positional displacement and rotation. The experimental results demonstrate that the proposed system can be used for automation of vessel positioning at a close distance.