Follow-the-Leader Guidance, Navigation, and Control of Surface Vessels: Design and Experiments

Abstract

A novel follow-the-leader approach for azimuthdriven vessels is devised and experimentally tested in a model-scale outdoor scenario. The vessels are equipped with global navigation satellite and inertial navigation systems. A line-of-sight algorithm ensures the yaw-check ability of the follower vessel along the leader's path, while a speed-regulation allows to track its velocity. Track generation, guidance, navigation, and control modules are designed and assembled to be executed on-board in real time. The results of an outdoor experimental campaign are illustrated to show the effectiveness of the proposed approach. Index Terms-Azimuth-drive propulsion, escort tugs, follow-theleader control, line of sight (LOS), track keeping. I. INTRODUCTIONM OST of the operational life of sailing vessels consists in tracking a predetermined path in restricted and open waters, according to complex traffic management constraints and risks [1]. The capability of forming convoys and following a leading target-vessel within its wake is a valuable feature in both blue seas and busy/restricted areas, such as inland waterways and harbors [2]. In this scenario, the two main challenges are to steer, while keeping off-track tolerances, and to tune the speed according to the leader. Such objectives need to be reached with high accuracy and are crucial to safely exploit the viable inland waterways' routes and minimize the sailing delays and accidents [3], [4].

A Dynamic Programming Approach to the Collision Avoidance of Autonomous Ships

“…The representation of a maneuver by waypoints and legs is intelligible to seafarers, and the decision support system can propose it to the officer on the watch, who can understand it and decide whether to acknowledge it. Then, the new sequence of waypoints is taken over by a motion control system, for example, one based on Line of Sight [29,30], which determines, based on GNSS localization, the necessary propulsion and steering actions to track the course according to the ship's dynamics with a reasonably low track error. The layered architecture of an autonomous navigation or navigation support system.…”