Development and Testing of an Unmanned Surface Towing System for Autonomous Transport of Multiple Heterogeneous Underwater Vehicles for Seafloor Survey

Abstract

Simultaneous operation of multiple autonomous underwater vehicles (AUVs) can increase seafloor mapping efficiency. However, AUVs typically rely on support vessels with an operations crew for transport to sites of interest and supervision during their dives. This is costly and limits the scalability of AUV-based seafloor mapping. This paper describes a robotic system that can transport AUVs from shore and deploy them in a survey area located offshore, without the need for a crewed support vessel. We clarify the functional requirements for ship-free AUV operations and propose a concept that allows a single autonomous surface vehicle (ASV) to transport, release, and monitor multiple large and heterogeneous AUVs. The proposed system uses towing modules that can be connected in parallel and can accommodate a variety of pre-existing ASVs and AUVs. A full-scale system was developed and tested during sea trials in the Mediterranean Sea off Greece, to verify basic functionality and gather data on the impact of towing multiple AUVs on ASV endurance and range. Results of these trials and lessons learned are discussed.