On the Sea Test of Autonomous Sea Surveillance by Using the Swarm of Unmanned Surface Vehicles

According to the International Maritime Organization (IMO), “Maritime Autonomous Surface Ship (MASS)” refers to a ship which, to a varying degree, can operate independent of human interaction. The Maritime Safety Committee (MSC) of IMO is crafting a new, non-mandatory MASS code for adoption as early as 2025. As a kind of small MASS, Unmanned Surface Vehicle (USV) has been developed in order to perform dangerous missions instead of manned vehicle in bad sea weather condition. USV can be controlled remotely or autonomously. USV has more sufficient payloads and longer operation time in sea area than aerial drone. The swarm of USVs are more effective for maritime mission such as intelligence, surveillance and reconnaissance than single USV. In KRISO, the operation system of the swarm of USVs has been developed for illegal ship control support in sea surveillance since 2019. For safe navigation among the swarm of USVs, they should keep the convention on the international regulations for preventing collisions at sea, 1972 (COLREGs). Previously, the swarm autonomous navigation system (SANS) for collision avoidance has been tested in in-land water and actual sea area by using the swarm of KRISO USVs; ARAGON1, ARAGON2, ARAGON3, ARAGON CAT40. ARAGON1 to ARAGON3 have planning hulls with diesel engine and waterjet. They have the length of 8 meters and the displacement of about 3 tons. As a catamaran type USV, ARAGON CAT40 has been developed under the financial support of KOREA Ministry of Science and ICT. It has the length of 11 meters and the displacement of about 10 tons with electric twin motors and sail-drives. Now, we would like to evaluate the performance of autonomous illegal ship chasing of SANS in the actual sea area. Illegal ship chasing algorithm in SANS is a kind of adaptive cruise control and it is implemented by using the control of relative speed and relative position (bow, port, starboard or stern) of the each USV with the illegal ship. Each USV can navigate autonomously without human operation by using SANS. For sea surveillance, radar, Electro-Optical (EO) camera or panorama camera are installed in each USV and all information can be monitored in ground station via LTE datalink. In the actual sea area, field tests are carried out in order to ensure the robustness of swarm operation on the four USVs in the maritime mission of illegal ship control support. Scenarios are tested on the illegal ship chasing such as simultaneous chasing of illegal ship, blocking of detour of illegal ship, interception of retreat of illegal ship and convoy motion on the illegal ship. All of scenarios are tested in the actual sea area by using the swarm of four USVs. In this paper, the main features of SANS and main results of field tests on autonomous illegal ship chasing among the swarm of USVs are described.