99 sparse antenna for detecting submarines below the waves. “By building our AUVs and forming swarms of ULF-detecting underwater nodes with them, we’ve already created antennas as large as 400 m by 100 m, and in terms of the laws of physics, there’s nothing stopping us making antennas of maybe dozens of kilometres in size,” says Brizard, who previously served as a CTO across several Thales Group companies, particularly in its underwater defence solutions. ASW on such a scale has not been achieved before, nor attempted with micro-AUVs. Historically, the biggest passive antennas for submarine detection have been towed arrays, consisting of singular wires of a few kilometres long (although certain geophysics applications have made use of towed arrays up to 10 km long). ASW commanders, however, have criticised towed arrays for producing very ambiguous data, and the cables comprising most of their length are extremely vulnerable to being damaged or cut off. “A mechanical antenna would have similar structural weakness in that damage to one part of it could easily render the whole thing inoperable, but a swarm has no structure,” Brizard says. “We autonomously and accurately maintain a formation of small AUVs in the water, [with] that formation ensuring the effective and precise functioning of the antenna, and thus the detection of submarines and anything else radiating or emitting ULF signals below the waves.” The road to Proteus Arkeocean was co-founded in 2009, by Brizard and his daughter, Tamara, with the latter serving as managing director until 2023, when she transitioned to a new role as president of Keo Robotics, partner company to Arkeocean, on some key technical developments. Until 2019, Arkeocean focused on developing subsea technologies for divers and other aquatic applications, but during that year it joined Aramco’s SpiceRack programme, aimed at using an AUV swarm to perform seismic surveys at 30-40% of the cost of usual approaches. As a subcontractor, Arkeocean was tasked with providing and integrating the C2 (command and control) systems, including acoustic devices for the AUVs (built by another partner), and testing them off the coast of France. This not only brought great tangible experience to the company in engineering high-end swarming AUVs, but also alerted them to the impact that such swarms could have across energy, defence, marine research and elsewhere. So, Arkeocean began working on swarming micro-AUVs of its own, and it started getting contracts for trials and models, including some for the Direction Générale de l’Armement (DGA), the French defence procurement agency, as well as involvement in the French Navy Orion exercise in 2023, which garnered notable recognition. Inca and Maya Through these projects, Arkeocean has developed a few modes of swarm applications, with its Proteus solution being potentially the most comprehensive and complete approach to ASW. Proteus is a swarm operation using multiple units of micro-AUVs, specifically Arkeocean’s Inca and Maya vehicles. The exact number scales with the size of the sparse antenna and the swath of ASW coverage desired, and micro-AUV design plays a distinctly different role in the Proteus operating model, as Brizard explained. Inca and Maya are designed to hover, station-keep and loiter, with minimal operating costs to form a cost-effective, persistent passive antenna. Both AUVs look distinctly different from the Arkeocean’s Inca & Maya anti-sub warfare UUVs | In operation Uncrewed Systems Technology | April/May 2024 Each Inca (left) serves as a node in the subsea sparse antenna, and each Maya (right) serves as a data mule for its corresponding Inca and also as a localisation sensor for the swarm
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