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70 Insight | UUVs The project was planned and overseen by the UK’s Defence and Security Accelerator (DASA), and formed the first phase of its Uncrewed Underwater Vehicle Testbed – Opportunity to Integrate competition, which is being run jointly with the UK’s Royal Navy and the Defence Science and Technology Laboratory. “Our S201 XLUUV already uses a Sonardyne Sprint-Nav underwater navigation unit and a Sonardyne USBL, so the interoperability of those parts with the Vigilant sonar made integration much easier than if we’d used systems from other companies,” says Matt Troughton, chief engineer at MSubs. “When we were refitting the vehicle for phase one of the competition, we made sure to leave plenty of space for integrating new systems in and around the vehicle. The XLUUV contains runs of 19 in racking for COTS electronics boxes, and while the Vigilant itself isn’t the best shape for fitting inside the S201, for the purposes of this demonstration we integrated it on the front of the XLUUV, and that worked great as a short-term solution. “If we move towards integrating it as a long-term subsystem we’d definitely do some further redesigns to mount it inside the nose. It’s a very long piece that has to sit vertically along with numerous other small components, but we’re quite used to rapid turnarounds of new mechanical arrangements for the defence industry customers we tend to serve.” The S201 was originally created about 16 years ago as a manned submersible for in-the-loop testing and real-time development of underwater autonomy software. It was reconfigured as an XLUUV about 3 years ago, after MSubs received a contract from DASA to trial it as an unmanned vehicle, and it is now a 9 m-long, 2 m-wide, 9 t vehicle. It can operate down to 305 m, with a maximum endurance of 48 hours (on battery energy), and has a top speed when submerged of 12 knots. MSubs also developed an S202 several years ago, which is currently being redesigned for a relaunch later this year. It is expected to have two to three times the range of the S201, along with improvements in several other aspects of its performance. The initial trial lasted just a day (rather than a full week as originally planned) owing to poor weather threatening the safety of the support boat’s crew, although trials continued a few weeks later. Real-time data from the XLUUV was available to the GCS operators for much of the time, with the vehicle operating at or near the surface, although submerged tests of the Vigilant were also performed by sending it through the Hand Deeps reef in the English Channel to see how well it detected rocks there. “We’ll do the same test again around April or May this year, but actually aim it towards where we know the rocks to be, to make sure it can really avoid them,” Troughton adds. Summary UUVs can clearly make a huge difference in our ability to slow and mitigate climate change and its effects on the Earth. From studying the proliferation of harmful microorganisms to mass data gathering for large-scale modelling of oil spills or ocean currents, there is a huge gap in our knowledge of how to fight climate change, but one that UUVs are helping to close. It must be remembered though that for UUVs (and all unmanned systems) to be a net gain for sustainability, their manufacturing, maintenance, repair and operations should also be sustainable. Advances in sense & avoid systems, technologies for renewably replenishing energy underwater, and payloads for improving the value gained from each survey, will undoubtedly go a long way towards reducing the carbon footprint of UUVs and their missions. And as we reported in UST 38 (June/July 2021), biomimetic UUVs such as Aquaai’s Mazu are markedly better than conventional UUV designs for gathering data close to ocean creatures without stressing them or otherwise impacting their health. In the near future, UUVs might also be made from new bio-composite materials or recycled plastics. Beyond that, larger scale projects could make an even bigger difference. Just as plans are mounting to build fleets of UGVs to construct hydrogen mining and automated refuelling facilities for themselves on the Moon, so UUVs might one day use or even build geothermal power stations for renewably recharging themselves on the Earth’s seafloor. As with many matters related to saving our planet, such major investments and ambitions could make a huge difference and potentially save millions of lives. February/March 2022 | Unmanned Systems Technology MSubs’ S201 XLUUV is serving as the test platform for Sonardyne’s Vigilant forward-looking sonar (Courtesy of MSubs)