Unmanned Systems Technology 026 I Tecdron TC800-FF I Propellers I USVs I AUVSI 2019 part 1 I Robby Moto UAVE I Singular Aircraft FlyOx I Teledyne SeaRaptor I Simulation & Testing I Ocean Business 2019 report

48 Telecoms AutoNaut, having developed and matured its main 5 m-long USV roughly two years ago (as detailed in UST 12, February/March 2017), has launched a 3.5 m version of the wave-propelled craft, aimed primarily at providing a mobile maritime comms hub. “The advantage of the 3.5 m variant is that it is more straightforward to recover at sea – that can be done with the 5 m too but the 3.5 is lighter and has a single-point lift,” says Pete Bromley, managing director at AutoNaut. “Recovery and launch are therefore quicker and safer.” While the 5 m version has more carrying capacity for power and sensors, and therefore more versatility, the 3.5 m craft is designed to be more focused on missions such as comms relay, after AutoNaut’s clients started asking for a more ‘deployable’ long-endurance USV built around a single primary sensor. The 3.5 m AutoNaut’s lack of an engine or propellers for propulsion means acoustic sensors can transmit and receive with minimal interference, and its wave-powered control system enables it to hold station between two points needing it as a relay. Bromley notes, “Station-keeping is sometimes a challenge for renewably powered USVs – be they sail-, wave- or solar-powered – but the AutoNaut can continuously circle a given waypoint within a radius as little as 25 m. We’ve now conducted missions of several weeks in length but there is scope to go for many months at a time.” The AutoNaut 3.5 is currently rated to perform for three months or more, potentially providing comms between two moving points, such as separate scientific research or maritime prospector vessels, or between a moving vessel and a shore base. “Originally, the early prototype and pre-production AutoNauts were in fact all 3 or 3.5 m long,” Bromley says. “We scaled up to 5 m for the first production model because that allowed us to concentrate on ensuring mechanical robustness and providing versatility to early adopters. After much sea-trialling and a wide range of missions with the 5 m craft, we then brought the lessons we learned back into the 3.5.” Such lessons helped to inform the layout of the internal architecture so that the 3.5 m version’s designers could make the best use of the space. And the wave propulsion system was designed to be fundamentally scalable, meaning most of the changes between the two unmanned craft simply involved miniaturisation of the hull and the propulsion system’s architecture. The 3.5 m version integrates 170 W solar panels onto a hull that is built from fibre-epoxy composite, with structural PVC foam sandwiched into the internal structure for additional buoyancy. The PV cells charge two 90 Ah lithium-ion batteries, which supply the 40 kg (or 270 litres) of payload volume the USV can carry, and the standard UHF line-of- sight comms system it comes with. Defence and security The Accession USV is a project funded by the European Regional Development Fund and developed by UK company Unmanned Survey Solutions (USS). The financial backing was awarded through Marine-i, an EU-funded programme for promoting marine technological innovations. The project was given the green light for development in April 2018, and around nine months of design work followed. Like many unmanned vehicles being developed, the vehicle is based around a modular framework, but rather than simply having one or two swappable payload bays, the Accession’s hull is June/July 2019 | Unmanned Systems Technology AutoNaut has unveiled a 3.5 m version of its solar-powered, wave-propelled craft, initially for users seeking a maritime comms relay platform