Uncrewed Systems Technology 049 - April/May 2023

30 Dossier | Marine Advanced Robotics WAM-V WAM-V can carry – if a UAV is present as part of the swarm then the user will sometimes choose to have the UAV act as a comms bridge between it and the operator, given its greater altitude and visibility relative to any surface vessel. “In addition to the WAM-V being able to carry more radio power than the UAV, the fact that it can carry more computing power means we can outsource some edge computing and hence AI capability to the surface vessel,” he adds. The USVs are also being developed for crewed-uncrewed operations as autonomous force multipliers. In 2019 for instance, two WAM-V 16s were teamed with a crewed vessel for a hydrographic survey project with the US National Oceanic & Atmospheric Administration in the Great Lakes. The uncrewed systems integrated multi-beam sonars, and the crewed ship carried a networked GCS portal so that all the data (from the USVs and the crewed ship) was acquired and presented in a single UI in real time. “That hadn’t really been done before,” Gundersen notes. “All the vessels were contributing to a single map simultaneously, which meant they knew whether there were gaps or overlaps in the parts of the lakes they were mapping. That’s something you don’t usually find out until after returning to shore for post-processing.” Mehlman adds, “In hydrographic mapping, a lot of the time you either get gaps in your data, meaning you have to go back out and essentially do it again, or you get something like 50% overlap in survey paths, which means you’re not being fuel- efficient. So being able to optimise that in real time – and autonomously – makes a huge difference.” More recently, in 2022, similar missions have been performed around Alaska, including repeated launches & recoveries of a WAM-V 22 from a 115 ft vessel. “On some days around Alaska we were surveying at 8 knots,” Mehlman notes. “That’s faster than usual for hydrographic surveys, but crewed- uncrewed teaming is really pushing demands for speed in our USVs. The more area we can map per launch, the better, and in our experience if you can’t keep up with the crewed vessel, it deters its captain from using your USV again.” WAM-V architecture The largest and hencemost visually noticeable parts of theWAM-V are its inflatable hulls (or pontoons) at the bottom, either side of the superstructure, which provide flotation and some wave absorption. Above those are the suspension parts and the ski structure that leads up to the front and rear arches. These support the central payload tray, which also supports the enclosures for autonomy, controls and navigation, as well as space for a UAV platformand UUVwinch. “Beneath that tray, we can talk about having a moon pool, although really, the entire WAM-V is a moon pool, given the space between the inflatable hulls,” Mehlman says. “There we can install sonars, ROVs, towfish, gliders, all sorts, and in so many different configurations. But we generally put them in and out of the water during missions using our retractable sensor mount [RSM].” Also on top of the tray is a comms mast, which can be configured as an arch or pole, while behind each pontoon is a motor pod. These are interchangeable to cater for different missions and users who might want different speeds, power, torque, noise, carbon emissions and drafts; various outboards, waterjets and other boat engines have been used. “Also, our rudders can be operated in a conventional catamaran style or in differential, tank-type steering,” Mehlman says. “Our control system can do a lot in autonomous mode to decide the best way of steering the WAM-V in different conditions, particularly to optimise the turning radius at different speeds.” Inflatable and metal structures The two pontoons are usually made from a Nylon fabric with a polyurethane exterior and a UV-resistant coating. “That’s all done by a company calledWing Inflatables that we’ve been working with since the Proteus days,” Gundersen says. “The Proteus’ inflatables had six individual chambers, three of which contained a 300 gallon fuel bladder. That allowed a lot of fuel to be securely contained in a pressurised hull, and by using the air pressure in the hulls you could smoothly transfer fuel back to the day tank [a dedicated tank typically sitting between a bulk storage tank and an engine, into which fuel is pumped or gravity fed for consumption by the engine], without needing a dedicated fuel pump.” The geometry of each pontoon is intended to lend the WAM-V towards April/May 2023 | Uncrewed Systems Technology Swarming and a networked GCS allowmultiple WAM-Vs to be used to contribute to a single map simultaneously