Uncrewed Systems Technology 049 - April/May 2023

32 riding on top of waves, rather than ploughing through or piercing them. That enables it to navigate through rough sea states and over very short, steep waves while minimising any loss of forward momentum and any severe movement of the central tray. Naturally, the shape and materials can vary between users. Mehlman notes for example that Hypalon hulls have proven more popular among the company’s European customers. The metal parts used in mounting the WAM-V’s thrusters – along with any others likely to be submerged, depending on the use case – are typically made from a 5000-series aluminium. 6061 aluminiumwith a Type III hard anodising coat treatment is used for all the metal components above the waterline, such as the tray and legs, for corrosion protection. “Dr Conti has a particular love of titanium and its mechanical properties, so almost every WAM-V has at least one titanium part,” Mehlman adds. “Our modularity also allows us to try different materials and swap metals or fastening techniques where we can, such as different grades of aluminium within the acceptable series, or doing a weld in place of a rivet, or vice versa. That means we can be flexible with materials so long as we keep the primary concept of the articulating structure on top of the inflatable hulls.” Assembling and disassembling the WAM-V relies mostly on tool-less quick connect/disconnect devices, including the fuel lines and HV and LV connectors, with only a 13 mm box wrench needed for the battery cable. Multiple pins are found at each mounting point (such as for payloads and thrusters) to prevent any section hingeing on a single failure point. “And since the WAM-V 22 is quite large, when the user wants to fold it for transportation, it uses servo actuators so that with the push of a button it folds itself electromechanically, rather than them having to go through a disassembly process,” Gundersen notes. “It can also unfold the same way. Electromechanical locks secure the structure together after unfolding, it then runs a safety check to make sure all the locks are in place, and it detects any resistance to the fold so that if anyone’s finger for example should somehow get in the way, it immediately backs off.” Computing and control systems TheWAM-V’s main computer can be rapidly configured for a wide range of connection pins, both digital and analogue. That is crucial to the USV’s modularity, as it allows any user to fit their preferred electronics, batteries, thrusters and so on. “We use a card-based system, in which we can take an approximation of each end-user’s requirements and I can whip up a circuit card for that, and click it into place. Everything the user could need for a totally new or unusual instrumentation set is then ready,” Mehlman explains. “It’s taken quite a bit more effort to configure our computer network to accept modular additions of new algorithmic blocks as easily as possible. But the card system is easier, and it’s meant for instance that when I wanted to install a new anemometer for wind readings, it took maybe a day to hand- solder a new card to integrate it.” On theWAM-V’s computational limits, Mehlman estimates that around500W is the usual cap on power fromthe battery to the computer systems, and that about 1m 3 of volume is a safe amount of space to set aside. Around500Gbytes of SSD storage comes as standard, with three network ports and an environmental temperature tolerance of up to +70 oC, but again these are not sticking points for theUSV. Just as the computer system is flexible, so is the range of AI functions that can be installed. While object recognition, SLAM and sense & avoid are among those used by the WAM-Vs, smart following has formed most of the intelligent capabilities requested by the USV’s end-users. “That’s for the WAM-V following a April/May 2023 | Uncrewed Systems Technology At 20 knots the WAM-V 22 has a high top speed for a USV, partly as survey speeds requested by users continue to rise