Uncrewed Systems Technology 049 - April/May 2023

34 Dossier | Marine Advanced Robotics WAM-V huge issue for how we work,” Mehlman says. “We can’t afford lengthy design lead times or supply chains with our connector or harness specs. “Most of our LV systems are standardised M12 circular connectors, as they’re very easy to obtain from various sources, and naturally we like wet-mateable systems, but those suffer from supply chain difficulties, so we often avoid them.” The HV connection systems are highly dependent on exact voltages, but all of them are IP68-rated as a hard requirement for approval, to ensure full protection against saltwater ingress. And for both the LV and HV networks, materials in cable jackets and plugs are also selected to ensure survivability against UV light, which inherently breaks down polymers over time. That is especially concerning in the marine environment, as UV rays come as a reflection from the water as well as directly from the Sun. Comms and interoperability The flexibility of the WAM-V’s engineering philosophy is such that several different solutions have been used as the primary radio for vehicle and payload data transmission. These include Kongsberg Maritime’s MBR (Maritime Broadband Radio) as well as radios from Microhard, Silvus and Rajant. MAR does not want to be limited to a single system so long as customer requests continue to be so varied. In addition to running over satellite and cellular networks, it is also now possible to use Starlink Maritime for over-the-horizon command and control. At the time of writing, MAR was demonstrating the control of a WAM-V using Starlink for the US Navy. A secondary radio for remotely operated functions is typically installed alongside the primary radio for tasks such as control hand-off from one operator to another, in ship-to-shore mission patterns or other arrangements. A wide array of antennas have been integrated and used on the comms mast on the central tray, including fixed omnidirectional systems and gimballed directional antennas. A critical objective of the comms mast’s design (whether arched or pole- shaped), as well its antennas, is sufficient height. As the WAM-Vs and their GCSs (on crewed vessels or in harbour offices) can become separated by considerable distances during their missions, it is not impossible that the Earth’s curvature will eventually come between the line-of sight RF links needed for connecting the USVs as well as any crewed or uncrewed assets they are teamed with. “Although the WAM-V’s height is useful for maintaining that link, we consult with experts at the radio vendors, as well as the GNSS vendors, to work through any issues we might get with our antennas,” Mehlman says. “As a result, our ideal network configuration is maintained in a way that any vehicle in the swarm persistently lets every other asset know where it is, not just all the uncrewed vehicles connected over our radio network but also any person with a connected GCS or similar portal. “That includes AIS information if a user has elected to include an AIS transponder in their USV. To be honest though, we don’t consider an AIS data point on the navigational chart to be as reliable as one inside our network, because you’re relying on the AIS operator on that other vessel to have mounted their antenna correctly. “But we do recommend our users have us integrate AIS so they’re putting out that information for third parties and for general maritime safety.” One or two industry-standard ruggedised laptops are generally provided with a WAM-V order, which in turn are installed in crates where extra saltwater and UV protection is needed, such as when the USVs are likely to be operated from a beach or a small April/May 2023 | Uncrewed Systems Technology The pontoons beneath the ball joints are typically made from a Nylon fabric, with a polyurethane exterior and a UV-resistant coating