Uncrewed Systems Technology 049 - April/May 2023

Marine Advanced Robotics WAM-V | Dossier ROV, that weight needs to be taken out fromelsewhere, such as the fuel. “If you’re just carrying a light water- quality sonde though, then obviously a lot more fuel can be carried. For instance, the vehicle we had running in Alaska had about 40 gallons [151 litres] of fuel, which was enough for about a day of surveying.” Each outboard on the WAM-V 22 typically integrates a 15 A alternator, and MAR tends to use the one shipped with it, rather than using a new one and potentially introducing a new error. The company has also installed marine generator sets onto the WAM-V 16 to get more range when needed, adding to the modularity of the powertrains. In addition to the fuel serving as the primary energy storage, one battery pack provides the regulated power output needed by the payloads and other electronics. This has included instances of charging Planck’s Shearwater UAV while it was sitting on top of the WAM-V, using conductive or inductive receptacles. A separate battery is used for starting the engines. Although the BMS varies in its combination of in-house and third-party designs and programming aspects, a consistent role for it is to isolate those two packs and their respective buses from each other. “One important reason for this BMS role in each WAM-V is ensuring the safety of the alternator – we don’t want to have to be constantly spinning the alternators, as that will lead to damage,” Mehlman says. “We might also be using different cell chemistries in each battery. The starter battery is almost always going to be some kind of lead-acid device, or it can be larger for more back-up energy if needed. “Meanwhile, the payload battery will often be a lithium-ion system, or even a nickel-metal system depending on what’s necessary or available. The BMS therefore manages each pack separately and isolates them to prevent mismanagement.” Payload integration At maximum loading, the WAM-V 22 can carry 270 kg of payload and 333 litres of fuel. If a user were to add an extra 50 kg of fuel then the payload would need to be capped at 220 kg to maintain stable flotation. As noted, the payload mass can be distributed about the tray, hulls and ski as needed, while the RSM comes in different versions to account for the sensors and their sizes that end-users might want to use. For instance, multi-beam sonar arms have been installed, and these are mounted on the back of the tray along with a linear actuator, with the sonar integrated at the front. This results in a downwards-rotating motion of the arm, from a tucked position against the underside of the tray, to sticking vertically downwards with the sonar until sufficiently submerged for producing clear survey data. With other payloads, such as a glider or sub-bottom profiler, a mechanical linkage couples the system to the tray until disengaged, at which point the subsystem drops into the water. Telescopic arms have also been used, along with other systems as appropriate. Also, through the dedicated battery, payload power can be remotely shut off or reactivated, to conserve power or if a sonar, Lidar or similar fails and needs a hard reset. “Failures tend to be rarer with our USV design than in a typical monohull aluminium vessel,” Mehlman adds. “We’re not hitting the waves anywhere near as hard, which translates all the way down the stack. Payloads and other customer equipment is very well protected, both by that and by the WAM-V having a lot of integration space for sensors to be installed somewhere far fromwhere waves will be striking.” Future plans In addition to manufacturing and selling the WAM-V 8, 16 and 22, MAR has been developing its Robotics-as-a-Service (RaaS) business model, particularly for customers who need USVs on a less predictable, ad hoc basis. So, as well as sellingWAM-Vs, it anticipates increasingly leasing or operating units on behalf of ocean data customers. Further use cases of simultaneous UAV and UUV deployments from the USV will also be explored, with illegal fishing missions having showcased the benefit of having simultaneous aquatic and aerial assets working together for persistent maritime security awareness as much as repeatable marine infrastructure inspections. 37 Uncrewed Systems Technology | April/May 2023 WAM-V 22 Length: 7 m Beam: 3.66 m Draft: 0.56 m Speed: Up to 20 knots Weight: 1134 kg (without fuel, oil or payload) Endurance: Up to 72 hours at 8 knots Propulsion: 2 x 20/30 bhp, gasoline Payload: 270 kg Fuel capacity: 151 litres Some key suppliers GNSS: Applanix GNSS: VectorNav Actuators: Lenco Electric thrusters : BlueROV Electric thrusters: Torqeedo Gasoline thrusters: Honda Gasoline thrusters: Suzuki Radios: Kongsberg Maritime Radios: Microhard Radios: Rajant Radios: Silvus Satcom: Starlink Maritime Rigid inflatable hull sections: Wing Inflatables Specifications