Unmanned Systems Technology 042 | Mayflower Autonomous Ship | Embedded Computing | ElevonX Sierra VTOL | UUVs insight | Flygas Engineering GAS418S | Ocean Business 2021 report | Electric motors | Priva Kompano

40 Thompson adds, “Solara were extremely helpful in figuring out the optimal layout and how much solar we could fit to maximise our energy intake while still having a workable, accessible deck.” That energy goes to the (LiFePO 4 ) battery packs below deck. They are arranged as eight modules (in four strings of two), each weighing about 60 kg and measuring 600 x 350 x 200 mm, with up to 60 kWh of energy storage in total. The batteries are also intermittently charged (when energy levels drop to a preset value such as 20% or 40%) by the diesel generator. This is supplied by Fischer Panda, and is built around a Kubota four-stroke diesel engine and reprogrammed by the Mayflower team to run on Piktronik controllers and biodiesel. Filling ports and fluid depth sensors for the vessel’s three fuel tanks are installed and accessible from the top deck. “Naturally it will run more often the more drag and speed you have, but we’re also going to preset it to run more sparingly if marine wildlife is detected – we don’t want to disrupt their activities or cause them any stress with engine noise,” Phaneuf says, adding that the AI Captain can control when the generator is running according to operating requirements. When docked, shore power can be used to replenish the battery via an AC charge port located between the aft access hatch and solar panels. Two 20 kW electric motors are installed for redundancy (one is integrated as a direct drive power source, the other acts on the propshaft via a belt) and drive a single propeller. The propeller comes from Teignbridge, and is custom- designed to absorb the full 40 kW of the e-motors without cavitation, although the Mayflower rarely produces more than 12 kW of total thrust. The overall propulsion system is a Vetus modular bow thruster, operated via CAN bus and Piktronik controllers. The rudder meanwhile is controlled by an electro-hydraulic actuator, with a back-up pump system for redundancy. Comms and remote monitoring The Mayflower is naturally agnostic as to which comms systems can be installed, and no data links are needed for operations. As Scott notes, “All the computing capability is resident on the vehicle itself, which is why we call it the ‘ultimate edge device’.” That said, the mast typically features at least one pair of antennas for wi-fi, 4G, Iridium or other satcom systems, with part of the AI and control algorithms dedicated to determining which medium to use and when, depending on bandwidth, range, power, availability and signal strength. “When determining how best to February/March 2022 | Unmanned Systems Technology Lithium iron phosphate battery packs store the energy incoming from the solar panels… …as well as the energy supplied by the on-board biodiesel generator, a slightly modified Fischer Panda system built around a Kubota four-stroke