Issue 40 Unmanned Systems Technology October/November 2021 ANYbotics ANYmal D l AI systems focus l Aquatic Drones Phoenix 5 l Space vehicles insight l Sky Eye Rapier X-25 l FlyingBasket FB3 l GCS focus l AUVSI Xponential 2021

48 Digest | Aquatic Drones Phoenix 5 The vessel is designed to support multiple sensor packages that can be quickly exchanged in the field to suit different missions. Its 130 mm-diameter moon pool, for example, can support at least six different sensors simultaneously thanks to the space allocated for cabling, the power supplies and the volume in the hull to accommodate the sensor modules. “A flange has to be made for each transducer to attach it to an adapter tube, so that is one integration piece that needs to be tailored to the sensor system the customer wants to install,” Hope explains. For real-time measurement of water conditions, a sound velocity profiler or water quality sensors are deployed using a variable-speed electric winch with 50 m of cable. Aquatic Drones had to develop its own winch for this purpose, as most offshore winches are too big and heavy. Energy and power Among the top-level goals for the energy supply system was flexibility, which was achieved by making it modular so that it can be configured for different scenarios and mission profiles. This flexibility is embodied in different versions of the vehicle. They all use marine lithium-ion batteries supplemented by solar panels on the deck, and the system is sized to provide 2 kW for the payloads, with propulsion power varying between versions. The Electric version has the lowest battery capacity and propulsion power output, suiting it to lower speeds and relatively calm and benign environments. This is essentially the economy model, with the principal cost saving being on the battery pack. The Electric Performance (EP) version has a larger battery capacity as well as a higher power output that enable higher speeds with greater range/endurance. The third version is the Hybrid Performance (HP), which has the same power output as the EP but with the addition of a range-extending diesel generator. That enables 48-hour operations based on a cruise speed of 5 knots and up to 144 hours when sailing at 3 knots, although operating against strong tides will require higher speeds. Transmitting motive power to the water is the job of an inboard direct drive propulsion system selected for light weight, low vibration and low maintenance; it consists of a pair of electric motors driving propellers in ducted nozzles. The propellers and nozzles are optimised for low-speed propulsion to maximise mission endurance, having been selected for optimum efficiency and minimum noise over the boat’s typical survey speed of 5-6 knots. “We can gain some extra thrust from the nozzles around the propellers, but we will be testing to see what the real optimum is,” Hope says. “In our application there are many situations in which we can be in shallow waters, and the nozzles also add some bottom protection for the prop blades.” The propulsion system has redundancy, as does the steering, with an independent electric rudder aft of each nozzle. There are other benefits to electric propulsion, smoothness being equally important for survey missions. “That suits our application because you don’t want to vibrate the multi-beam echo sounder, as that can produce noise or variations in your measurements,” Hope says. The electrical system has a built-in charger that accepts shore power at currents up to 32 A, which means October/November 2021 | Unmanned Systems Technology The operator’s view of the vehicle management display showing waypoints on the harbour map, camera views and essential navigation and health information Like the vehicle itself, the hydrographic survey system can be operated from anywhere with a good internet connection to the cloud