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

50 that a shoreside transformer/charger is not required, and the batteries can be fully charged overnight. For payload support, the system has multiple DC buses supplying 12, 24 and 48 V. “A lot of systems need 24 V, and we have about 1.5 kW of 24 V power and about 1 kW of 12 V power, but these things are all adaptable for each project,” Hope explains. Up to 2 kW of AC power is provided by the vessel’s inverter, power that Hope describes as very stable and smooth. Finally, a small uninterruptible power supply (UPS) is sized to keep the comms and navigation systems running for around an hour after a main power failure, its power being supplemented by solar panels. Batteries, power converters and propulsion motors are housed together in an insulated and air-conditioned compartment. The air-conditioning system, which runs from the AC supply, is a marine unit from Dometic that is in widespread use on pleasure craft. Hope says it was chosen because its seawater-cooled condenser makes it compact for its cooling capacity, and allows the use of batteries, converters and motors that don’t have dedicated cooling systems, although the Phoenix 5’s propshafts are cooled by seawater. Automation Remote and automatic control of all the onboard systems is managed by a PLC from Beckhoff, which gathers data from the motors, battery management system and navigation sensors, and sends out commands to all the effectors that control the vessel. It also allows for dynamic integration of additional systems and sensors as well as remote updates of onboard systems. “That makes it very adaptable compared to a PCB-based design, where you have multiple boards that are custom designed for their applications,” Hope says. “If there is a failure – and custom designs have a greater chance of failure – you have to investigate it and replace a component or the entire board. “With the PLC system, because you can plug modules in and out that are proven, tested and certified in terms of EMC and so on, we can easily add sensors and other systems. So if we need to read an analogue voltage from something, we can put a module on, integrate it into the software and we are done. “We felt that was the best fit for us. PLC systems are not used in small UAVs, for example, because they are rather large and heavy, so custom boards are used, but our vessels are 5 m long, so we can accommodate a PLC system.” Onboard protection The Phoenix 5 is also fitted with automatic systems including fire extinguishers and bilge pumps to handle onboard emergencies. All the hatches are sealed and ventilators are configured to prevent water ingress, while the UPS keeps the comms and navigation systems alive in the event of a failure in the primary power supply. The team regards a fire extinguishing capability as essential. “It’s a very valuable asset, and we have lithium-ion batteries on board,” Hope points out. The automatic system includes canisters from FirePro with a dual redundant activation system and independent thermal and electrical triggers. The thermal triggering system October/November 2021 | Unmanned Systems Technology The autonomous capabilities integrated into the Phoenix 5 were developed on earlier, smaller USVs and proven in a series of technology demonstrations