Unmanned Systems Technology 001 | UAV Factory Penguin C | Real-time operating systems | Hirth S1218 two-stroke twin | Base stations | ASV C-Enduro | Composites | Datacomms

55 The ASV C-Enduro | Dossier bandwidth, for example, automatically switching between line-of-sight radio and over-the-horizon satellite comms when required. While a customer can have complete control and monitoring themselves, ASV can provide a control and monitoring service from one of its bases, which are in the UK and the US (Houston and Lafayette) but can easily set up the service in other countries. The C-Enduro accepts a combination of payloads on any given mission. It normally carries a meteorological sensor unit atop its central hoop, where an air quality sensor can also be fitted. The hull, retractable keel and an under-deck payload pod provide capacity for in-water sensors, transducers or a towed array connection. In addition, the C-Enduro can be equipped with a winch to tow (usually submerged) sensor arrays. The winch can be set to automatically lower over a range of 0-300 m depth. Ocean CTD (conductivity, temperature and depth) sensors can be lowered by the winch. Typical keel-mounted sensors include a camera and an ADCP (acoustic doppler current profiler), the latter being a hydro-acoustic sensor, similar to sonar and designed to measure water current velocities at different depths using the Doppler effect of sound waves scattered back from particles in the water column. Data collected by the sensors is logged by the onboard computer and can be transmitted back to the operator in real time. Propulsion system The C-Enduro’s propulsion system incorporates twin traction motors, each of which powers its respective, protected fixed-pitch propeller through a shaft and gear drive developed by ASV. The motors and their respective power electronics were developed by Hyperdrive, along with the diesel engine and its integrated generator, which has its own power electronics. Hyperdrive also developed the battery and the dc electrical supply system. The dc circuitry takes power from the diesel generator, the solar panels and the wind turbine to the battery and/or traction motors, and from the battery to the traction motors. The whole propulsion system is CAN-linked and is run by Hyperdrive’s own control unit (the CAN ECU), under the governance of the ASV vessel controller. The electrics The pair of three-phase electric traction motors are each run by their associated power electronics inverter, which is fed from the dc supply that runs at a voltage of about 44-70 V. The diesel-powered generator uses the same-specification power electronics unit, and each inverter is governed by the CAN ECU. The traction motors are permanent- magnet ac units, from the same family as the generator – in effect they are smaller versions of that unit. They were sized as a compromise between weight and efficiency in the context of the overall vessel, says Hyperdrive’s chief engineer Robin Shaw. Each motor has a maximum output of 1.5 kW (2 bhp) with a combined average consumption of only 100 W over the course of a typical mission. The three electrical machines are all cooled by the ambient air within the respective hull (the IC engine/generator is centrally located in the left-hand hull). Initially, the associated power electronics units were cooled by the IC engine’s fresh-water coolant system, but field tests proved that a simple heat sink was sufficient to keep their temperatures under control, saving weight and complexity. The C-Enduro uses a battery made by Hyperdrive, which is rated at 75 Ah. For packaging reasons it consists of two packs, which the system sees as one battery and which behaves as one unit. This dual-unit approach better fits the C-Enduro’s slim hulls, and the modular approach makes it straightforward to add extra packs, for example in place of the diesel/generator unit. Each pack can supply 2.2 kWh with a nominal voltage of up to 33.6 V. The C-Enduro uses ruggedised versions of the regular battery pack, which can survive salt-water conditions and will not fail in the event of a capsize. Each pack has a resin casing that is Unmanned Systems Technology | November 2014 Internals of the Hyperdrive battery fuel gauge The C-Enduro carries a pair of Hyperdrive battery packs