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48 The system also features a wave- piercing catamaran hull, cited by XOcean as important for providing a stable platform for mounting sensors. Ives says, “The XO-450 is designed to be large enough to carry and power the necessary sensors for commercial ocean data capture, yet small enough to minimise propulsion power consumption for extended-duration operations.” The 4.5 x 2.2 x 2.2 m hull encompasses a sonar post, CTD sensor winch, weather station and mounting areas for a motion reference unit and acoustic Doppler current profiler. The XO-450’s satellite data link uses the Iridium and Inmarsat constellations to provide redundancy for BVLOS comms and telemetry, and to enable each one to compensate for any issues with the other’s latency, stability and speed. “Technological factors that drove the development of the XO-450 included improvements in the performance – and a reduction in the cost – of satellite comms, as well as imaging systems and processing power,” Ives says. Specific improvements in these systems include a reduction in packaging size, weight and power requirements. Ongoing advances in power systems including large lithium-ion batteries, solar arrays and controllers were also critical. Environmental protection In addition to covering more of the ocean, USVs are being used increasingly for duties in urban waters. For example, as part of the Dordrecht Smart City programme, the WasteShark USV from RanMarine has begun a series of tests in the Dutch city’s canals. It collects any waste in its path, in a basket under the centre of the hull, and is designed to carry up to 550 litres of refuse and debris. The tests have two aims – collecting the actual waste, and collecting data on water quality. An onboard module has sensors to measure water temperature, turbidity, pH balance, salinity, depth and levels of dissolved oxygen. The data collected will be measured against the miles of waterways covered and the time of year, including changes that occur into spring and summer. “During the summer in Europe, there are a lot of fluctuations in things like algae and biomass,” explains Richard Hardiman, CEO of RanMarine. “These develop according to the amount of sunlight. That changes the condition of the water – the smell, the oxygenation and so on. “We’ll show the local government how we can keep track of those, and show them exactly what’s in the water.” Past surveys of this kind have used sensor arrays on fixed buoys, rather than moving platforms. By sampling water from canals all over Dordrecht, however, the WasteShark is expected to accrue a more holistic and informative body of data than might be possible with a typical sensor buoy. Data collection is expected to help predict issues such as algal blooms, to encourage preventative measures more efficiently. The Dordrecht tests follow a previous series of tests conducted in Rotterdam to prove the USV’s ability to collect waste (see UST 11, December/January 2017). Hardiman says in those tests it was manually controlled over a 200-300 m range, and performed as hoped. “We’ve now moved up to building our own controller, which uses comms links for heavier data telemetry, so we can operate at up to 5 km and receive data in real time,” he says. These new controls and comms enable June/July 2018 | Unmanned Systems Technology The XO-450 will combine solar cells with a micro diesel generator to power its survey operations (Courtesy of XOcean) In addition to cleaning Dordrecht’s canals, the WasteShark USV will collect data on urban water conditions for long- term treatment planning (Courtesy of RanMarine) Insight | USVs