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95 surroundings appear to change as the ship moves through it. The 25 kg SceneScan emits a 25 mm beam of light from a pulsed laser diode at a 905 nm wavelength and 7.5 kHz frequency. The sensor’s power consumption is a maximum of 130 W, and a single-axis gimbal compensates for wave motion and provides the vertical FoV. Maritime Robotics was at the show to present its autonomous vehicle portfolio, including its newest USV, the Otter. Designed for bathymetric surveys of inland water bodies, the vessel is equipped with a multi-beam echo sounder from Norbit Subsea as standard, and can operate for up to 20 hours at a cruising speed of 2 knots, or 15 hours with the echo sounder ‘pinging’ consistently. “We chose a catamaran design for the USV for stability on the water, and for portability – it can be disassembled and carried by one person,” said Arild Hepsø. “When assembled it weighs about 100 kg with four lithium-polymer batteries and measures 2 m long. We’re also working on Lidar integration to autonomously avoid kayakers and other objects while conducting survey mapping.” GPS and AIS are also used in the company’s navigation and detection systems. A 2.4 GHz data link can connect to the USV from 500 m to 5 km away, or a GSM connection can be used to provide a BVLOS feed. For redundancy, the navigation system uses a ‘majority voting’ set-up between IMUs. The company also showcased its Mariner USV, a 5.85 m polyethylene single-hulled craft. For propulsion it can use either a waterjet thruster powered by a diesel engine for speed, or a stern drive powered by a diesel-electric hybrid system for persistence. “You’re looking at an endurance of either two or 30 days, depending on which powertrain you go with,” commented Joel Pederick. In its speed-focused configuration, the Mariner can achieve maximum speeds of up to 30-plus knots. The system is also built with a moon pool, to allow sensors to be lowered by elevator under the water. ​ Sirenha, an r&d company for marine vehicle hydrodynamics and a subsidiary of French company DCNS, presented its concept for the Remorina USV at the symposium. It is built to demonstrate interception and neutralisation by an unmanned rigid inflatable boat. “We designed the system with modularity to test different hardware such as comms systems,” said Bruno Sourice. “We are working on an algorithm to optimise the transfer of data between the USV and the control centre, alongside software enabling artificial intelligence for situational awareness, decision-making and predictive collision avoidance.” The Remorina measures 8.15 m from bow to stern and 2.7 m at its widest; it has a typical weight of up to 3000 kg and a top speed of up to 38.5 knots. Typical operating ranges for the system are from five to 10 nautical miles. The system’s sensor suite integrates sonar and Lidar for short-range tracking, an EO/IR camera for medium-range detection, and radar, AIS and audio tracking for long-range awareness. Sirenha’s detecting and tracking algorithm is also embedded with the software for automatically monitoring targets at sea. These can include static objects such as buoys, moving objects such as other ships, and environmental factors such as waves and currents. Autonomous Ship Technology Symposium | Show report Unmanned Systems Technology | August/September 2018 Guidance Marine’s SceneScan Lidar measures range and bearing The Otter USV from Maritime Robotics is designed for surveying inland waters