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48 extended in the New Generation 6000.” The overall larger size of the New Generation AUV – from 3.96 m to potentially as long as 7 m, depending on the modules installed – will also require technical upgrades to the Remus Launch And Recovery System (LARS). This lowers the AUV into the water, tail first, typically as the launch vessel is moving at 1-2 knots. Integrating rotator heads and turntables will be among the modifications to the LARS, which will also be modified to enable launches from the port or starboard sides of the Japanese vessels rather than just the aft, as at present. The updates will also increase the 6000’s weight in air from 862 kg to (potentially) almost 1900 kg. “We’ve also developed more sophisticated underwater navigation systems thanks to shared technology from our parent company Kongsberg, allowing more precision,” Lester adds. “And our integration of a dedicated payload processor means more accurate geo-tagging and timestamping throughout our seabed maps. Metal sulphides tend to be concentrated in very small areas, so UUV navigation systems need to map really precisely where those deposits are.” Hydrographic survey A more accurate navigation system is particularly helpful to AUVs conducting hydrographic surveys, and is a key part of the new Hugin Superior AUV from Kongsberg Maritime, as well as on the New Generation Remus 6000. “We’ve implemented something we call ‘micro-navigation’ processing,” says Richard Mills, director of marine robotics sales at Kongsberg Maritime. “The Hugin integrates an IMU, a doppler velocity log, a depth sensor and other external tools such as our HiPAP [high precision acoustic positioning] SBL or USBL. We take all the raw data inputs from those, and process it on the AUV mid-mission in our embedded NavP navigation software. “We would then tend to process that post-mission in our NavLAB software, which then reprocesses every update forwards and backwards. In-mission, that capability was accurate to about 0.08% of distance travelled in a straight line.” The micro-navigation processing, which was developed in partnership with FFI (Norway’s defence research establishment), had previously only been used in post-processing. Installing it on the new, larger AUV means the need for external updates from the operator’s ship and acoustic transducer is reduced, cutting operating costs. This is also expected to improve accuracy from 0.08% to 0.04% of distance travelled (and possibly further). “Wide-area bathymetry, marine archaeology, large-area surveys and specialist defence applications are the primary niches we’re targeting with the Hugin Superior,” says Mills. “That is purely because of the area coverage and image resolution we can now generate.” To that end, the Hugin Superior is designed to use Kongsberg’s HISAS (high resolution interferometric synthetic aperture sonar) 1032 dual receiver, which is designed for use over wide areas. If the Superior travels at about 2.5 knots, it generates a 1000 m swathe (500 m port and starboard) of seabed imagery and bathymetry, with 5 x 5 cm image resolution and at least 20 x 20 cm bathymetry across this range. “If we compare that to most UUV bathymetry out there now, most of what you can get will generate 50 x 50 cm bathymetry at best, at the 500 m range,” Mills says. “The Hugin AUV will continue performing the kinds of missions it does, but the Hugin Superior is a fixed product aimed specifically at heavy-duty surveys.” The nature of acoustic survey is such that data quality tends to degrade over range. With the HISAS, the Hugin Superior can cover effectively double the area of the Hugin, without losing data quality. The latter is too small to carry this payload, however, and is therefore limited to using the single- receiver variant of the HISAS 1032. The standard Hugin comes in three different depth ratings down to 6000 m, each model having a different diameter. The 3000 m and 4500 m variants are 75 cm across, while the 6000 m AUV is 87.5 cm wide to house the extra batteries needed for deeper dives. As for length, the typical three-battery, 3000 m Hugin AUV is about 5.2 m long, but at 6000 m depth the density of the syntactic foam changes, so to achieve more buoyancy the length of the hull is extended to 6.2 m. February/March 2019 | Unmanned Systems Technology Insight | UUVs The new Hugin Superior AUV has been designed with reduced modularity but increased size in order to survey twice the area of the original Hugin system (Courtesy of Kongsberg Maritime)