Crisscrossing the world’s oceans is a hidden fleet of AUVs performing covert tasks. This shadowy surveillance world was briefly exposed by China’s seizure of a USN AUV operating in the South China Sea on 15 December 2016.
The survey ship USNS Bowditch had been operating the Littoral Battlespace Sensing-Glider (LBS-G), built by Teledyne Marine, in international waters west of the Philippines on ‘routine operations’. Before the glider could be recovered, a small boat from a People’s Liberation Army Navy (PLAN) Type 922 ship swooped in to pick it up. China returned it several days later, claiming its act was to ensure ‘safe navigation of passing ships’.
China is paranoid about US and foreign naval vessels or aircraft operating off its coast. Interestingly, since 2016, Beijing has issued annual awards for fishermen who capture foreign AUVs, even if in international waters. In 2018, nine such devices were recovered.
The PLAN unleashed a surprise of its own when it displayed two identical large-displacement UUVs (LDUUVs) in its 1 October 2019 parade in Beijing. Labelled HSU001, this vessel reflects China’s prioritisation of unmanned technologies. There is no indication of how the PLAN will use HSU001, but it has a nose-mounted sonar and mast-mounted sensor. It could potentially be carried on the deck of a Chinese nuclear submarine and then deployed out in front to identify enemy submarines or to perform ISR missions.
Another possibility, perhaps a complementary one, is that the LDUUV can deploy smaller AUVs of its own, or release sensors or mines. What could be mounting points for external stores are on the flanks. Twin screw-back propellers are located at HSU001’s rear, while vertical and horizontal thrusters are fore and aft, suggesting it is designed for slow-speed cruising near the surface.
Information on the PLAN’s use of AUVs is limited, and the crossover between research and military use is blurry. For instance, in mid-December 2019, the Chinese Ministry of Natural Resources released 12 Sea Wing (Haiyi) underwater gliders from a survey ship in the eastern Indian Ocean, later recovering them in February 2020. The Sea Wing is the Chinese equivalent of the US LBS-G.
Such gliders gather oceanographic data such as seawater temperature, salinity, turbidity, chlorophyll and oxygen levels. This information is pure gold for submarines and ASW; navies are therefore particularly interested in AUVs that can discreetly collect such data. Unmanned platforms also have an advantage whereby no lives are lost and a degree of deniability is invoked if they are captured.
The Tianjin University-designed Sea Wing has a 1,500km range and 60-day endurance. It employs variable-buoyancy propulsion, where a balloon-like device filled with pressurised oil is inflated/deflated. This propulsion method permits high endurance but low speeds. Data can be transmitted back to a mother ship or land-based command centre via satellite.
This article provides a snapshot of some further AUVs available on the international market for ISR; rapid environmental assessment; and intelligence, preparation of the operational environment (IPOE). With only 19% of the global seafloor sufficiently surveyed, there is plenty of opportunity for ongoing underwater ISR. AUVs have either flooded or pressure hulls, with trade-offs between buoyancy and volume coming down to the design ethos of an individual vehicle. A torpedo shape is the most common, although such a profile is ill-suited to hovering.
Last year, Teledyne Marine announced the USN had awarded it a $5.4 million contract for more LBS-Gs, with options worth $22.2 million available out to December 2024. Teledyne received its first LBS-G full-rate production contract from the USN in 2011, and dozens are in service.
As well as the LBS-G, Teledyne makes the Gavia. The Polish Navy recently announced it was purchasing two additional Gavias for MCM tasks, adding to a 2014 order for a single system.
Richard Mills, VP of marine robotics sales at Kongsberg Maritime, described the Hugin family, which has variants available with 3,000m, 4,500m or 6,000m depth ratings. Customers include Finland, India, Indonesia, Norway and Peru. The 6.6m-long, 2.2t Hugin Superior has the highest spec, and payloads include a Kongsberg HISAS 1032 long-range synthetic aperture sonar, EM2040 MkII multi-beam echo sounder and EdgeTech sub-bottom profiler.
Sensor fits for subsurface ISR and MCM missions are essentially the same, with a typical AUV having a side-scan sonar, multi-beam echo sounder, camera and sub-bottom profiler. Synthetic aperture sonars have become a de facto standard for navies too. Mills believes MCM today constitutes perhaps only 30-40% of AUV utilisation, with things like ISR and IPOE being primary roles.
Development of payload sensors will continue, but perhaps more critical is being able to use their data autonomously. AUVs today have navigational autonomy, but reactive autonomy (the ability to react to the environment and what the craft sees) is where the next leaps forward will occur, Mills predicted. An example is detecting a target and photographing it without operator input. One challenge is how to truncate the data processing procedure so that it is actionable even before the AUV returns.
Hugins typically use lithium polymer pressure-compensated batteries, although advances in this area have plateaued somewhat, especially compared to the automotive industry. Mills said the fuel cell is potentially making a comeback, and hydrogen-oxygen cells are suitable for LDUUVs, for example. However, navies will be reluctant to recharge hydrogen batteries aboard surface vessels; low-output saltwater batteries are another future possibility.
Mills noted that today about two-thirds of Kongsberg AUVs are destined for defence forces, though navies typically divulge little about how they use them. He believes psychology has played a part in the slower uptake of AUVs compared to UAVs, since trust is harder to muster when you cannot see your craft deep underwater. Nonetheless, confidence has grown as technology matures, and generational attitudes among users have developed too. Mills also observed that utilising unmanned systems is now being driven from the top rungs of navies, whereas in the past it was often the lower tiers pushing for it.
Huntington Ingalls Industries (HII) acquired Hydroid from Kongsberg in March, and its AUVs are used in more than 30 nations, primarily by navies. Its main ISR product is the Remus Technology Platform. Hydroid demonstrated the launch of a UAV from a Remus 600 in 2017, and more recently delivered a man-portable Remus 300, rated for 300m depths, to the USN for test and evaluation.
Tom Reynolds, senior director of business development at HII Technical Solutions, told Shephard: ‘Because [Remus] is scalable, advancements can be easily integrated across all AUV classes, from small to extra-large classes. The core technology that the AUV is built on is the most important piece – the hull and depth rating can be scaled around that. AUV technology will continue to advance in the future, and we hope to see industry breakthroughs of safe, longer-endurance energy options; improved communication data rates; and advanced automatic target recognition algorithms.’
Moving on, Hydroid’s Seaglider uses buoyancy to move through the water column and, with no externally moving parts, such craft are effectively silent. Reynolds explained: ‘Their typical operational mode leaves them submerged more than 90% of the time, so they are an ideal platform for ISR missions.’
As part of its Iver family, L3Harris Technologies unveiled the Iver4 580 in June. Suitable for survey, multi-domain ISR, ASW, seabed warfare and mine warfare missions, this variant that is 2.08m long and 147mm in diameter can operate in water 200m deep.
A spokesperson noted: ‘AUVs have become increasingly reliable with greater navigation accuracy and ease of operational use. As the AUV market grows, mission types and scale are increasing. L3Harris continues to invest in modular approaches that allow payload and energy sections to be swapped in the field without special tools and to scale these innovations across different AUV size classes. Alternative energy solutions that increase safety and minimise logistics through ease of handling and transport, while not sacrificing endurance, are being matured.’
Furthermore, ‘in partnership with our military customers, L3Harris is evolving data processing, storage and offload methodologies. In order to fully utilise these gains, AUV security has to increase, and L3Harris is utilising experience across various programmes, including F-35 and XLUUV [extra-large UUV], to lead this space,’ the spokesperson explained.
General Dynamics Mission Systems acquired Bluefin Robotics. The lightweight Bluefin-9 weighs 70kg and is 2.48m long, meaning it can be manhandled from a RIB. It has an 8h endurance. The Bluefin-12 weighs 250kg, is 4.83m long and has an endurance of 24h at 3kt. Finally, the 750kg Bluefin-21 is 4.9m long and can dive to 4,500m. All three are contributing to USN programmes of record. Elsewhere, the Royal Australian Navy is currently receiving Bluefin-9s and Bluefin-12s under Project Sea 1778 for MCM tasks.
Paul Dalton, Bluefin’s director of combat and autonomous systems, amplified the challenges for AUVs: ‘Compared to air, ground and surface-based unmanned systems, operating undersea presents unique challenges for navigation, power, communications and autonomy.’
For example, AUVs transit long distances with periodic or limited GPS data. Bluefins thus have ‘dynamically tuned internal navigation solutions coupling real-time INS and Doppler velocity log data to enable hyper-accurate and reliable navigation’. For energy, the company is ‘continually evaluating power solutions that are safe and reliable throughout the undersea domain,’ Dalton noted.
He also said the company is ‘making strides through acoustic communications data compression’, as well as AI and machine learning to enable AUVs to autonomously process data on board and transmit select data sets.
What about future trends? Dalton shared: ‘AUVs will continue to expand their role in naval operations and in the provision of new data that commanders need to integrate into their decision-making process. AUVs to date provide valuable data points informing situational awareness, ie environmental, hydrographic, bathymetric and localisation data for objects of interest. The delivery of this data from deployed and over-the-horizon AUVs will continue to be integrated into naval operations to enable a more flexible distributed maritime operation.’
Atlas Elektronik is known for the SeaCat AUV family, ranging from 2.5-3.5m long. More than 3,000 Atlas AUVs have been sold to date, and the company’s SwapHead technology allows payloads to be reconfigured.
Atlas’s parent company ThyssenKrupp Marine Systems (TKMS) revealed: ‘To expand the reach of our unmanned systems, and expand the range for covert operations in confined waters, TKMS is working on the integration of AUVs with submarines. This will give the AUVs the “longer legs” of a submarine and provide the submarine with additional sensors and tactical flexibility. The company’s future XLUUVs go one step further and will feature ISR sensors with capabilities similar to submarines and have the endurance for standalone operations.’
One interesting ongoing TKMS programme is the Modifiable Underwater Mothership (MUM). Funded by Germany’s Federal Ministry for Economic Affairs and Energy, the commercial project kicked off in 2017. The MUM represents a modular underwater platform for tasks such as transporting and deploying payloads for the offshore oil, gas and wind markets, or exploring challenging areas.
The MUM uses 3,000kWh-storage-capacity fuel cells, perhaps supported by lithium-ion batteries. In the programme’s forthcoming second phase, a large-scale demonstrator 25m long, 4m wide and 3m high could be operable by 2024. Despite it being a civil programme now, TKMS imagery shows scout, minelaying and hunter-killer MUM variants are anticipated. The vessel could carry four heavyweight torpedoes, nine naval mines or a 30+m towed array, for instance.
Addressing future trends, TKMS told Shephard: ‘Military AUVs will outgrow the niche of their current size and missions. In the future, midget and smaller submarines will be replaced by capable AUVs for sea denial, mine warfare, battlespace preparation and other missions. A lot of the existing software and autonomy will be transferred to larger and more capable platforms.’
The representative continued: ‘TKMS will use the best ideas from more than 160 submarines built since the 1960s, and decades of AUV prototyping, to come up with new models. These differentiate themselves from competitors’ vehicles with superior underwater endurance while fielding heavy and energy-hungry payloads.’
LDUUVs can perform dull and dangerous missions such as deploying sensors, laying mines or providing fuel or battery power to other AUVs. One advantage is that they cost a fraction of a manned submarine.
In 2019, the USN awarded Boeing a $274 million contract for five Orca LDUUVs, to be delivered by 2022. The 15.5m-long Orca builds on Boeing’s experience with the Echo Voyager commercial prototype. Deploying weapons on an AUV is controversial, however, so policy questions would have to be resolved first.
Non-lethal payloads are also possible, such as jammers, EO/IR dazzlers, microwaves and UAVs. The USN is exploring how to use AUVs to protect nuclear-powered ballistic missile submarines, for example. The navy’s first AUV squadron, UUVRON-1 (established in 2017), is exploring this concept.
The UK is also evaluating extra-large AUVs, and in March the MoD confirmed the RN would receive an approximately 9m-long Manta from Plymouth-based MSubs. This $3 million award followed a mid-2019 competition by the Defence Science and Technology Laboratory (Dstl) for a no-frills vessel that could perform ISR, underwater data gathering, payload delivery/recovery and remote automated sense-and-warn missions. The Manta demonstrator could lead to an operational RN XLUUV within five to ten years.
Dstl listed three covert mission scenarios in which such a craft could be utilised: monitoring traffic in a maritime area for up to three months, perhaps by lying on the seafloor and releasing a tethered sensor to periscope depth; as part of an anti-submarine barrier in a checkpoint or patrol pattern; and deploying a payload onto the seabed and later recovering it.
Hanwha Systems in South Korea is developing a large ASWUUV with a 30-day endurance, with trials supposed to start this year. Details about Russian ambitions meanwhile are limited, but the Project 7P22 Garmoniya-Guide is a Rubin design of unconfirmed existence. Russia has also publicised plans for the Poseidon intercontinental nuclear-armed and nuclear-powered autonomous torpedo, as well as the torpedo-armed Cephalopod XLUUV that was funded from 2015 onwards.
One interesting area of R&D is biomimetics, the copying of nature. AUVs that can mimic a sea creature’s method of movement can be more efficient, harder to detect and therefore more survivable. Examples already exist, including: the European Defence Agency’s Sabuvis II; the USN’s rapid-prototyping tuna-like GhostSwimmer; Australia-based DefendTex has the Sea Hunting Autonomous Reconnaissance Drone that resembles a squid; Boston Engineering’s BIOSwimmer; and several Chinese craft resembling sharks or mantas.
Kongsberg has invested in Norwegian entity Eelume, which makes an eponymous sea snake-like AUV. The 200mm-diameter vehicle can change its shape to access constricted spaces, and it can be launched from other underwater platforms. ‘There are obvious applications for a vehicle of this type in the defence world,’ Mills stated.