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A new world of multi-robot ocean exploration

The OECI’s Technology Integration Challenge made major strides in multi-robot operations, on the surface and underwater, unlocking ways to explore our ocean – and far more efficiently. Find out how and the role our acoustics played.

The challenge

Ocean exploration is costly. Operations involving single underwater platforms, such as remotely operated vehicles (ROVs) or autonomous underwater vehicles (AUVs), often take up an entire cruise. Even when multiple underwater robots can be accommodated on a vessel, only one tends to be deployed at any one time, due to the complexity involved in its deployment, operations and recovery. It makes ocean exploration expensive and limits how much science can be conducted on any one cruise. But what if uncrewed surface vessels (USVs) could be used, not just as force multipliers for mapping operations, but as a remote shepherd, coordinating multiple underwater vehicles, they would be able to operate entirely freely from a mother ship.

This was a key objective of the US’ Ocean Exploration Cooperative Institute (OECI) 2022 Technology Integration expedition NA139 on the Exploration Vessel (EV) Nautilus.

Enhancing ocean exploration through the use of remote and autonomous operations is a key objective of the OECI, a partnership between The University of Rhode Island, The Ocean Exploration Trust (OET), The University of Southern Mississippi, the University of New Hampshire (UNH), Woods Hole Oceanographic Institution (WHOI) and primary funding partner National Oceanic and Atmospheric Administration (NOAA) Ocean Exploration.

The expedition brought together OECI partner robots together with OET’s EV Nautilus for a ground-breaking technology demonstration in the Pacific Ocean during May 2022. These were:

Mesbot – WHOI’s mid-water robot that is designed to image and sample plankton layers.

NUI – WHOI’s hybrid ROV-AUV, designed initially to work under ice, that can operate out to about 20km on a fibre optic cable for high data rate data, but can also continue to operate without the fibre link.

DriX – UNH’s 7 m-long USV capable of supporting a variety of payloads such as multibeam echo sounders, acoustic communications and tracking and surface communications.

Their goal was to have all three platforms operating together, sharing information and situational awareness and relaying their information, via the DriX, back to the EV Nautilus, enabling scientists onboard to remotely control subsurface operations up to 20 km away from the ship.

Key to meeting their goal was inter-vehicle communications, tracking and positioning.

The solution

The DriX used a marine broadband radio link to communicate with the RV Nautilus (and our HPT 3000) to track, position and communicate with (including providing navigation data) the Mesobot and NUI as part of our Mini-Ranger 2 Ultra-Short BaseLine USBL system.

The underwater vehicles Mesobot and NUI were fitted with our AvTrak 6 combined tracking, telemetry and control transponders. The EV Nautilus was also fitted with our Ranger 2 Gyro USBL system, which would have also be able to track, position and communicate with the Mesobot and NUI, if this had been required.

Mini-Ranger 2 is our mid-level USBL tracking system that’s also able to support communications with underwater vehicles. It can track up to 10 targets at a time, at ranges of up to 4,000 m (with an extended range option) and, with our Robotics Pack, enables command and control untethered underwater vehicles.

For the OECI team, it was this combination of communications and positioning – acomms and USBL – that offered the broadest possibilities to the mission, from a single system.

AvTrak 6 is our tracking, communications and relocation transceiver. It allows USBL aiding for your AUV from a surface vessel and robust telemetry for AUV to vessel and AUV-to-AUV communications.

Ranger 2’s Gyro USBL comes pre-calibrated, thanks to its perfectly aligned acoustic transceiver and built-in attitude and heading reference sensor (AHRS), so you don’t need to take the measurements otherwise needed to determine the alignment of the ship’s motion sensors to the acoustic transceiver.

This makes it a very a portable system that the OET can use on vessels of opportunity. On the EV Nautilus, it was fitted through the vessel’s moon pool.

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The results

“This was a real first for us,” – Professor Larry Mayer, Director of the Center for Coastal and Ocean Mapping, University of New Hampshire.

Over the course of the 16-day expedition near the island of Oahu, off Hawaii, the team tested and demonstrated operational capabilities. Over 30 dives were performed, totaling 210 hours in the water.

The team established a common control system, based on the robot operating system (ROS) for the vehicles and then set out, each time proving out more and more capabilities.

First, they had DriX track and communicate with Mesobot, using Mini-Ranger 2. Because the DriX has GNSS data at the surface, this meant it could position the Mesobot in the real-world and relay this data back to the RV Nautilus.

Next, they sent commands, via the DriX to Mesobot, from EV Nautilus to open and close its samplers, as well as to move up or down or to the right or left as well as change speed through the water column.

But then the most exciting thing happened, explains Professor Mayer:

“Mesobot is designed to sample layers in the water column. But it doesn’t know where they are. DriX has a sonar (EK-80) that could see those layers. So we could get DriX sonar data back on the ship and in real-time see what’s called the scattering layer of plankton and command the Mesobot to go to that layer to sample it.

“Because Drix is circling above, it can actually see the Mesobot in the layer. This was a whole new world. Normally, Mesobot is sampling blindly. We could now direct it into the layer, know it’s in the layer and see if its entrance causes the layer to scatter. All these were unknowns before.”

The team were then able to repeat these activities with NUI, including using DriX to map the seafloor east of Maui and then relay a mission to NUI for further investigation. In addition, CTD data, as well as snippets of imagery and bathymetry were transmitted acoustically up to the DriX, using Mini-Ranger 2, and then via the radio link back to the Nautilus.

“By the end of the cruise we were able to have both vehicles in the water with the DriX circulating above, communicating with each of the vehicles, giving each other situational awareness, and the mothership, it was off do its own thing. I couldn’t have asked for a more successful cruise,” says Larry.

“We are really opening up a new world of multi-vehicle operations. In the old days, we would schedule a cruise and just use the Mesobot or schedule a cruise and just the NUI or an ROV. Even if they would all fit on one ship at the same time, you only use one at a time, so the $60,000 a day would be clicking away and you’re only doing a single science operation.

“Now we can do 2-3 science operations, the efficiencies are tremendous and it allows us to explore the seafloor, water column and surface all at once.

“The Mini-Ranger 2 system gave us the broadest base of possibilities with having both the acoustic communications and the positioning, USBL and acoustic communications, from the same system and that combined set of capabilities was so important to us.

“The standardization and ease at which we were able to send messages across from our programmers made it easy to use. The cooperativeness and responsiveness of the team at Sonardyne was also really helpful. They didn’t see it as disruption, they saw the possibilities.”

The expedition was funded by NOAA Ocean Exploration via the Ocean Exploration Cooperative Institute.

For more information and to watch other videos from Nautilus, click here.

Bringing special order accuracy to small diameter AUVs

L3Harris has armed its Iver3 AUV with Special Order survey navigation capability – thanks to our Mini-Ranger 2 Ultra-Short BaseLine (USBL) system and AvTrak 6. Find out how – and how it will help cut offshore wind farm survey costs.

The challenge

Demand for underwater surveys in coastal waters as part of the offshore wind life cycle is at an all-time high. There’s little sign of that demand falling, thanks to a global shift to renewable energy. But surveys come at a cost.

To keep costs down, surveyors are looking at innovative ways to survey more seabed more efficiently using smaller AUVs that reduce operational costs by requiring smaller vessels and fewer people and reducing their overall carbon footprint.

This includes International Hydrographic Organization (IHO) classified Special Order standard surveys, which are often specified for pre- and post-surveys underwater power cables and UXO surveys.

To meet navigation requirements, Special Order surveys in shallower waters tend to require ship-mounted sensors, to achieve the absolute positional accuracy required (using the vessel’s RTK/GNSS position).

In deeper waters, heavier, larger diameter AUVs are used. Because they rely on a DVL and an inertial navigation system (INS) for their navigation, they also must be supported by large vessels.

But what if you could perform Special Order surveys in shallower coastal waters with smaller low-cost AUVs, reducing your reliance on large vessels, reducing logistics, emissions and operational costs?

This was the challenge set by customers of L3Harris who were keen to find ways to use their Iver3 AUV for Special Order surveys.

Specifically, they set out to test if USBL-aiding at high enough accuracy for Special Order surveys could be achieved within the size, weight and power limitations of a smaller, light weight AUV platform, such as the 5.8 in-diameter Iver3.

If it could, it would allow underwater run-times of more than eight hours, and a new paradigm in lower operational cost coastal surveys.

The solution

L3Harris had already used our Mini-Ranger 2 for USBL aiding an iXblue Phins INS, via one of our AvTrak 6 OEM Nanos, on one of its Iver3s on a separate customer project. Read more here.

Mini-Ranger 2 is the ideal USBL system for coastal operations, supporting high-elevation tracking of up to 10 targets simultaneously down to 995 m water depth (extendable to 4,000 m), as well as data harvesting. It offers performance without the cost and complexity of a larger deep water USBL system.

At the heart of the system our HPT 3000, a highly capable surface deployed USBL transceiver which is optimized for performance in shallow water, high elevation and long lay back operating scenarios, as well data telemetry.

To provide INS aiding, L3Harris’ customer chose to integrate our AvTrak 6 OEM Nano, with a remote transducer, into their Iver3.

AvTrak 6 OEM Nano is the smallest variant of our AvTrak transceiver, designed for ease of integration on smaller underwater vehicles. It combines the functions of a transponder, transceiver and telemetry link, enabling communications, tracking and USBL aiding for subsea robotics. It’s also based on our 6G hardware platform, which means it’s interoperable with all our USBL, LBL and INS systems. This provides flexibility, but also performance enhancement, for example when combined with a Sonardyne INS.

As in the earlier project, the AvTrak 6 was programmed to speak the right language to the third-party IXBLUE Phins INS, by sending out an APOS PSIM SSB telegram, instead of our proprietary SPOS. The AvTrak 6 transducer was also supplied on a special Iver3 mounting post design, to make it easy to plug and play into the AUV – and any other Iver3, for that matter.

Mini Ranger 2 was pole-mounted to the support vessel with hemisphere GPS for topside absolute positioning.

The results

L3Harris ran a <5 km-long survey, with six 800 m legs, in challenging <20 m water depth in Narraganset Bay on the north side of Rhode Island Sound.

Real-time USBL-aiding improved the survey accuracy by upwards of 7 m on far end of survey legs through the turns. During the survey, real-time survey performance ranges up to 800m were tested with USBL position standard deviations ranging from 1 – 3 m.

In addition, using Mini-Ranger 2’s robotics pack, the L3Harris team were able to provide the vehicle with information of the acoustic environment, so its autonomy could make decisions to adjust the AvTrak 6 OEM Nano’s power and gain settings to improve acoustics without a human in the loop.

“The standard deviation on the USBL position fixes were accurate allowing real-time position updates to the INS. The ease of operation using the Mini-Ranger 2 topside to track and monitor environmental influences throughout the survey also added a layer of safety for monitoring the UUV.”

“This set up allows surveyors to meet Special Order navigation standards, which is a big deal for small unmanned underwater vehicles (UUVs),” says John Sloat, Application Engineering Lead, L3Harris. “The problem before has been that there’s not a lot of real estate inside smaller UUVs to house the onboard technology required for Special Order navigation capability in. But now they can.

“This capability adds a high level of survey efficiency by reducing the need to frequently surface for a position fix which increases the vehicles endurance, reduces the risk of vehicle entanglement or loss, and allows for larger areas to be surveyed. It also means they have real-time data vehicle positioning, which, when post-processed, could be improved even more. That’s really valuable to survey customers and we do see this as the cusp of a new UUV survey era,” adds John.

What was also hugely valuable to the L3Harris team was the support from Sonardyne’s experts.

“The level of support and service from Sonardyne has been exceptional,” says John. “We are very pleased. It’s been a fantastic experience at every phase of the integration we have done and that’s a big de-risk for us, having a partnership like this.”

“The real-time improvements on the survey navigational position accuracy were nothing short of exceptional, offering a powerful capability to improve survey accuracy using small UUVs,”

Morgan Eash Applications Engineering Manager, L3Harris AUV Systems

A 'custom-off-the-shelf' product provides a timely solution for Dana Petroleum

Our experience and expertise allowed us to rapidly adapt our off-the-shelf technology for Dana Petroleum. This delivered a cost-efficient, low environmental impact, and timely solution for them to monitor their suspended wells in the North Sea.

The challenge

As they reach the end of their productive life, oil and gas well heads still need to be monitored whilst suspended – for up to five years, before they become fully abandoned / decommissioned. A regime must be in place to monitor the assets ‘in perpetuity’ to meet government regulations. As this is ‘abandonment expenditure’, rather than capital expenditure, any monitoring schedule must be conducted as cost effectively as possible.

Dana Petroleum (Netherlands) was faced with one such challenge in early 2023 when they needed to plan and implement a well annulus monitoring schedule for suspended wells at their Van Ghent and Van Nes subsea wells, situated in the North Sea approximately 60km West of The Hague. The wells were situated alongside others still in operation and although the topside platform remained, communication links with the sensors on the suspended subsea wells had been lost. There was an additional challenge of the system needing to be in place within 12 weeks.

The solution

The ’simple’ solution would have been to lay new communication cables from the suspended well heads to the topside platform to enable the monitoring. But this would have been lengthy, expensive and carbon intensive, involving bringing in large vessels to lay long stretches of subsea cables. A quicker, cost effective and lower carbon solution was needed. Having heard about Sonardyne’s experience and expertise in long-term subsea asset monitoring, Dana Petroleum approached us for a solution.

We have many years’ experience in providing subsea pressure and temperature data directly from well downhole gauges, mostly during the appraisal phase in a field development, providing essential data to the reservoir engineers before connection is made to the offshore or onshore facility.

Although Dana Petroleum’s requirement was well within our capabilities, there were some initial unknowns such as; field layout, pressure gauge model and manufacturer and how the equipment would be mounted to the subsea manifold. Also, which topside would be most suitable for data harvest? Something which is typically dictated by the vessel size, noise profile and water depth. The timeframe was also very challenging.

In the following weeks, Dana Petroleum provided information on the field layout, drawings of the subsea infrastructure and a strong specification for a system capable of monitoring the annulus pressures at both locations. Having received this, we were able to provide illustrations of previously designed bracketry, 3D CAD images of our potential offering and expert advice to work out the optimum placement to enable best line of site for data harvesting. With a firm specification and known time constraints we looked to our off-the-shelf products with a view to creating a semi-custom solution with our projects team.

The obvious choice was to make custom alterations to our Autonomous monitoring transponder (AMT). The AMT has been used in a wide variety of different applications including overburden monitoring and pipeline movement monitoring, all utilising and autonomously logging pressure sensor data. These solutions can operate autonomously over long periods of time, over five years – depending on deployment – logging data and making it accessible for wireless upload.

The topside platform of choice was a Nano topside equipped with a ruggedised laptop running Sonardyne’s Monitor software fitted to a small crew transfer vessel that would pass by the wells at regular intervals, delivering workers to the platforms. The size of the vessel dictated a small portable solution but other options are available for all sizes of vessels.

Once the seabed and topside products were selected, custom modifications were made by the projects team to the AMT, allowing the pressure sensor to be connected to the annulus via a flange – rather than inside the AMT –to give flexibility in the location of the AMT and achieve best line of communication with the Nano transceiver when it passed overhead.

A factory acceptance test was witnessed by Dana Petroleum where our projects team provided documentation and coordinated the testing. Following this the equipment was shipped and ready for installation – all within a few months!

The results

The AMTs were installed by N-Sea using the diving support vessel EDT Protea and acoustic connection was established to test the pressure gauges. Readings came back as expected and the system was set logging. Following several days of logging the vessel returned to each well head to harvest the data and prove the system.

Significant cost savings were made by removing the need for new cable infrastructure and utilising a crew transfer vessel for data collection. This also dramatically reduced the carbon footprint of the monitoring schedule.

To fully verify the installation, valve settings were changed at the De Ruyter platform and this was visible in the data. The graph above shows a steady increase in pressure after the valve was opened on 13/07/23. The notable drop in pressure between 14:10 (UTC) and 20:10 (UTC) on 17/07/23 shows when the valve was closed.

“With energy transition currently very high on most Governments agendas, there is a high volume of suspended wells globally that require a form of long-term monitoring. The current high demand for vessels and drive towards a carbon neutral planet means that traditional methods of monitoring are not always going to viable.

However, regardless of the political and economic environment, assets still need monitoring in a safe and responsible way and that’s where Sonardyne comes in. We have a flexible approach to projects where we can provide exactly what the client needs. Whether it’s equipment to monitor a single well or provision of the raw data for a full multi-well campaign, we have the in-house experience.

When I received the initial enquiry from Dana Petroleum, as a previous member of the technical team it was actually quite exciting as I had been looking for an opportunity to drive a low-cost robust solution that fits well within abandonment expenditure budgets.

We have shown all of this is possible to do and provided the system in a very short timeframe.”

Colin Sutherland Sales Manager, Sonardyne

“Subsea issues like communication or power loss are one of the most difficult items to deal with. With existing systems, normally the only option is to do a complete reinstallation, resulting in huge costs and environmental impact. The solution offered by Sonardyne not only bypasses the communication and power loss, but also offered a cost-effective means of reinstating the pressure monitoring, all within a couple of months’ time.”

Richard Bus Senior C/E/I Engineer, Dana-Petroleum

Contact our custom engineering team

Over the horizon robotic data harvest aids Shell's net zero ambition

Sonardyne, working with XOCEAN’s uncrewed surface vehicles (USV), deliver a lower cost, lower risk and lower carbon, remote acoustic data harvesting service to Shell from their Ormen Lange gas field in the Norwegian Sea.

Shell’s Ormen Lange gas field is a deep-sea site 120 km / 75 miles off the coast of Norway. As Norway’s second largest gas producer, it plays a key role delivering stable gas supplies to Europe. Built on the site close to Storegga, a major landslide which occurred some 8000 years ago, about 5 million tonnes of rock was used to prepare the seabed for subsea equipment back in 2005. The field has been operational since 2007. Ormen Lange is distinctive in that it doesn’t have conventional surface operation platforms.

Close monitoring of any seabed movement is key to prevent any potential impact to the pipe system. Monitoring of the ocean floor around the well heads is conducted by seabed sensors. The first monitoring array at the site saw 203 Acoustic Monitoring Transponders (AMTs) installed in 2011. These sensors enabled monitoring of changes in pressure and tilt to provide an understanding of seabed movement.

This array was recovered in 2016 due to battery limitations and uncertainty in drift. Today the monitoring is undertaken by an array of 75 Sonardyne seabed Pressure Monitoring Transponders (PMTs). Shell took the decision to install 30 PMTs in 2019 with a further 45 installed in 2020.

The challenge

Without surface platforms, acoustic data from the subsea sensors had to be harvested by crewed vessels in the early years of the field’s operation. This was costly, carbon heavy and posed a risk to personnel in often challenging sea conditions.

With a company ‘Powering Progress’ strategy to achieve net-zero emissions by 2050, Shell was looking for an alternative data harvest method that would reduce cost and risk as well as its carbon footprint.

The solution

Marine robotic platforms provide the opportunity to remove carbon and personnel risk. Working with the customer and XOCEAN as a sub-contractor we developed a solution that would save time, costs. and carbon, while also eliminating the human risk element, using a USV to conduct the data harvest.

The proposal was to use our HPT 3000 transceiver mounted to an XOCEAN USV to remotely harvest data from the 75 seabed PMTs. The HPT 3000 is perfect in terms of size, weight and power for deployment from a USV and can communicate with seabed transponders at depths up to 995 m (or 4,000 m with an extended range version).

XOCEAN USVs are perfect for the data harvesting mission at Ormen Lange. They enable full over-the-horizon 24/7 operations. This means that operators and data analysts can remain safely onshore whilst the operation takes place and data can be sent ashore and verified in near real-time using the USV’s satellite communications.

This satisfied Shell’s commitment to accelerate the transition of their business to net-zero emissions and to integrate sustainability within their business strategy. Following the successful PMT installation in 2019, a five year project was agreed where Sonardyne are responsible for the data delivery to Shell and XOCEAN are responsible for delivering the transceiver to the field for data collection via their USV.

The results

The project began in January 2020 and this was the first time a remote USV data harvest was completed offshore in Norwegian waters by any operator.

Whilst the USV and HPT 3000 were in Norwegian waters surveying the Ormen Lange site, the Sonardyne and XOCEAN personnel never left their bases in England and Ireland.

The data harvest was monitored in real time, 24/7 and the two teams were in contact with each other as well as the remote equipment. This mean that data was being monitored by our team as it was collected and there was no risk of the USV returning with missing or irrelevant data. Had there been any missed or partially collected data the Sonardyne team could ask the XOCEAN team to return to recollect from a particular PMT whilst still in the field, rather than waiting until the vessel returned and having to send it out again.

Successful data harvests have been conducted yearly since 2020 and continue to be a cost effective, low impact operation. This year we collected data from the Ormen Lange site twice, in Spring and Autumn.

If you think you have a similar challenge for us, contact us today.

XOCEAN says

“Through the successful PMT data harvest campaigns at the Ormen Lange Field, XOCEAN has demonstrated reliability by leveraging our cutting-edge USV technology in partnership with Sonardyne. Our uncrewed survey vessel platform offers a safe, reliable and low carbon solution for the delivery of ocean data. As we continue developing our remote operations, we recognize its pivotal role in steering the world towards the realization of the UN Sustainable Development Goals.”

Tomas Frafjord Norway Country Manager, XOCEAN

Sonardyne says

“Transforming how data is harvested at the Ormen Lange site and the on-going success of this project demonstrates the current and future potential of marine robotics in offshore operations. Moving from crewed to uncrewed vessels for such operations enables the drive to reduce carbon emissions in marine industries. Similar remote data collection solutions can be realised in any marine operation that requires long-term data collection. Where Sonardyne communications are built into seabed sensors we can communicate with them using instruments fitted to marine robotic platforms.”

Aidan Thorn Business Development Manager – Marine Robotics, Sonardyne

Norske Shell says

“In Shell we are always looking for new, innovative ways of working that can reduce risk to both people, assets and the environment. Uncrewed surface vessels have proven a highly suitable vessel for downloading PMTs. Carbon emissions are reduced to almost zero, and we don’t need to send people offshore anymore for the downloads. Considering the long distance from shore to field and the often unstable weather conditions in the area, solid planning and vessel management is essential.”

Egil Syre Project Manager, Norske Shell

Autonomous robots prepare to storm the ocean depths

Sonardyne were delighted to be part of the trials of a fleet of marine robots able to tackle complex offshore tasks as part of a ground-breaking project funded by Innovate UK, which is poised to change approaches to ocean exploration. Autonomous marine systems are being developed and deployed in increasing numbers. However, as maritime operations become ever more complex and expensive, and installed energy infrastructure increases in scale and distance from shore, there is a rapidly emerging need for more sophisticated multi-platform capabilities in the offshore renewable energy (ORE) market.

Squads of Adaptive Robots (SoAR) is a two-year collaborative research project, led by the developer of ecoSUB autonomous underwater vehicles (AUVs), Planet Ocean. The project kicked off in September 2021 and culminated this summer with full system testing at Smart Sound Plymouth on England’s south coast.

The SoAR team’s aim was to demonstrate how large-scale survey and exploration missions can be achieved by going beyond the limitations of individual AUVs. We worked alongside industry and academic partners; Planet Ocean, HydroSurv, the National Oceanography Centre (NOC), Royal Holloway University and the Offshore Renewable Energy (ORE) Catapult to develop advanced AI-driven mission planning, communications protocols for fleet coordination and significant improvements in underwater navigation and communications technology.

The trials simulated an offshore windfarm concession survey mission informed by a comprehensive business case analysis by the team at ORE Catapult.

The technology

The fleet-level autonomy engine developed by Royal Holloway, University of London served as the mission’s central nervous system, making real-time decisions and replanning when necessary due to factors such as inaccurate mission execution, vehicle faults, changes in the operating environment or the addition and removal of stations. The division of labour enabled by this approach showed significant promise in productivity gains made possible by robotics and AI.

The SoAR Communications Backbone, developed and released by the team at the NOC, acted as a central messaging system which enabled interoperability between the fleet-level autonomy engine, each vehicle-specific command and control system and any other sub-system requiring bi-directional communication. This was key to allowing the seamless introduction of different platforms and sub-systems in diverse combinations to suit a wide range of mission objectives.

We provided inter-medium communications via our AvTrak 6 Nano acoustic transceivers fitted to each AUV. This enabled simultaneous USBL tracking via a surface vessel and robust telemetry for AUV-to-vessel and AUV-to-AUV communications.

A small swarm of four ecoSUB AUVs, each fitted with an AvTrak 6 Nano acoustic transceiver, played a crucial role in rapidly assessing the underwater environment and conducting preliminary evaluations to identify targets of interest.

An Auto-Hover 1 (AH1) AUV, owned and operated by NOC, capable of exceptional precision in maintaining station and navigating vertically within the water column, and fitted with an AvTrak transceiver, was dedicated to close inspection tasks, enabling intricate and comprehensive examination of identified targets.

Our HydroSurv REAV-60 uncrewed surface vessel ‘Decibel’ assumed a pivotal role, serving as a crucial communications gateway to and from the AUV swarm. It was fitted with an HPT 3000 transceiver and ran our well-established Ranger-2 software on its topside, facilitating inter-medium communication and providing navigation support to the AUVs. Decibel was also equipped with various communications devices including 4G/LTE and Iridium satellite communication systems to enable communications between subsea, surface and the Autonomy Engine.

The deployed SoAR fleet was managed and controlled from HydroSurv’s shore-based Remote Operations Centre in Exeter, using 4G/LTE and Iridium communications.

The results

The open-water trials successfully showcased co-ordinated missions designed, monitored and adapted in real-time by an intelligent “Autonomy Engine”. The trials involved several surface and underwater autonomous systems, with mission management conducted from a remote shore-based command and control facility.

SoAR has led to the introduction of several technological innovations, including advanced AI-driven mission planning, open-source communications protocols for heterogenous fleet coordination and a range of new and enhanced platform capabilities for both surface and sub-surface systems. The variety of small form factor robotic platforms involved in the project represented some of the best innovation in UK ocean robotics to date.

The SoAR concept is adaptable to various applications but strategically tailored to address the specific needs of the offshore wind sector, developing an approach that will offer new operating paradigms and substantial long term cost savings for offshore asset construction and maintenance compared to conventional methods.

SoAR received funding from the ‘Next Generation Subsea Technologies’ competition, a joint initiative supported by Innovate UK, the Net Zero Technology Centre and the Royal Navy.

Delivering subsea synergy in ORE inspections

There are numerous challenges associated with offshore wind visual inspections, including currents, turbidity, time and cost. Sonardyne, EIVA and Voyis, all part of the Covelya Group, are working together to bring a complete imaging, navigation and autonomy solution to overcome these obstacles and enhance the inspection data product.

With almost a century of combined subsea expertise between them, the companies are ideally placed to offer a solution to the offshore renewable energy (ORE) market that is even greater than the sum of its parts.

Combining great experience to create even greater things.

Bringing together their combined expertise at a technology accelerator event at the ORE Catapult Subsea and Marine testing facility in Blyth, Northumberland, UK, Sonardyne, EIVA and Voyis were able to demonstrate the potential of their ORE inspection solution to industry users, vehicle manufacturers and end clients recently.

Each company brought its own existing technologies which were integrated, on remotely operated vehicles (ROVs) provided by Atlantas Marine , to demonstrate an even more effective solution for underwater surveying.

During the demonstration, NaviSuite VSLAM leveraged the Discovery Stereo system to enable augmented piloting through real-time 3D point cloud images for quality control, while NaviSuite Mobula provided an end-to-end software solution for acquisition, processing and delivery of data.

Sonardyne SPRINT-Nav Mini

Sonardyne’s SPRINT-Nav Mini provides robust, reliable, navigation for piloting and surveying. It is the world’s smallest hybrid acoustic-inertial navigation system and can be used as an all-in-one vessel and marine robot navigation instrument with performance beyond its size. The SPRINT-Nav Mini eliminates the need for separate sensors, such as AHRS, DVL, INS, and depth sensors. This results in no further calibration requirements, fewer cables and connectors to manage and it is more cost-effective than the four sensors it replaces.

It will work in the most challenging environments and remains unaffected by steel structures such as wind turbine foundations and provides a continuous stream of positions, orientation, velocities, depth and altitude at up to 200 updates per second.

SPRINT-Nav Mini

Voyis Discovery Stereo camera

Voyis’ Discovery Stereo camera provides a powerful platform for a vehicle’s subsea vision needs, delivering stills images, video, IMU data and 3D data with a data-centric DDS architecture. Through edge computing, it integrates with EIVA’s visual simultaneous localisation and mapping (VSLAM) software technology to provide real-time 3D reconstruction, ensuring area coverage mapping and augmented piloting. Mounted on the front of the ROV, the Discovery Stereo provided 4K video stream and high-resolution images for both navigation and inspection throughout the demonstration.

Discovery Stereo

EIVA NaviSuite Mobula

EIVA’s NaviSuite Mobula software package provides a complete topside software solution for the ROV, enabling efficient acquisition of data with the Voyis Discovery Stereo and Sonardyne SPRINT-Nav Mini. This software offers unique capabilities for automating remotely operated subsea inspection and surveying operations – using tools for a wide variety of tasks, leveraging the software toolbox of NaviSuite.

NaviSuite Mobula

Demonstrating the difference.

The technology accelerator event at Catapult provided the perfect opportunity to showcase the possibilities in developing this combined subsea inspection solution. The test dock contains a turbine foundation and various other structures, perfect for subsea navigational and photogrammetry demonstrations.

The ROV was fitted with a SPRINT-Nav Mini at the rear, Discovery Stereo camera at the front and utilised the NaviSuite Mobula and VSLAM software packages to control the ROV movements, represent the operation in a real-time 3D visualisation and pilot view, along with monitoring coverage and inspection data quality.

Once the ROV was launched, focus shifted to the control room where the assembled delegates watched the live 4K video stream from the Discovery Stereo camera as the vehicle navigated the dock.

Whilst its primary navigation and positioning was provided by the SPRINT-Nav Mini, as the ROV navigated and surveyed the subsea structures the Discovery Stereo camera and NaviSuite software combined their capabilities to provide millimetric positioning precision and 3D point cloud detail which was fed back to the control room. A video from the demonstration, giving more information about the technology, can be viewed here.

In real-life operations, these actionable insights could then be used to make immediate decisions about state of the asset, the quality of the data and subsequent actions required from the ROV. Having the capability to make real-time operational decisions greatly reduces the risk of collecting inaccurate data and helps to avoid the associated wasted time and cost.

For Sonardyne, EIVA, Voyis and the wider Covelya Group, this demonstration of synergetic working is just the beginning of our ‘Better Together’ approach. The opportunities for delivering smarter, faster, cleaner and more effective subsea technology solutions from within the group of companies are almost endless.

“The benefits of coming to the Covelya Group for an integrated subsea inspection solution is a tight integration of our complementary products in the world of subsea communication, navigation and data acquisition across the group.”

Phillip Hart VP of Integrated Technology, Covelya Group

Robotic inspections ensure fish nets are securely anchored

With precise positioning a priority in fish farm mooring maintenance, Aquasky Ltd needed a reliable tracking system for their remotely operated inspection vehicle (ROV). Find out how Micro-Ranger 2 proved equal to their challenge.

The challenge

In aquaculture, second only to the welfare of the fish, the maintenance and exact positioning of the nets and their moorings is critical. With specific areas set aside for fish farms, it’s important that the nets don’t drift out of place or into shipping lanes. To maximise production, fish farmers need to moor as many nets as possible within their area whilst ensuring the moorings don’t damage each other. All of this requires careful and precise placement and inspection, which is where Aquasky Ltd excel.

Aquasky Ltd first operated as a small diving company servicing local fish farms along the west coast of Scotland. During 2011/13 it branched out into moorings inspections using a Videoray Pro 5 ROV. They continued to grow and now provide their services to all the major fish farm companies operating in Scotland plus some others abroad.

As the aquaculture industry has grown so has the size and complexity of its subsea equipment. Aquasky Ltd use an ROV to inspect mooring lines and anchors is to verify their integrity and location. The number of anchors can vary from 26 to over 60 for each site depending on the size of the farm.

Accurate identification of anchor positions is essential. Farmers must ensure assets remain within their lease areas as moving outside can lead to suspension of the lease, with significant financial impact.

It is also essential to maintain separation between moorings to prevent any damage. Anchors being incorrectly positioned can result in the following causes of mooring failure: –

  1. Anchor chains rubbing through the mooring ropes.
  2. Mooring ropes contacting rocky reefs and rubbing through.
  3. Moorings being positioned where the anchors cannot locate firmly into the seafloor, for example on clean rock.

In the event of mooring failure, movement of the cages can initially result in the nets coming into contact with the submerged farm grid system. The nets are then squashed, and the fish are forced into a very small area with reduced oxygen available, resulting in them becoming stressed and dying.
In the event of catastrophic failure, cages can break away and drift ashore or out to sea, resulting in the fish escaping into the wild population.

As part of the inspection process, Aquasky provide their clients with detailed reports confirming the location and condition of the moorings.

In order to meet their requirements, Aquasky needed a positioning system that was accurate, compact enough to fit on a small ROV, reliable and portable so that it could be transported to and used in all of their clients’ locations, including those abroad.

Aquasky
Aquasky
Aquasky
Aquasky

The solution

Portable and quick to mobilise, our Micro-Ranger 2 USBL system can be used from any waterside location or vessel to track divers, underwater vehicles and equipment. Ideal for using in lochs and challenging water.

It is our smallest ever underwater tracking system. Everything is engineered to fit in one medium-sized carry case. Apart from a laptop to run the software, nothing else is needed and the size is so small, it can be carried on a plane. Perfect for when Aquasky find work outside of Scotland.

For their anchor and mooring inspections, Aquasky attach a Micro-Ranger 2 Nano transponder to their ROV which then travels around the fish farms. A transceiver is mounted on a vessel nearby and acoustic signals between the transponder and transceiver are used to establish the ROVs, and therefore the anchor/moorings, position. This position can be displayed for in-water tracking and output in real world co-ordinates for interfacing into external chart plotting systems for the clients reports.

“We needed an accurate positioning system that continues to work as mooring lengths increase and in a noisy subsea environment. Having used other cheaper systems, the Micro-Ranger 2 is the only one able to consistently supply reliable positions for anchors at the 300m length currently used by the farms we service.“ Steve Barlow, Founder, Aquasky Ltd.

 

The results

By adding Micro-Ranger 2 to their subsea inspection tool kit, Aquasky Ltd are able to provide a service that has become the industry standard for fish farm inspections. Their use of an ROV means that inspections are quicker, safer and less expensive than traditional diver inspections. Using Micro-Ranger 2 ensures that the ROV never gets lost and provides accurate data which is vital for the inspection reports.

If you have a similar challenge that needs a subsea tracking solution, give us a call

“We needed an accurate positioning system that continues to work as mooring lengths increase and in a noisy subsea environment. Having used other cheaper systems, the Micro-Ranger 2 is the only one able to consistently supply reliable positions for anchors at the 300m length currently used by the farms we service.”

Steve Barlow, Founder, Aquasky Ltd

“Aquasky’s use of our Micro-Ranger 2 is a great example of its versatility for application in a different marine market sector. Using it for their ROV operations has allowed Aquasky to set the industry standard for fish farm monitoring and inspections. We are delighted to have supported them in doing this and look forward aiding their future operations.”

Alan MacDonald, Head of Sales, UK, Europe and Africa, Sonardyne

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Mapping the future for seagrass beds in Plymouth Sound

Seagrass beds are incredibly important ecosystems that offer a range of ecological benefits. Not only do they provide crucial habitats for a diverse array of marine wildlife, especially in coastal areas like Plymouth Sound, they can also store carbon, helping to mitigate the effects of climate change. These underwater meadows serve as nurseries for many species of fish in the early stages of their life, offering them protection and abundant food sources. Additionally, seagrass beds help to stabilise the seabed with their root systems, preventing coastal erosion and maintaining water quality by trapping sediments and nutrients.

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Drake seabed
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Seagrass map

However, despite their importance, locating and monitoring seagrass beds using traditional methods, such as survey boats, presents significant challenges. Seagrass typically grows in shallow waters, which can make it difficult for boats to navigate close enough to the shore to obtain accurate data. Traditional survey boats are often large and cumbersome, making them hard to manoeuvre in shallow or rocky areas. This limitation can result in incomplete or inaccurate assessments of seagrass distribution and health.

Furthermore, the process of using boats for surveying can be time-consuming and labour-intensive. It often requires multiple trips and extensive manual labour to map out the seagrass beds accurately. The visibility in shallow waters can also be poor due to water turbidity, further complicating the survey efforts and leading to potential underestimation of seagrass coverage.

Finding a solution…

This is where Sonardyne and Wavefront Systems come in. The solution, which combines Sonardyne and Wavefront technology, is a survey boat carrying Solstice MAS™ (Multi-Aperture Sonar) as well as a SPRINT-Nav Mini mounted to a pole, deployed over the side of the boat; this maps the chosen area in 200 m wide strips. Once this survey has been completed, the sonar data that has been captured is then processed to create a map of the seagrass in a GIS. A Remotely Operated Vehicle (ROV) is then sent to the same area to ground truth features on the seabed to check that they are how they have been interpreted by Solstice MAS. The ROV is fitted with SPRINT-Nav Mini, allowing us to track its position underwater and guide it, using the map, to the features identified by Solstice; the ROV is also fitted with a camera and the recorded video can be used to create 3D models of the seabed.

Wavefront Systems’ Solstice MAS uses sound signals to produce high-quality images of the seabed, capable of creating images 200 metres wide at high resolution even in shallow water environments, all while consuming very little power. The Solstice family of sonars are built on unique MAS technology and are designed to fill the gap between standard side scan sonars, which are typically simple in design but give low image resolution, and Synthetic Aperture Sonars (SAS), which are expensive, more susceptible to complete data loss due to platform movement and also produce vast amounts of data. In order to execute more detailed mapping, Solstice MAS requires a high quality navigation sensor, which in this case is SPRINT-Nav Mini.

SPRINT-Nav Mini is an all-in-one vehicle guidance and navigation instrument, which combines AHRS data, Doppler Velocity Logger (DVL), Inertial Navigation System (INS) and depth sensor into a single housing. Having SPRINT-Nav Mini fitted onto the ROV provides positioning input, as well as attitude and heading data.

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Adopting these technologies on such small versatile platforms opens the possibility of high-grade survey data in shallow waters. As a result of the cross Covelya Group collaboration between Sonardyne and Wavefront Systems, a high-definition map of seagrass beds can be created with a greater degree of accuracy than was previously possible with more traditional methods.

A seagrass restoration project conducted by the Ocean Conservation Trust (OCT) in Plymouth Sound, which involves monitoring, conserving and expanding the existing seagrass beds can be enhanced with the use of an ROV which has SPRINT-Nav Mini fitted to it. To help grow the existing seagrass beds, the OCT are placing seagrass mats on the seabed in Plymouth Sound. A survey boat fitted with Solstice and SPRINT-Nav Mini followed by an ROV fitted with SPRINT-Nav Mini can then be used to monitor and create a map of where these mats have been placed so that they have a better understanding of the success of the restoration and expansion project.

“Collaboration is key to our success as a business as we strive to offer integrated solutions to key markets and applications. Our operating companies run independently. However, the overall value when they come together can be significantly more than the sum of their parts. Coupling Wavefront’s Solstice multi-aperture sonar with high performance inertial navigation solutions from Sonardyne and applying it to significant sustainability initiatives such as mapping and monitoring the extent of seagrass beds on the South coast of the UK, makes the effort all the more worthwhile. Great job by the team, continuously innovating to realise increased efficiency and higher value datasets for such worthwhile causes.”

Phil Hart, VP of Integrated Technology, Covelya Group

“We use Wavefront’s Solstice multi-aperture sonar to map seagrass because it provides high-resolution images out to 100m on each side of the vessel even in shallow water. The sonar images give us both a broad and detailed view of marine habitats which is hard to create using other methods. Solstice produces reliable and repeatable results so is ideal for measuring and monitoring changes to the seabed. Solstice also requires very little processing and is compatible with standard side scan processing software, so we find it an efficient solution for habitat mapping over large areas.”

Peter Holt Marine habitat monitoring applications specialist, Sonardyne

Revolutionising small ROV navigation

Operating a small robotic platform in any marine environment is not without its challenges. Reliability and precision with accurate positioning data are key for safe operations and where repeat inspections or surveys are needed.

The size of the platform may present its own limitations, restricting the size and weight of any payload and therefore the extent of its operational capabilities. Environmental or locational factors may also play a part in the reliability of operations. Most navigational and positioning payloads use magnetic compasses to provide heading.

This reliance on magnetic heading makes the platform susceptible to interference from ferrous materials in its surroundings. These could be wind turbine or energy platform monopiles, wreckage or unexploded ordnance (UXO) on the seabed, the presence of vessels / submerged infrastructure in harbours and coastal locations or even just naturally occurring ferrous minerals in the seabed.

These factors introduce heading errors that compromise the supervised autonomous functions of the platform, particularly when following line headings between reciprocal bearings. Even minor heading inaccuracies can cause cumulative deviations over extended missions, leading to imprecise data and potentially requiring time-consuming survey line re-runs.

Any inaccuracies during survey when locating UXOs are particularly unwelcome, by their nature most UXOs are located based on magnetic signature. So, any poor navigation during the wide area or detailed UXO survey can be misleading and potentially dangerous. With repeat inspections of monopiles, for example, ensuring the survey platform returns to the exact same spot on each visit is important to ensure no anomalies or potential problems are missed.

The challenge

Atlantas Marine are a market leader in ROV inspection services. They are regularly called upon to inspect an area for UXO prior to operations or to survey installations at sea. One such example was at the Port of Dover in the UK where Atlantas Marine deployed a VideoRay Defender equipped with an Oculus M750d Multibeam sonar for high-resolution imaging and an ELWAVE TetraPulse system to search for UXOs prior to the deployment of a jack up vessel for remedial work in the port.

At the time of the survey, Atlantas Marine’s VideoRay Defender ROV relied on a magnetic compass for its Attitude and Heading Reference System (AHRS) for navigation and orientation. Richard Stanley, Project Leader at Atlantas Marine explains the mission;

“During the subterranean survey, we utilised a skid-mounted system beneath the ROV equipped with four electrodes to measure electrical impedance up to 2 metres from the vehicle (ELWAVE TetraPulse), targeting both ferrous and non-ferrous UXOs. In the target-rich environment of the port, ferrous objects affected the magnetic compass within the AHRS, resulting in a heading drift of approximately 5-10°.”

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If you have a similar challenge in your small robotic platform operations, talk to us about how we might help you to find the solution

The solution

Recognising the need for precise navigation for smaller survey and inspection robotic vessels, Sonardyne set about finding a solution. For over a decade the SPRINT-Nav family of hybrid navigators have combined INS, DVL and pressure sensors with either ring laser gyros (RLGs) or fibre optic gyro compasses (FOG). Unlike most standard fit ROV heading sensors, FOGs don’t rely on magnetic North for positioning and so their operation is not affected by any ferrous objects around them.

Having the technology was one thing, but there was the additional challenge of making it small and light enough to work with vehicles that are often less than a metre in length and only a few kilograms in weight themselves. They also often need to be launched by hand and carried onboard larger vessels, so the size of the payload is imperative.

In response to this challenge facing many small ROV operators like Atlantas Marine, Sonardyne developed SPRINT-Nav U, the world’s smallest hybrid navigator, combining INS, DVL and a pressure sensor in one factory calibrated unit.

“Historically, smaller electric vehicles have been limited in the amount of work they are capable of due to size, power and operational limits presented by weather conditions and surroundings.

Recent iterations of handheld ROVs such as the VideoRay Defender have looked to change what electric ROVs are capable of, while maintaining a platform that is easy to mobilise, operate and maintain. That said, the ROV is only as powerful as the tooling that it holds, so it still requires support from companies such as Sonardyne, to reduce the form factor and weight of their tools and sensors, to enable their integration and deployment offshore.

Atlantas Marine have already been utilising the SPRINT-Nav Mini to great success on our Ocean Modules V8 M500 platform, but Sonardyne’s latest navigator, SPRINT-Nav U, will allow us to go further and integrate it onto our VideoRay Defender ROVs, and provide another service that we can offer our customers – a hand-launched ROV, that can be mobilised in as little as half an hour, transported to site in the back of an car” Mark Salter, Senior Project Manager, Atlantas Marine.

“Like the other hybrid navigators in the SPRINT-Nav family, SPRINT-Nav U’s true north seeking gyrocompass means that it delivers reliable subsea navigation even when in close contact with the types of environmental factors outlined above. With its ultra-compact form factor (126 mm X 114 mm) and a weight in water of just 1.04kg, SPRINT-Nav U gives unrivalled navigation capability to small marine robotic system allowing users to maintain a heading accuracy of 0.15° regardless of environmental factors.

“SPRINT-Nav U has been designed with our customers in mind. We’ve been speaking to them for a number of years about their aspirations for operations with small platforms. With the help of valued customers like Atlantas Marine, our trials have demonstrated a variety of use cases for this new, compact navigator and we’re excited to work on many more innovative uses in future.” Aidan Thorn, Business Development Manager – Marine Robotics, Sonardyne.

“SPRINT-Nav U allows us to offer our customers a level of accuracy and precision that was previously not possible”

Mark Salter Senior Project Manager, Atlantas Marine

Small, light, precise

SPRINT-Nav U is simple to integrate into any marine vehicle along with other payload sensors and uses same field-proven web user interface found on the SPRINT-Nav Mini. Pre-calibration in the factory also means that SPRINT-Nav U is incredibly quick to set up and deploy on site with an alignment time of as little as five minutes, compared to the standard 15-20 minutes of other gyrocompassing inertial navigation systems, making it the world’s fastest aligning hybrid navigator.

“SPRINT-Nav U can turn any marine robot into a survey grade platform. For UXO and asset inspection it drastically improves deliverable data quality. As part of the proven Sonardyne SPRINT-Nav family, customers can be assured of reliable, accurate navigation and positioning every time, no matter the operating environment.” John Houlder, Senior Product Manager, Sonardyne.

The results

Keen to offer their clients a solution for operating in new or challenging locations, Atlantas Marine were happy to put SPRINT-Nav U through its paces as soon as it became available. Vobster Quay in Somerset, UK, provided an excellent proving ground as the flooded former quarry contains the wreck of a plane and many other ferrous objects in up to 36 metres of water.

A combined team from Atlantas Marine and Sonardyne deployed a VideoRay Defender equipped with a SPRINT-Nav U payload manually from quayside in Vobster Quay, and after taking around five minutes to align, the Defender was soon navigating the quarry.

Using Greensea software, the Defender was able to successfully perform precise box and lawn mower survey patterns – with less than 0.1% error as a percentage of distance travelled – over the plane wreck without the ferrous materials affecting the navigation.

What the customers thought

Mark Salter, Senior Project Manager at Atlantas Marine – “Of particular significance to us, is the work we undertake on offshore wind turbines. With a high AC voltage running through the subsea cabling, and the strong magnetic signatures associated with that, plus the ferrous nature of the turbines themselves, the SPRINT-Nav U allows us to offer our customers a level of accuracy and precision that was previously not possible. It allows us to state with much higher confidence the location of any faults and anomalies, and allows us to repeat inspections, year on year, as we document the changing condition of those faults. With the positioning and control managed through Greensea, we can set up autonomous routes and sea patterns with more accuracy and precision than even before, especially in the environments we most commonly find ourselves.”

Richard Stanley, Project Leader at Atlantas Marine – “Providing improved accuracy when operating in ports and areas where large metallic objects are buried on or beneath the seabed, improves not only the reciprocal bearings of the lanes the ROV is flying, but feeds a more accurate heading into the navigation solution which is streamed to the surveyor. Beyond seabed surveys, the ability to maintain a stable heading while piloting a compact inspection-class ROV through culverts with rebar or complex subterranean tunnels is a key advantage. It reduces the need for frequent heading corrections and ensures precise navigation when traversing long distances. This ultimately enhances the quality of deliverables for our clients, providing us with a competitive edge when deploying our equipment.”

 

If you have a similar challenge in your small robotic platform operations,

Talk to us about how we might help you to find the solution

Compact navigation solutions enhance Sulmara’s advanced marine geophysical surveys

The drive towards greener offshore energy generation begins well before the first wind turbine blade turns. Geophysical marine survey company Sulmara are innovating the way they work with the offshore energy sector, leveraging technology wherever possible to help offshore wind projects be developed in the most efficient and environmentally sound ways possible. Founded in 2019, they are an international services provider specialising in site investigation, construction support, subsea survey and inspection across the offshore energy and utilities sectors.

The challenge

With a focus on unexploded ordnance (UXO), boulder and linear infrastructure mapping, Sulmara are pushing the boundaries of technologies to deliver depth of burial surveys and identify obstacles in and around potential offshore development sites across the energy sector.

By integrating an ROTV with an Edgetech Buried Object Sonar System (eBOSS) and Micro-Fabricated Atomic Magnetometers (MFAMs) from Geometrics and then layering custom software and delivery packages on top, Sulmara have developed a technology stack capable of enhancing site investigation and asset inspection campaigns. To deliver high quality data with the system that is deployable from a range of vessels and subsea vehicles, Sulmara required very high accuracy positioning and navigation inputs. They were also looking for a way to lighten the payload for towed operations. Sulmara approached Sonardyne as a world-leading supplier of acoustic positioning and hybrid inertial-acoustic navigation technologies to help them rise to this challenge.

The solution

In February 2025, as part of their continuing commitment to pre-commercialisation development, Sulmara mobilised a vessel and survey setup in Norfolk, Virginia USA to perform various trials and data acquisition tasks with a range of sensor equipment. The integrated eBOSS, MFAMs, and ROTV were mobilised and extensively trialled over a range of seabed conditions. For a positioning solution to support the towed platform, Sulmara selected Sonardyne’s Mini Ranger 2 USBL system.

For navigation, Sulmara had opted for an integrated Sonardyne SPRINT-Nav Mini hybrid inertial-acoustic navigator, and they were happy with the navigation performance provided. However, in their drive to make their technologies more compact, any savings on size, weight and power were considered, and Sonardyne sent out members of their engineering team with a prototype of the SPRINT-Nav U hybrid inertial-acoustic navigator to work with Sulmara and utilise this new smaller, lighter and lower powered navigator to the test on the towed platform.

Small, light, precise

Measuring just 134 mm in height, 114 mm in diameter and weighing a mere 600 grams in water, SPRINT-Nav U is the world’s smallest hybrid acoustic-inertial navigator.

Its small form factor packs the full, trusted, SPRINT-Nav capability into a space traditionally filled by just a DVL on a small robotic platform to deliver USBL aided performance up to 4x better than standard, with just 8W of power consumption. SPRINT-Nav U is simple to integrate into any marine vehicle along with other payload sensors and uses same field-proven web user interface found on the SPRINT-Nav Mini. Pre-calibration in the factory also means it’s incredibly quick to set up and deploy on site. An alignment time of as little as five minutes, compared to the standard 15-20 minutes of other gyro compassing inertial navigation systems, also makes it the world’s fastest aligning hybrid navigator.

“The all-in-one and compact nature of SPRINT-Nav Mini and SPRINT-Nav U make them ideal for integration into towfish platforms. Towfish are currently positioned either using magnetic heading sensors or course made good, which may lead to large positioning and heading errors. Affecting both data at nadir and at the edge of a sonar swath. The combination of high-grade fibre optic gyro based IMU and DVL means that our small SPRINT-Nav products provide class leading navigation inputs into the wider towfish system, ensuring reliable data outputs and eliminating any need to re-run lines because of poor navigation.” John Houlder, Senior Product Manager, Sonardyne.

When paired with a Sonardyne Ranger 2 USBL system, in Sulmara’s case the Mini-Ranger 2, the combination of precision navigation and positioning, is second to none.

As our mainstay USBL system for nearshore operations, Mini-Ranger 2 is a tracking, positioning, and communications system with robotic capability that tracks up to 995m out of the box, expandable to 4,000m with an extension pack. It’s suitable for AUVs, divers, ROVs, towfish, USVs, and vessels in shallow to mid-depth waters and features a large array with excellent rear noise blocking, making it ideal for quick vessel mobilisations and long layback tracking in towed surveys.

The results

The combination of Sonardyne Mini Ranger 2 USBL with the new SPRINT-Nav U hybrid inertial-acoustic navigator gave the towed platform a heading accuracy of 0.15°. This was well within the required performance for the geophysical survey specifications that Sulmara are looking to achieve for their clients. Due to the need for location of ferrous materials, such as UXO, having the fibre optic gyrocompass (FOG) inertial measurement unit (IMU) within the SPRINT-Nav U meant that the navigation performance was not compromised in the same way that it would be if the ROTV was using a magnetic heading sensor or course made good for navigation.

“The introduction of the SPRINT-Nav U as a navigation solution for our towed platform provides us with a solution that is not only accurate and reliable in all environments, it also ensured high quality geophysical datasets. It’s low power, size and weight meets our requirement to provide increased manoeuvrability on the ROTV. Pairing the navigation capabilities of SPRINT-Nav U with the Mini-Ranger 2 gives us a great option, as having this one vendor solution means that integration is simplified. The use of a fibre optic gyro is also key; this stops our heading being impacted by any nearby magnetic fields.” Dennis Wilson, Development Scientist, Sulmara.

“Having integrated SPRINT-Nav Mini and SPRINT-Nav U, we’ve been really impressed with the performance of both navigators. The performance of SPRINT-Nav U is really striking for equipment with such a small form factor. This is something we value at Sulmara, as we’re always seeking efficient hardware options to support our innovative survey efforts. We’re increasing the adoption of uncrewed and remote technologies, and it is essential that we do not compromise on the quality of the data we collect when reducing the size of the payload. Having the power of Sonardyne’s SPRINT-Nav products paired with their Mini-Ranger 2 USBL available to deliver guidance for our ROTV operations gives us the reliability needed.” Dennis Wilson, Development Scientist, Sulmara.

If you have a similar challenge in your small robotic platform operations, talk to us about how we might help you to find the solution. Click on the link below and let’s start a conversation…

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