Structural Health Monitoring Sonar

A University of Twente study using Impact Subsea’s ISS360 Imaging Sonar as a structural health monitoring sonar has won best paper at the SHMII-13 international conference on structural health monitoring.

The paper, “2D sonar techniques for monitoring the canal bed morphology of entrances to navigation locks“ by Mohsen Bastani and Rolands Kromanis of the University of Twente, selected the ISS360 from 12 commercial 2D sonars.

They mounted it at the Prinses Beatrix Lock in the Netherlands, where around 50,000 vessels a year wear away the bed protection with propeller wash and bow thrusters.

Scour and loose stones are a growing problem at locks built for smaller ships than today’s. Diver inspections and periodic surveys only capture moments in time, and they’re limited by poor visibility in turbid water.

How the ISS360 works as a structural health monitoring sonar

The sonar saved an image of the bed every minute, and the researchers compared each one region by region with later images. Over a week of scanning, the study showed that the sonar could:

• Detect changes in the bed protection as they happened, including a 0.5m² stone shifting within one minute of a ship passage
• Track loose stones on the lock chamber floor at up to 30m
• Indicate ship drafts and under-keel clearance with the sonar tilted 90°

The researchers conclude that continuous monitoring is essential for catching loose stones early, which visual inspection in turbid water can’t do.

“This project shows that a compact imaging sonar can do much more than navigation. It can be a permanent structural health monitoring sensor for critical infrastructure. Congratulations to the University of Twente team on a well-deserved award.”

Ben Grant, Managing Director, Impact Subsea.

Read the full technical guide: Scour Monitoring with Imaging Sonar in the Impact Subsea Academy.

Download the case study | Read the paper | Learn about the ISS360 Imaging Sonar

To talk about using the ISS360 for monitoring on your site, contact our team or email info@impactsubsea.co.uk.

AUV SLAM navigation

Subsea operators rejoice, you no longer have to compromise size, power or budget for high-performance navigation.

Water blocks GPS signals, forcing Autonomous Underwater Vehicles to rely on dead reckoning, which suffers from unbounded positional drift.

While high-end Inertial Navigation Systems (INS) help, they come with severe penalties in size, weight, power and cost.

A landmark study from the MIT-WHOI joint program (conducted by Andrew J. Motz) has proven that our Impact Subsea ISS360 Mechanically Scanned Imaging Sonar solves this challenge.

Deployed on a REMUS-100 AUV at the WHOI Iselin Pier, researchers used an acoustic Simultaneous Localisation and Mapping (SLAM) pipeline powered by the ISS360 to navigate challenging low-visibility conditions and active tidal currents.

By choosing the ISS360, AUV manufacturers and service providers can unlock elite navigation tracking and advanced structural autonomy without compromising size, power or budget.

Don’t just take our word for it, read the case study below to see the numbers for yourself.

Location

Woods Hole Oceanographic Institution (WHOI) Iselin Pier, USA.

Platform

REMUS-100 AUV

Sensor

Impact Subsea ISS360 Mechanically Scanned Imaging Sonar

Partners

Massachusetts Institute of Technology (MIT) & Woods Hole Oceanographic Institution (WHOI) Joint Program.

MIT-WHOI Validates ISS360 sonar for real-time AUV SLAM navigation Case Study

Autonomous Underwater Vehicles (AUVs) are critical for monitoring subsea infrastructure like offshore wind farms and marine facilities.

Because water blocks GPS signals, AUVs rely on dead reckoning (integrating IMU and DVL data), which suffers from unbounded positional drift. High-end Inertial Navigation Systems (INS) can mitigate this but carry severe size, weight, power and cost (SWaP-C) penalties.

A landmark study by Andrew J. Motz at at the MIT-WHOI joint program proved that the Impact Subsea ISS360 Imaging Sonar solves this problem.

By deploying the ISS360 on a REMUS-100 AUV, researchers developed an acoustic Simultaneous Localisation and Mapping (SLAM) pipeline that eliminated unbounded navigation drift, reducing absolute position error by over 90%.

This system achieved position accuracy comparable to a premium, cost-prohibitive factory INS, all while utilising the low SWaP-C footprint of the ISS360.

Real-world validation of the ISS360 SLAM pipeline was conducted at the WHOI Iselin Pier.

Divers guided the ISS360-equipped REMUS-100 through consecutive laps at a depth of 10 meters, navigating around a dense grid of underwater support pilings.

The environment featured low visibility (under 2 meters) and active tidal currents.

The ISS360 delivered exceptional acoustic clarity, achieving extraordinary benchmarks across more than an hour of continuous submerged deployment:

• 90%+ Error Reduction: Across the mission, the average absolute position error was bound to a mere 3.4 meters, successfully arresting compounding dead reckoning drift.

• Flawless Full AUV SLAM navigation: Operating without a pre-existing map, the system recorded a nearly identical average error of 3.3 meters.

• INS Parity: The 3.3-meter average error achieved purely through the ISS360 SLAM pipeline is comparable to the expected accuracy of an expensive, heavy, factory-grade INS navigating the same course.

The MIT-WHOI study successfully demonstrates that subsea operators do not need to sacrifice size, power, or budget to achieve pinpoint, drift-free autonomous navigation. The Impact Subsea ISS360 Scanning Imaging Sonar delivers commercial and defense operators a high-fidelity, ultra-compact acoustic imaging solution that serves dual purposes.

Beyond delivering crisp 360° environmental visualisation, its rich data output enables modern edge computing architectures to execute real-time localisation and mapping.

By choosing the ISS360, AUV manufacturers and service providers can unlock AUV SLAM navigation tracking and advanced structural autonomy at a fraction of the SWaP-C of traditional inertial sensors.

Further Resources:

• Read Andrew J. Motz’s thesis: SLAM for Structured Environments Using Mechanically Scanned Imaging Sonar
• Learn more about the ISS360 Imaging Sonar
• View the full Case Study

 
This week the team spent a productive day at Capernwray Diving Centre in Lancashire, England, putting the ISS360 sonar series through its paces. 

By deploying our range of high performance imaging sonars from pole mounts, tripods and a Blueye Robotics ROV allows us to test the performance in a range of deployment scenarios. 
 
It’s one thing to talk about performance; it’s another to see it mapping underwater wrecks in real-time. 
 
A successful trip with even better results. Check out some highlights from the day! 

Here’s Capernwray Diving Centre Website: https://www.dive-site.co.uk/

Looking forward, Impact Subsea continues to invest in the long-term development of the ISS360 and ISS360HD Sonar.  Further new developments in the ISS360 range are expected to be released later in 2026.  

[Explore the ISS360 Series] | [Access the SDK on GitHub] |

[ISS360 YouTube Playlist] |

Impact Subsea is proud to highlight the continuous development and global success of the ISS360 Imaging Sonar series.   

Since its groundbreaking debut in 2020, the ISS360 has evolved into the industry’s premier solution for Subsea Imaging on ROV and AUV for navigation and target identification, offering a modern, high-performance replacement for legacy, scanning sonar systems. 

A Five-Year Journey of Technical Excellence 

Launched in March 2020 as the world’s smallest scanning, imaging sonar, the ISS360 was designed to provide a step-change in capability for the underwater vehicle market.  

The ISS360 Imaging Sonar has undergone development, evolving from the world’s most compact, scanning sonar into a high-definition powerhouse that outperforms systems many times its size. 

Over the past five years, Impact Subsea has maintained a rigorous development roadmap to meet the increasing demands of the subsea industry: 

• 2020: The Foundation: Introduced resilient operation via inductive coupling, entirely removing the need for slip rings, a common failure point in traditional scanning sonars. 

• 2021: Extreme Depth: Launched the 6,000-meter rated ISS360, featuring a Titanium housing and specialized pressure-compensated components for ultra-deepwater missions. 

• 2022: High-Definition Clarity: The launch of the ISS360HD brought a 1° acoustic angular resolution and a 2.5mm range resolution, enabling operators to identify targets in zero-visibility conditions with unprecedented detail. 

• 2023: Seamless Integration: Direct GitHub access to an Open-Source Software Development Kit (SDK), allowing AUV developers to integrate the sonar directly into bespoke software packages. 

• 2024: Released Impact Subsea Signalling Scheme (IS³): To reduce interference between sonars operating in close proximity to each other.  This advanced signalling scheme makes use of CHIRP combined with Phase Shift modulation and coding.  

• 2024: Released the ISP360: Expanding the sonar range with a profiling sonar option. 

Seamless Integration: Open-Source SDK 

Impact Subsea believes in empowering users to push the boundaries of subsea autonomy. To facilitate this, the company provides a free, open-source Software Development Kit (SDK) for direct integration. This operating-system-independent library, available via GitHub, has allowed AUV developers and manufacturers to integrate the ISS360 sonar directly into bespoke software packages, enabling custom interfaces and advanced vehicle autonomy. 

The Ideal Upgrade for Legacy Systems 

If your operations relied on recently discontinued compact scanning sonar lines, the ISS360 offers a superior path forward. It was designed from the ground up to exceed legacy sonar performance in every metric. 

While the ISS360 represents the cutting edge of sonar development, Impact Subsea understands that reliability is built on support. The company is dedicated to providing long-term availability and comprehensive technical support for the ISS360 range.  

To ensure peak performance throughout the life of the sensor, Impact Subsea offers professional servicing to maintain seal integrity, O-rings and calibration. 

Proven Performance for Subsea Imaging 

The ISS360 has earned “performance wins” in some of the most challenging subsea environments. Notable achievements include: 

• High-Value Recovery: Guiding a Mohawk ROV to recover over $1 million in lost oceanographic equipment in near-zero visibility. 

• Scientific Autonomy: Integration into the Woods Hole Oceanographic Institution (WHOI) REMUS AUVs for advanced obstacle avoidance. 

• Infrastructure Lead: Trusted by Bay Dynamics for high-precision reservoir inspections. 

• Cable Touchdown Monitoring: Integrated with North Sea Systems’ innovative CableFish® system. 

“The ISS360 was designed to be a step-change in the miniature sonar market,” says Ben Grant, Managing Director, Impact Subsea. “Advanced acoustics enable excellent image clarity and by eliminating slip rings and utilising Titanium as standard, we provide a more physically resilient sonar. When combined with our expert service and support, the ISS360 offers a level of longevity and performance that was previously unavailable in a sonar of this size.” 

Looking forward, Impact Subsea continues to invest in the long-term development of the ISS360 and ISP360 Sonar range.  Further new developments in the ISS360 range are expected to be released later in 2026.  

Ready to upgrade your underwater vision? 

[Explore the ISS360 Series] | [Access the SDK on GitHub] | [ISS360 YouTube Playlist] 

Impact Subsea, today shared the results of a study comparing the performance of its ISS360 and ISS360HD imaging sonars for Autonomous Underwater Vehicle (AUV) obstacle avoidance.

The study, conducted by researchers at the Massachusetts Institute of Technology (MIT) and Woods Hole Oceanographic Institute, was presented at the IEEE AUV Symposium in Boston.

Led by Andrew Motz, Nathan McGuire and Jeff Kaeli, the study evaluated the two sonar systems under various underwater conditions, including different ranges and target types. The researchers compared the sonars’ signal-to-noise ratio (SNR), average target strength, average noise level, overall average intensity and level of sensor saturation.

The results were clear: the ISS360HD demonstrated superior performance in all categories, particularly in terms of SNR, which is crucial for detecting obstacles at longer ranges and in challenging underwater environments.

This improved performance is due to the increased angular resolution of the ISS360HD, which enables the ISS360HD to capture more detailed and accurate information about the surrounding environment.

Ben Grant, Managing Director, Impact Subsea said;

“With the ISS360HD sonar we were keen to provide high resolution sonar imagery to all classes of underwater ROV and AUV. We are pleased to review the exciting work of MIT and WHOI and their thoughts on the ISS360HD benefits for future AUV integrations.” 

The study’s findings have important implications for the marine technology industry, as AUVs are increasingly being used for a wide range of applications, including scientific research, offshore exploration and environmental monitoring.

The ISS360HD’s superior obstacle avoidance capabilities can help to ensure the safety and reliability of AUV operations while also improving their efficiency and effectiveness.

The ISS360HD sonar page

Comparing Sonar Suitability for AUV Obstacle Avoidance Poster

A previously published paper focused on using Impact Subsea sonars within AUVs as part of an automated obstacle avoidance system. Using the ISS360 sonar with the Remus 100 AUV.

The subsea world can be a murky place, making it challenging to monitor crucial operations like cable deployment. This is where the ISS360HD Imaging Sonar comes in, recently integrated with North Sea Systems’ innovative CableFish® system. This powerful combination enables accurate visualisation and real-time monitoring of cable touchdown points during deployment.

Unveiling the Invisible: Benefits of ISS360HD

The ISS360HD goes beyond traditional methods by providing a continuous clear visual image of the cable throughout deployment. This is especially valuable in zero-visibility conditions where cameras are not an option.

Key features:

• High-resolution imaging: Provides a detailed view of the cable and surrounding environment.
• All-weather performance: Operates effectively regardless of visibility.
• Side-on view: Achieved by vertically deploying the ISS360HD offering a unique perspective on the operation.

CableFish®: Revolutionising Subsea Cable Touchdown

The CableFish® system leverages the power of the ISS360HD, combined with the ISA500 Altimeter and ISD4000 Depth Sensor, to enable faster and more precise subsea cable installations. These additional sensors provide critical data for accurate cable deployment and positioning.

Key benefits of CableFish®:

• Effective in challenging environments: Handles shallow waters and high currents where traditional Remotely Operated Vehicles (ROVs) struggle.
• Continuous monitoring: Provides real-time data for informed decision-making throughout deployment.
• Automated operation: Automatically maintains a set altitude above the seabed, providing consistent monitoring with minimal personnel requirements and therefore significant cost savings.

Embrace Efficiency and Accuracy with This Cutting-Edge Solution

The integration of ISS360HD, ISA500 Altimeter and ISD4000 Depth Sensor with CableFish® represents a significant advancement in subsea cable installation. It offers unmatched efficiency, precision and real-time data for a smoother and more successful operation.

Further Resources:

• Learn more about the ISS360HD Imaging Sonar
• Discover the CableFish® system

Impact Subsea has provided several ISS360HD Sonars to Seatronics, a brand in Acteon’s Data and Robotics Division.

The ISS360HD Imaging Sonar provides a step change in performance in the scanning imaging sonar market. Providing a 2.5mm range resolution combined with a 1° angular resolution enables exceptionally high definition imagery from a highly compact sonar.  With a range capability in excess of 100 meters the ISS360HD can suit a range of AUV, ROV and standalone underwater applications. 

Richard Main, Regional Manager UK Seatronics commented

“We have a focus to provide the best in class technology to the subsea industry. Having added ISS360 sonars earlier in the year to our rental pool we are delighted to now also add the ISS360HD.  The ISS360HD will provide our customers with high resolution sonar imagery for large work class vehicles as well as observation class vehicles”.

Ben Grant, Managing Director, Impact Subsea commented

“We have worked with Seatronics for many years and with the addition of the ISS360HD; now all Impact Subsea sensors can be hired from Seatronics.  We have seen a high demand for the ISS360HD since launch and are delighted to continue to work with Seatronics to support that demand”.

To learn more about Seatronic’s ISS360 & ISS360HD rental solutions please click here.

To learn more about the ISS360 range of sonars please click here.

Impact Subsea has announced a new addition to the ISS360 Sonar range – the ISS360HD.

The ISS360HD offers a 1° acoustic angular resolution, 2.5mm range resolution and a distance measurement range in excess of 100 meters/328 feet.  The sonar is depth rated to 6,000 meters / 19,685 feet and comes in a very compact form factor.

The ISS360HD has a very wide operational acoustic bandwidth capability; 600 to 900kHz which is fully utilised through CHIRP (Compressed High Intensity Radar Pulse) technology.  The wide bandwidth CHIRP allows for an excellent range resolution of 2.5mm when using the full bandwidth. 

A narrow acoustic beam, combined with a very short range resolution allows for extremely high definition imagery to be produced.  This makes the ISS360HD ideal for work class ROV operations with excellent range capability and ability to identify targets in zero visibility.  The form factor of the sonar also opens this capability up to even the smallest of observation class ROVs.

Below is example imagery from the ISS360HD. Image shows harbour wall, harbour floor with wheels, rope, stones etc. Also shown is the shoreline (left) and boat mooring rope on the water surface.

In addition to the long range and high resolution capabilities, the ISS360HD benefits from an inductively coupled transducer.  This means there are no slip rings within the sonar – so there are no components to wear out and require periodic replacement. 

The sonar optionally comes with an integrated pitch and roll sensor, allowing accurate attitude readings to be provided.  This is a very useful capability when deploying the sonar using a tripod to ensure level positioning. The integrated pitch and roll sensor is also a useful additional sensor reading for some underwater vehicles.

In terms of connectivity, the ISS360HD benefits from serial (RS232 and RS485) and also ethernet communications.  When using ethernet communications, the sonar has been found to scan up to six times faster than other, competing serial only based sonars. This provides a significant benefit when using the sonar for underwater vehicle obstacle avoidance purposes.

The ISS360HD operates with the Impact Subsea seaView V3 software, allowing seamless use alongside the Impact Subsea Altimeter, Depth Sensor, AHRS sensor and FMD system.

For those wishing to use the ISS360HD sonar with an autonomous underwater vehicle, a Software Development Kit is freely available to allow direct integration of the sonar.

To learn more about the ISS360HD please click: here

Watch our Introduction film on YouTube: here