Keeping an eye on below-the-waterline assets
New technology is giving port operators the ability to see what's going on under the surface, even in murky or inaccessible corners, writes Stevie Knight.
The unaided human eye isn't up to it anymore. Routine subsea checks “can be slow and costly and often include manual visual inspections with a large margin of error”, according to Rick Hunter, Avitas Systems. According to him, underwater drones equipped with enhanced imaging are the answer in ports.
In fact, there are so many areas suitable for drone inspection underwater that it's hard to know where to begin. They cover everything from surveying structures, cables and pipes, along with keeping track of debris and vegetation growth to port floor mapping and channel clearance. “We've been used on naval operations, hull inspections, explosives and broken piers,” says Blair Cunningham of Coda Octopus.
Importantly, the technology can also be used to assess damage from storms or floods, locate sunken debris and provide a map of critical infrastructure and fairways quickly enough to get the port working again. “These systems are increasingly being used to manage a port's complete underwater environment,” he says, adding there are 'side' benefits such as security and water analysis.
Normally you need skilled technicians on a dedicated survey vessel for inspecting assets below the surface, but Coda Octopus claims to have taken “the black art out of the process” with systems that can be mobilised “in under an hour”.
Some platforms are now being designed to be light enough for deployment on Autonomous Underwater Vessels (AUVs). Unlike their tethered, heavier remotely-operated vessel cousins, AUVs can be limited when it comes to sending back high definition video to the operators – and the water is often too murky for cameras to be reliable. Sonar, therefore, is much more useful as it can outline even partially buried assets.
However, the returning data can be hard to translate. “Given this, you usually can't see much in front. It's like driving using parking sensors, you just get a blip on the screen,” says Mr Cunningham. “Our technology fuses sensor information to provide a three-dimensional, volumetric image – that means you can instantly see subsea structures live, without any post-processing. As you can be the eyes onboard, it can be directed real-time, that's the key thing. Operators can move it around to look at whatever they want.
He adds that it can investigate structures and the returning information is delivered on photograph-like images which have enough definition to spot spalling, small concrete cracks that indicate early signs of failure. But the system's really a Swiss Army knife: a utility platform that you can tune to specific operations. “So, by adjusting the sensors to a different frequency we could get it to see internal damage in metal,” says Mr Cunningham. All the 3D sonar and camera data is stored together in a GIS database which allows for an easy comparison from one scan to the next.
Where it really gets interesting is where new technologies converge. Take Avitas' technology: this mounts Kraken Robotics' 3D sonar, camera and laser scanner on an AUV or ROV. Interestingly, the scanner generates a detailed 'cloud point' map that it then colours in, characterising corrosion, cracks, marine growth and so on for easy visualisation. But, most importantly, Avitas' system provides completely autonomous inspection that can follow precise swim paths, says Mr Hunter.
These underwater craft are far from just blindly taking a pre-set route as they will also be able to guide their own inspections.
Both sonar and navigation software allow the craft to track certain elements and identify priority areas. Furthermore, Mr Hunter explains that “the paths' repeatability enables artificial intelligence-based change detection and automated defect recognition”. The multiple streams of sensor data are fused together and image analytics then works on predictions; so in short, these units can 'learn' what to look for, go back and check it out. Mr Hunter says this gives you “smarter inspection scheduling based on anticipated risk”.
However, these developers aren't alone and new entrants are intent on pulling the investment bar down: BGN Technologies in Israel has developed the HydroCamel II AUV at a competitive price while other, cost-effective underwater inspection devices take a 'toolkit' approach.
For example, Indian Planys Technologies’ 'Beluga' is a light work ROV that comes down on the side of endurance rather than distance. Because it keeps its tether and retains an external electrical source, it has power rather than sylphlike weight so, along with sonar, cathodic protection and ultrasound thickness measurements, it can even take on spot cleaning of moderate biofouling.
However, port assets usually sit in the shallow end and so there’s a growing demand for Unmanned Surface Vessels (USVs) tailored to a variety of applications, especially as USVs can handle considerable payloads. Peel Ports, for example, has recently started exploring what ASV Global’s C-Cat3 can do for restricted water surveys, beginning with a dock on the UK’s Mersey. Likewise, the Port of Rotterdam is rapidly developing its own technology stream for difficult to reach areas including a 1 metre USV that is small enough to slip under jetties and can look down below the waterline as well as upward, scanning the surfaces inside the structure.
Moving from manual inspections
Once again, artificial intelligence may soon be edging its way into developments. While many of these USVs can be operated remotely or work their way along a predetermined path, there’s a trend toward collision avoidance and from there, AI autonomy doesn’t seem such a huge step. That’s not the only driver: Rotterdam’s USV produces high-quality pictures in their hundreds, says Mr Voogt, “and that’s the problem... inspectors don’t have the time to look through them all”. Tracking a crack that’s developed between one picture and another “is a process best automated”, he says.
As part of its Smart Infrastructure programme, Rotterdam's big quay projects are now regularly fitted with sensors, explains the port’s asset manager Henk Voogt. “A high groundwater level behind the quay at low tide can result in an extreme load case, so we've been using simple groundwater sensors for quite a while.” He adds that more sophisticated embedded sensors can watch out for a 'piping effect' “which means you are losing soil”. The answer is adding glass fibre lines which will detect earth movement hidden behind the quay.
There are also sensors that keep an eye on the active cathodic protection of the piling, monitoring the amount of current needed to protect the metal. “That gives us information about the present state of affairs – and a lot of information about how to optimise our piling design in future,” says Mr Voogt.
These systems already have their adherents, and some, like Coda Octopus, are well-established with fans in ports such as New York and Los Angeles. Sergeant Steve Smock of the Long Beach Police Department describes it as “a game changer”, adding that the high-resolution images “allow us to identify changes in our ports by comparing previous surveys with the latest survey”. Immediate information, he says, avoids “wasting time and money”.
SMART FUTURE FOR UNDERWATER SOLUTIONS
Underwater technology has already developed far enough to boost a very broad swathe of operations. For example, 3D, volumetric imaging sonar can reach well beyond monitoring established assets.
Coda Octopus’ Blair Cunningham explains: “People still generally rely on 'old-school' information gathering for dredging; they take the information from a survey done previously, then they dig and dig blindfold, check it, and then go back and dig again.” But now he says: “You can carry out dredging operations with real-time imaging telling you exactly what you are doing – while you are doing it.”
Then there's the 'pollution sniffing'; present technology is able to keep track of water quality and could even help identify offending ships.
The area is developing very fast, says Avitas Systems’ Rick Hunter, with media-video and real-time 3D colour models becoming easily available; he expects the advances in machine learning, computer processing speeds and edge computing to combine “and contribute to more advanced, efficient, and safer subsea inspection”.
Of course, lower cost sensors are at the base of the technology pyramid. The Port of Rotterdam’s Henk Voogt points out that “the automotive sector has driven up capability and driven down costs until we can use the kinds of sensors produced for cars directly on our assets”.
In other words, sensors have become cheap and flexible – so expect more ports to start building 'smart' structures of their own.
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