Can ROVs Go Wireless?

Today’s underwater robotic technology is firmly divided into two distinct product segments: Remotely Operated Vehicles (ROVs) and Autonomous Underwater Vehicles (AUVs).

The key difference between the two is whether there is a human in the loop or not.

AUVs are travelling underwater on a fully pre-programmed mission. Generally, these are torpedo-shaped vehicles that cannot hover and are carrying a sensor payload which is collecting data along the way. There is a new trend emerging in large intervention AUVs from the likes of Oceaneering, Saipem, Saab, and Nauticus. These are much more complex robotic systems with an array of sensors and manipulators, although their full autonomy capabilities are still being developed. Naturally, an AUV is a fully detached vehicle and relies on on-board intelligence to complete a mission. This means that a pilot cannot have immediate access to the AUV to control it.

ROVs, on the other hand, typically always have a human in the loop. And both are connected to each other through a tether—a physical cable carrying data and sometimes power. This allows for immediate control of the vehicle, but it carries a number of disadvantages. Firstly, as the tether gets ever longer to follow the ROV, it increasingly creates more drag and requires the ROV to spend additional energy to pull it. Secondly, tethers restrict the maneuverability of an ROV, especially the thicker kind of tethers which also carry power. Finally, a tether is an entanglement risk. In complex underwater environments, tether management becomes challenging and can significantly slow down the inspection process.

THE SPEED OF LIGHT

While power demand can be addressed with internal batteries, exchanging data wirelessly through water is harder to achieve. Radio waves don’t work underwater, and the data rate of acoustic communication is low. The only option is to use light. And this is what a Swiss-based underwater robotics company Hydromea did. They developed a proprietary high-bandwidth wireless communication system they call LUMA. LUMA uses blue or UV light to wirelessly exchange data with low latency and at high bandwidth. LUMA devices are already being used in several subsea applications for short-range wireless communication, such as data harvesting from sensors and wireless data exchange between ROVs and other subsea infrastructure.

GOING WIRELESS

When it comes to de-tethering an ROV, LUMA enables fast wireless connectivity between an ROV pilot and the ROV.

Within a range of 30 – 50 meters, in reasonably clear waters, the pilot can remotely control the vehicle and get instant HD video feedback just like aerial drones do in the air—wirelessly.

Hydromea calls this new ROV system EXRAY and claims it to be the world’s first portable wireless ROV. Today EXRAY is already performing limited inspections on assets in the North Sea and is scheduled to be unveiled for full commercial availability at SPE Offshore Europe in Scotland in September. The EXRAY system has just received a class certification from DNV for inspections of ballast water tanks on Floating Production Storage and Offloading (FPSO) platforms in the offshore oil & gas industry.

LEARNING TO FLY

So how exactly does the EXRAY system work? EXRAY has two slim ROVs docked to each other. One ROV is tethered to the pilot station and the second ROV (a flyout) is docked to the first one. As long as these two are connected, the system behaves as one ROV. The pilot can switch between control of the ROV and the flyout instantly with a single switch.

The pilot always has camera feeds from both vehicles which is an added benefit as it provides much better global awareness for the pilot. With the tethered ROV holding position, the pilot can fly the flyout around pipes, anodes, staircases and other submerged furniture—all without any concern of tether entanglement and all the while receiving full-HD video feedback, having the possibility to take 4K images—even in a macro mode, measuring metal thickness using a fully integrated Ultrasonic Thickness (UT) probe which provides a live A-scan to instantly verify the thickness reading. The pilot can move both vehicles independently while they are not docked. Once the inspection is finished, the pilot docks the flyout into the tethered ROV and it is one system again.

EXRAY is extremely slim and easy to control in all orientations thanks to its 6 degrees of freedom. 4 hours of battery life is ample time for the pilot to finish a job that would usually take 8 hours or more. While the initial focus is on confined space inspections with relatively clear water, such as water and storage tanks, industrial water basins, hydropower installations and nuclear pools, the next frontier are open water environments with limited visibility where Hydromea intends to further exploit the best of both worlds between a traditional ROV and a traditional AUV.

SUCCESS IN THE FIELD

What is the real benefit of having a wireless flyout system like that? Hydromea’s first service partner in the North Sea, Air Control Entech (ACE), has been using the system since the beginning of 2023 on several inspection jobs. Kieran Hope, ACE’s COO, says about the system: “EXRAY is an intuitive and flexible system that our pilots quickly got a handle on, and they are excited to perform inspections jobs with it. Not only is it easy to work with, but the system also significantly cuts the time it takes to inspect an asset. From our initial experience, we are already 50% more efficient with this system than what we were with a traditional ROV.”

He adds: “The tethered ROV itself is already a top-of-the-line vehicle that can do more than most other ROVs. And coupled with a flyout, EXRAY is an exceptional piece of kit that is redefining the underwater inspection market. From the intuitive controls to the autonomous features to the data management, this system puts most other players to shame. We have an increasing demand for class inspections with this system from the operators and we clearly feel that we are setting a new standard in the inspection market together with Hydromea.”

This story was originally featured in ON&T Magazine's June 2023 issue. Click here to read more.