As more equipment goes on the seafloor, the industry is increasing its hunt for permanent underwater robotics solutions. Elaine Maslin got a view from Kongsberg Maritime.
This year, two of Kongsberg Maritime subsidiary Hydroid’s REMUS 600 autonomous underwater vehicles(AUV) will be deployed off the coast of New England, North America.
They will be carrying out subsea scientific research as part of the Pioneer Array project, Ocean Observatory Initiative (OOI) scheme, which aims to understand the interplay of physical and biological processes.
What marks out the project is that the AUVs will spend up to three months at a time in the ocean before being brought out of the water.
The limitations of remotely operated vehicles (ROVs), which have to be accompanied by the vessels they are tethered to, and AUVs are being challenged, says Richard Mills area sales manager for AUVs, Subsea Division, Kongsberg Maritime.
“The AUV industry and some of the existing players in the ROV industry have the capability to build this type of vehicle for prolonged deployment in the ocean at or near an oil facility,” he said.
But, he adds: “There are some hurdles to overcome though: infrastructure, energy, and operator confidence to name a few.”
This equipment area has already seen several developments toward the resident AUV, with projects including the Swimmer, being developed by Cybernetix in partnership with Total, and more recently the Saab Sabretooth, an ROV/AUV hybrid.
Currently leading the field are probably the scientific and academic communities, said Mills. Hydroid’s two REMUS 600s are being sent, along with two subsea docks for resident deployment.
The concept for the OOI application is that the two REMUS AUVs are positioned with one at each dock. They are released at the same time and swim to the other dock, and then are resident for up to 120 days.
The REMUS 600 is a mature vehicle with proven, good reliability, and predictable repeatable behavior, essential criteria for long term deployments, said Mills. “The docks are relatively simple mechanical devices, with a location device to enable the AUV to ‘home’ to it,” he said. “Once close enough, it is fed into a funnel where it latches into the dock.”
Through a surface buoy with solar power generator and remote communications link, it can then recharge and transmit mission payload data to be sent to the operating base.
“This is perhaps where the scientific community has the upper hand,” said Mills. “The ability to implement unique solutions is easier to justify. In the oil industry, power and data would have to be routed via subsea structures and cables. These are difficult to get implemented in existing fields and more suited to new developments.” Mills think s a truly autonomous solution for the commercial sector is feasible today—but provided the vehicle’s tasks are realistic.
“As of today, processing power enables a number of inspection tasks to be conducted without an operator,” he said. “Any interaction with structures requires a level of processing not yet demonstrated sufficiently to give the operators enough confidence to do away with the tether. Hence Swimmer has an onboard ROV with tether, or the fiber-optic, detachable tether of other systems.” There are some new technologies coming forward that may enabling control without a tether, and the arrival of high bandwidth, high-speed, reliable underwater communications is now starting to happen. However, current systems still have very short-range capabilities and would still require some level of installation on existing structures that could prove expensive, he said. “Finally, the confidence and preferences of the operators are potentially more challenging than the technology,” said Mills.