Underwater Pit Stops

ASSY REMUS 600 VEHICLE WITH HOVERING MODULES

Autonomous underwater vehicles and surface vessels are currently the subject of a great deal of research effort. It is widely predicted that future anti-submarine operations will include surface and sub-surface unmanned systems, some deployed from submarines, some from surface ships. In common with all visions of the future, significant technical and engineering challenges remain.

Control software and sensors are increasingly sophisticated, but the underwater environment is extremely challenging for power and communications. For high endurance systems, solar power is unavailable and communications at range is excruciatingly slow. Whilst science and engineering will no doubt continue to increase stored power densities and develop cutting edge underwater communications systems none of them are likely to offer tangible and practical solutions in the near term.

The US Navy Office of Naval Research has approached the issues of power for sustained underwater operations and high bandwidth communications in a novel manner.

Underwater recharging and communications stations.

The project is called Forward-Deployed Energy and Communications Outpost, or FDECO.  It actually doesn’t start until next year but I think it will be a critical element on the roadmap to creating underwater networks of manned and unmanned submersibles.

Their objective is to create an underwater docking station that allows autonomous underwater vehicles to dock, upload the large amount of data it might have collected at high speed and recharge the batteries.

When charging and data upload are complete, it will receive new orders and be on its merry way, without human intervention and all carried out underwater.

The docking station will then transmit that data to manned submarines, control centres on land or nearby ships using a combination of low-frequency radio, a rising satellite or WiFi communications buoy, or potentially, conventional fibre optic cables.

Power for battery recharging will be provided by fuel cells and in some situations, supplied from land.

The docking stations will enable a network of autonomous underwater vehicles to operate on a persistent basis.

There are a number of interesting operational uses, a number of docking stations could be placed in international waters and used to establish and maintain relatively low risk underwater situational awareness of a target port, choke point or coastal area. They could be used in a defensive manner or simply established against some future contingency.

Tethering them to land using power/communication cables or to wave power generating buoys might not be especially ‘stealthy’ but this might not necessarily be a significant issue in some situations. Use enough of them and by virtue of their numbers, the system as a whole becomes highly resilient.

Using vessels of opportunity for launch and recovery and communications relays decreases the chances of enemy detection.

Make them less obvious by using an ISO container format and deployment might simply be a case of throwing them off the back of a convenient ship. (you knew I was going to say that, didn’t you!)

Perhaps the most significant challenge the project faces is a rather mundane one, making sure the docking station has the right plugs and sockets for the AUV’s. Every manufacturer has their own power and data interfaces. FDECO will aim to reduce the amount that each vehicle will need to be modified but each AUV will need to be modified nonetheless.

A more effective long-term solution would be standardisation, made possible by standards such as the UK’s Generic Vehicle Architecture. Extend this to AUV’s and adaption for each vehicle should be eliminated.

It is also interesting that the idea is not wholly new

There have been a number of experiments, trials and deployments with single manufacturer systems and a couple of projects currently in progress. What characterises these other projects is that they are tethered, taking their power and communications feeds from the shore via cables or using moored buoys.

In 2011, the Woods Hole Oceanographic Institution (WHOI) contracted Kongsberg/Hydroid to create an underwater docking station for a REMUS 600 AUV as part of the Ocean Observatories Initiative (OOI). The Pioneer Array uses three electromechanical surface moorings, each having solar and fuel cell power generation, satellite communications and a number of sensors. At the mooring point for each of the buoys is a multi-function node that supports an AUV dock and additional instrumentation.

Pioneer Array

Kongsberg AUV Docking

NavLab_-_a_short_introduction_-_AUVs_in_Extreme_Environments_G_Lester_Kongsberg_Maritime.pdf_-_2015-07-11_19.05.53

The Monteray Bay Aquarium Research Institute (MBARI) created a similar underwater instrument cluster with docking stations for AUV’s.

MBARI Docking

Bluefin Robotics and Battelle have created a similar underwater docking solution, although arguably more sophisticated.

One of their proposed configurations includes carriage of the docking station inside an SSGN missile silo.

Battelle Docking Station 1

Battelle Docking Station 2

Battelle Docking Station 3

Not to be completely outdone, Europe had EURODOCKER, a much older project funded by the European Commission that examined similar problems of docking, power and data transfer but using a cage suspended from a vessel.

Eurodocker 1

Eurodocker 3

Eurodocker 2

Much of the technology already exists.

The challenge for FDECO, and whatever other systems are developed elsewhere, will be integration and developing the operational concepts.

An interesting future of underwater networks, autonomous underwater vehicles and manned submarines awaits.

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