Bigger Brains, Better Batteries Will Enable New Missions For Robotic Submarines
As the Navy takes on a larger role in national security strategy following the conclusion of two land wars, unmanned underwater vehicles may have another shot at becoming a technology favored in future budgets.
“There’s not a lot of money in underwater robots compared to unmanned aerial vehicles,” Chris Mailey, vice president of knowledge resources at the Association for Unmanned Vehicle Systems International, told National Defense. “Globally, spending on maritime robots is about 8 percent of what is spent on unmanned aerial systems.”
The Defense Department budgeted a little more than $1 billion for all unmanned maritime systems in fiscal year 2014, about half of which is aimed at procurement and development of underwater vehicles. The Pentagon plans to spend more than $5 billion on pilotless aircraft next fiscal year, according to AUVSI figures.
The six UUV programs of record — those that are being purchased and fielded — will be allocated a total of $88 million in fiscal 2014.
A major factor in the disparity between flying and underwater drones is that the U.S. military — a pioneer of unmanned technologies — has been fighting in landlocked nations over the past 12 years. UAVs and bomb-disposing ground robots gained all the glory in those conflicts, Mailey said.
So-called “gliding” submarines that use buoyancy instead of engines for propulsion cost about $100,000 apiece — a bargain compared to their multi-million-dollar flying counterparts that cannot see beneath the waves. A heavy reliance on commercially available technologies has driven the cost of UUV development and procurement down as well, he said. Most small and medium-sized robotic subs cost less than $1 million.
UUVs were capable of gathering intelligence and performing mapping functions in the early 1990s, but have faced budgetary and fiscal hurdles in the following years. Development of underwater robots has been aimed almost solely at explosives disposal. Any funding to build robots for other maritime missions has had to compete with larger legacy procurement programs, Mailey said.
“There hasn’t been much evolution in the technologies since then,” he said. “There has only been so much money to go around. Anything outside mine countermeasures is competing with other programs like the Ohio-class replacement submarines.
“If you’re competing with something like that, are a bunch of submariners going to go with a new, untested robot or something that is tried and true that we absolutely need? Because of that paradigm, the funding for UUVs has always disappeared.”
Funding has reappeared in the Navy’s fiscal year 2014 budget request for a slew of UUV projects at the service’s labs and at the Defense Advanced Research Projects Agency. The Navy has requested $350 million for research and development of UUV technologies.
A primary area for UUV research is how to power them, said Alan Beam, a retired Navy captain and former program manager for unmanned underwater vehicles at DARPA. Beam now runs the Autonomous Undersea Vehicle Application Center, which advocates for the development and integration of UUVs in both the defense and commercial sectors.
A robotic submarine’s power source directly affects its size and range, he said. The same is true in reverse.
“Power goes with volume,” Beam said. “It’s always a tradeoff. If you go from a 21-inch diameter vehicle to a 26-inch vehicle, you can put four times as much power in it and thus give it many more times the range.”
Range is important in information gathering missions, for which UUVs are being tested. They must roam the deep ocean over long distances and for long periods to collect data for missions like mapping, mine hunting and surveillance of other vessels.
The Navy’s UUV roadmap calls for improvements to underwater surveillance not only for traditional situational awareness missions, but also as a “precursor to future capabilities like finding enemy submarines and more effective mine disposal.” The document, which outlines the intended future of UUV technology, has been classified since 2004. Robotic submarines allow sailors to perform many missions currently done by manned ships, without exposing sailors and expensive vessels to potential threats — essentially the same benefits UAVs provide to the Air Force.
They have the added benefit of multiplying the number of eyes a fleet has scoping a contested area, providing long-endurance situational awareness at all times when a manned vessel is underway.
Future roles for robotic submarines include patrolling harbors for threats to ships and infrastructure, hull inspections and route clearance for ships while underway. All of these missions require the long-endurance capability that has so far eluded UUV engineers.
“The requirement for long endurance is difficult but not impossible to achieve when choosing from today’s energy source technologies,” the Navy’s roadmap says. “Long-range communication, though not always required, is an issue. Improvements in current UUV communication capabilities are required. In particular, there is a strong need to increase the bandwidth of communications links while reducing their vulnerability to be intercepted.”
That type of mission requires unmanned vehicles with long endurance that will not need to return to ship or shore to refuel or receive commands, Beam said.
A big player in extending the range and endurance of unmanned underwater vehicles is the Office of Naval Research, which Beam said is pioneering maritime battery technologies that will be smaller, yet more powerful, than existing fuel cells.
A spokesman for ONR declined to comment on ongoing projects, saying that most of the laboratory’s UUV research is classified. ONR is planning to make a “major announcement” of UUV technological innovation in the spring, he said.
Another challenge engineers have had to overcome is the general reliability of current systems. Small underwater vehicles can only be relied upon to perform short-endurance missions with limited objectives.
“Large or small, there is a need for vehicles that can be trusted to stay out for long periods of time — maybe months — and be able to recognize new missions and faults with their own systems,” Beam said. “We need systems that can look at the mission, then themselves, and say ‘I can’t do this one. I need repair. I’m coming back to base.’”
The Navy wants systems “capable of detecting, recognizing and avoiding threats of a varied and mobile nature,” the service’s roadmap reads. “Object avoidance requires a high degree of autonomy, both in threat recognition and the determination of the best means of avoidance. As capabilities improve and the threat evolves, continued enhancements will be required.”
Such a level of autonomy requires the same scarce resource within the UUV as reliability and power: space inside the vehicle’s hull. Engineers have been developing autonomous robotics technology for decades, but the sophistication of a UUV’s brain is dependent on how much computing power is aboard.
In the early days of UUV development, computing power drove their size to diameters upwards of 45 inches, Beam said. As computers got smaller, so could the vehicles being designed for different missions — to the point where robots that perform intelligence, surveillance and reconnaissance missions can be hand-launched.
That trend has reversed recently as the size of UUVs increased to accommodate larger power sources that enable long endurance.
There are four classes of unmanned underwater vehicles recognized by the Navy. The man-portable class includes those from about 24 to 100 pounds, with an endurance of between 10 and 20 hours. There is no specific hull shape for this class, according to the Navy’s UUV roadmap.
Vehicles in the lightweight class are around 12 inches in diameter and weigh about 500 pounds. Payload is from six- to 12-times that of the man portable class and endurance is doubled.
The Navy has deployed the MK18 Kingfish UUV for operations with the Fifth Fleet around the Persian Gulf, following more than 30 sorties over two weeks of mock deployment testing in the Gulf of Mexico, the Navy announced June 20.
The program of record is funded at $14.4 million in the Navy’s fiscal year 2014 budget.
The Kingfish is designed for mine detection missions with an improved endurance and area coverage rate over the Swordfish that is currently deployed.
The Kingfish deployed May 6 near Panama City Beach, Fla., and launched from an 11-meter rigid hull inflatable boat. As many as four Kingfish were deployed at a time for eight-hour missions with no malfunctions, according to information from the Navy.
The Knifefish mine countermeasures UUV being fielded aboard the littoral combat ship also falls into this category.
Some of the most successful UUVs to date, called littoral battlespace sensors, are under contract for hundreds of units. Pocasset, Mass.-based Hydroid Inc. was recently awarded a contract worth $8.4 million for LBSs. The deal could expand to more than $77 million if the contract is extended to the planned 600 vehicles. The torpedo-shaped drones swim through shallow waters and provide data about ocean and weather conditions to the Naval Oceanographic Office, which then disseminates the information to Navy ships.
The heavyweight vehicle class includes submarine-compatible vehicles that are about two feet in diameter and weigh about 3,000 pounds. Capability is doubled from the lightweight class.
The large vehicle class is under development and will each weigh around 22,400 pounds. This class is the most promising of the developmental UUVs in the works, Mailey said.
ONR is testing what it calls the large-displacement UUV and is on the cusp of delivering it to the Navy as an “all-purpose truck” capable of carrying nearly any payload, he said.
“It’s meant to be pretty darn big,” Mailey said. “It is one of ONR’s top two UUV programs. Let your mind wander about having a truck that can run for months at a time.”
The Navy struck funding for the LDUUV from both the fiscal 2012 and 2013 budgets. Just under $150 million is scheduled for various research-and-development efforts on the vehicle, including hull and mechanical work, propulsion and anti-submarine warfare surveillance technologies.
Most of the funded vehicles are designed for intelligence, surveillance and reconnaissance missions; seafloor mapping; and anti-submarine warfare — all tasks that require powerful sensor payloads and communication capabilities. Mine countermeasure capabilities are the only offensive technologies the Navy is openly pursuing.
Looking out further, the Navy hopes to field UUVs that can deploy or retrieve payloads, gather, transmit, or act on information and engage targets in the water or on land.
Mailey believes UUVs have already, or soon will, prove themselves as technologies as worthy of attention and funding as their flying cousins.
“It’s different this time,” he said. “The vehicles that are out there have been hugely successful. Most are doing really dull, boring stuff, but they are out there and have raised the confidence that they have wide utility. We are finally where we want to be.”