The Navy plans to use unmanned surface vessels to patrol harbors and, when armed with missiles or a .50-caliber machine gun, to protect ships (Navy)
When a 33-foot unmanned boat fired six missiles and hit floating targets more than two miles away in October, Naval Sea Systems Command hailed it as “a U.S. Navy first.” They’d never before remotely fired long-range weapons from a seagoing drone.
The CIA and the Air Force have used armed UAVs for more than a decade; the Navy’s own aerial fleet includes the Fire Scout helicopter, the ScanEagle and the Broad Area Maritime Surveillance Demonstrator. But the water itself is a relatively new frontier for unmanned craft. The possibilities are endless, from minehunters to anti-submarine warfare to harbor patrol to maritime ISR. (The new acronyms are also endless, starting with USV, for unmanned surface vehicle; UUV, for unmanned underwater vehicle, and so on.)
“Unmanned systems are not a luxury; they are absolutely imperative to the future of our Navy,” Vice Adm. Kendall Card told a conference of unmanned maritime vehicle experts gathered in a hotel outside Washington, D.C., in February.
Yet, water-going robots bring unforeseen challenges — technological ones, to be sure, but also legal, regulatory and ethical tangles. Drones that fly or crawl on the ground are controlled by radio waves, but it is difficult — often impossible — to communicate with underwater vehicles. The answer, it seems, is autonomy — robots that are not remotely piloted, but that operate on their own.
“There are legal implications,” especially if the drones are armed, said Card, the director of naval intelligence and the chief of information dominance. “We are going to really have to think our way through this.”
If the Navy can’t communicate with its undersea drones, how will it know for sure where they are? Can human commanders be sure that a drone is aiming at the right target?
“Or are we just going to let it pull the trigger all by itself?” Card asked.
What if it destroys a fishing boat, a ferry or a cruise ship?
Or, he asked, what if a Navy drone “washes up on the beach. Who’s liable if it explodes” and kills people? And what if a robot vessel is caught operating in another country’s territorial waters — is that an act of war? Navy lawyers are busy researching what drone activities might constitute acts of aggression, Card said.
Whatever those Navy lawyers determine, underwater drones have already arrived. Today, the Navy owns about 450 unmanned underwater vehicles, according to Antoine Martin, an industry expert and principal of Unmanned Vehicle Systems Consulting. For the most part, they’re torpedo-shaped minehunting drones and free-swimming winged undersea gliders.
The minehunters are remote-controlled or semi-autonomous robots that are launched from manned ships and travel relatively short distances to search for mines. Among the Navy’s newly deployed minehunters are 4-foot-long SeaFox submersibles, which were rushed to the Persian Gulf last summer amid Iranian threats to close the Strait of Hormuz. Controlled via a fiber optic cable, they are armed with a television camera, a homing sonar and an explosive charge. Their job is to find mines and destroy them with the explosives. For the SeaFox, it’s a suicide mission, because they are more like remote-controlled swimming bombs than anything else.
A more sophisticated minehunter called Knifefish is under development. It’s an autonomous vehicle designed to swim away from a mothership, hunt for mines with synthetic aperture sonar, then swim back to the ship and report the location of the mines it has found. Divers or helicopters then would be dispatched to destroy the mines. Testing is to begin in 2015, with deployment possible in 2017.
A semi-autonomous surface-skimming drone, the Unmanned Influence Sweep System, is being developed to sweep minefields and trigger mines with acoustic and magnetic signals.
So far, the Navy’s most independent drones are its gliders. They’re autonomous systems that can travel for months using an ingenious “buoyancy engine” that taps the changes in ocean temperature and pressure to alter the robot’s buoyancy. Near the surface, the buoyancy decreases so the drone falls; in the depths, the buoyancy increases and the glider rises. As it falls and rises, the water pushing against its outstretched wings moves the glider forward. Their chief role so far is to collect and report oceanographic data.
But the Navy aims for robots that can do much more.
In the Pentagon’s 2011 Unmanned Systems Integrated Roadmap, the Navy unveiled its vision with a scenario set in the 2030s. The service described UUVs that will lurk near enemy submarine transit lanes and automatically attach themselves to passing subs. As they ride, they will transmit their location so that hostile subs can’t slip unnoticed through the sea.
Meanwhile, back in the real world, engineers at the Navy’s year-old Laboratory for Autonomous Systems Research are busy designing a new generation of spy drones. One drone employs four undulating fins copied from a reef-dwelling fish to swim in choppy near-shore waters while hunting for mines and gathering intelligence. Another, a winged drone, is designed to be dropped from a manned aircraft, fly to its operating area, then into the sea and fly beneath the surface gathering data.
But those, too, are years from being operational.
The Defense Advanced Research Projects Agency and defense contractor SAIC are developing a much more sophisticated surface drone to hunt for quiet enemy submarines. DARPA program director Scott Littlefield said the Anti-Submarine Warfare Continuous Trail Unmanned Vehicle — ACTUV — will be able to operate for months at a time and travel thousands of kilometers with little or no human intervention.
DARPA has released an artist’s rendition of a knife-nosed trimaran with a torpedo-shaped sensor pod protruding underneath. Last August, DARPA awarded SAIC a $58 million contract to build a prototype that’s ready for testing in 2015.
ACTUV is an ambitious effort, no doubt. Not only will the drone submarine hunter require advanced sensors to detect and track quiet diesel-electric submarines, it will need a propulsion system that can operate without human assistance for months, and an autonomous navigation system sophisticated enough to abide by maritime laws, Littlefield said.
Since it’s a surface vessel, it should be possible for human controllers to contact ACTUV from time to time, an arrangement the Navy calls “sparse supervisory control.” But the intent is for the sub hunter to operate autonomously most of the time.
If DARPA and SAIC can pull it off, the drone will be “an operational game-changer for the Navy,” Littlefield said. Again, it’s a matter of economics. The unmanned sub hunters are supposed to be cheap — about $20 million apiece. At that price, they could counter the threat of quiet submarines “at one-tenth the cost of building subs,” he said.
The Navy will need major breakthroughs in autonomy and propulsion for another ambitious drone — the Large Displacement Unmanned Underwater Vehicle, or LDUUV.
This unmanned mini-submarine is expected to be about 20 feet long, possibly weighing about 5 tons. The Navy plans to send it out for up to 70 days at a time to track enemy submarines, gather intelligence, find mines, drop off sensors and conduct “offensive operations,” which could include laying mines and launching torpedoes.
The LDUUV will need a propulsion system that’s able to run unattended and unrefueled for months at a time. Current plans say the drone must be able to deploy for 30 days at a time by 2014, and 70 days by 2017. The Navy is building a half-dozen prototypes, and Alan Schultz, director of the Navy robotics lab, said his team is working on a hydrogen fuel cell that he believes will meet the LDUUV’s power requirements.
But endurance is just one of the LDUUV’s challenges. To operate without human control, for more then two months at a time, the robot sub will have to be smarter than any drone that exists today.
It will have to be able to detect and avoid hazards in its path, from surface ships and other submarines to seamounts, sandbars, fishing nets and piers. Sonar and acoustic sensors can provide situational awareness, but the drone must also know what to do to avoid collisions and how to operate in compliance with international rules of the road.
That element of autonomy has Pentagon lawyers, university professors and other maritime law experts pondering how decades-old rules written for human mariners will apply to autonomous vehicles driven by autopilots and algorithms.
For example, rules spelled out in the International Regulations for Preventing Collisions — the “Colregs” — require that all vessels must “at all times maintain a proper lookout by sight and hearing” and by other means.
How does an unmanned vehicle comply with that?
“How many cameras constitute a lookout? Can the requirements be met with technology?” asked George Detweiler, a marine transportation expert with the Coast Guard.
The regulations also spell out how vessels must act when approaching, passing, overtaking or crossing the path of another vessel. And there are rules for what ships must do in the presence of vessels that have limited maneuverability, and vessels that are towing or fishing or under sail.
All of that and more will have to be programmed into the navigation systems and linked with the sensors of autonomous drones.
When it comes to Colregs, there is less uncertainty about remotely operated drones, Detweiler said. They’re considered to be manned and must comply with current regulations, even though an operator is not on board.
In addition to the Colregs, autonomous drones will have to be familiar with the United Nations Convention on the Law of the Sea, which spells out the rights and responsibilities of nations that use the oceans. The law, for example, establishes a zone extending 12 miles offshore as each nation’s territorial waters.
“Weapons practice and spying are banned in another country’s territorial waters, and underwater vehicles such as submarines are required to surface and show their flag when passing through,” said Stephanie Showalter, director of the National Sea Grant Law Center at the University of Mississippi.
Theoretically, drones could operate in a foreign nation’s territorial waters as long as they travel on the surface and do not threaten the nation’s peace, good order or security, Showalter said. But a drone lurking in territorial waters is automatically suspicious.
“It is likely that most drone operations would be considered prejudicial,” she said.
Drones, like manned vessels, will likely have more leeway to operate within a country’s 200-mile exclusive economic zone.
The Law of the Sea “preserves the rights of all states to navigate through it,” Showalter said.
But the law gives coastal nations jurisdiction over scientific research in the 200-mile zone. Would that preclude oceanographic data gathering by gliders?
“The Navy thinks it has right to collect hydrographic data no matter where it is. It’s a military function, but it’s essential to keeping maps up to date,” Showalter said. But the Navy’s opinion on that has been challenged, sometimes aggressively, in the past.
Sorting out how the Colregs will apply to drones is expected to take another 3½ years, Detweiler said. Proposed changes must be transmitted to the International Maritime Organizations maritime safety committee, then translated into multiple languages for the 170 member nations to study before they can be agreed to.
If that’s the case, in some ways, the technology will be ready far before the law catches up to it, said Martin, the drone consultant.
Still, what goes on underwater is so secret that “we don’t really know much about it,” he points out.