Underwater robots have become essential tools in non-military missions such as the exploration of the oceans and offshore oil drilling. The U.S. Navy wants to capitalize on the available technology and deploy robotic vehicles — not just teleoperated ones but also more advanced systems that can execute missions autonomously.
The goal is to deploy unmanned vehicles that can find buried mines, pinpoint enemy submarines and help to protect coastal areas from terrorist attacks.
The Navy has designed and tested a number of underwater unmanned vehicles, or UUVs, but it has yet to begin producing them in large quantities. Officials in charge of UUV development programs say the service wants to continue to evaluate technologies and test prototypes until they can determine what systems best meet the needs of the fleet.
For the Navy, these vehicles represent a chance to free up sailors from “dull, dirty and dangerous” tasks that could be performed by UUVs, said Capt. Paul Siegrist, program manager for unmanned maritime vehicle systems at Naval Sea Systems Command.
Siegrist has asked experts from the National Defense Industrial Association’s undersea warfare vehicles group to assess technologies for future UUVs. They will identify advances in autonomy, materials, control, sensors, communications, launch and recovery and payloads, he said.
Until these studies are completed and the Navy has an opportunity to test systems at sea, it remains unclear how large a role the vehicles will play, Siegrist said.
UUVs’ shapes resemble small torpedoes and come in various sizes. The smallest weigh 25 to 100 pounds. Others range from 500 to 3,000 pounds. The largest can reach 20,000 pounds.
The Navy has begun employing UUVs in applications for shallow water mine warfare, oceanography and special warfare support. Vehicles are being tested aboard minehunting ships through a process known as “user operational evaluation system,” said Siegrist. A team of mine warfare specialists was equipped with two 7.5-inch diameter vehicles and a single 12.75-inch diameter vehicle, each outfitted with side scan sonars. These systems are man-portable or deployed from piers and small craft.
A future evaluation will include several UUVs that will carry more advanced sensors, such as synthetic aperture sonars. One of the goals is to develop a “surface mine countermeasure” UUV that would be operated from the Littoral Combat Ship or from piers.
The Navy also has been working on submarine-based UUVs, Siegrist noted. The focus has been on 21-inch diameter vehicles to take advantage of compatibility with existing torpedo tubes for launch and recovery. Larger UUVs had been under consideration too, but the Navy shelved that project because only four boats, the SSGNs, would be able to handle the large UUVs.
Among the 21-inch vehicles that the Navy tested are the near-term mine reconnaissance system, or NMRS, and the long-term mine reconnaissance system, or LMRS. But both showed only “limited success” in demonstrating the capability to operate UUVs from submerged submarines, said Siegrist.
A key shortfall in these vehicles was their outdated information-processing technology and lack of an “open architecture” that would have allowed sensor upgrades, he explained. That became a problem when the Navy decided to expand UUV missions into areas such as intelligence, surveillance and reconnaissance (ISR).
“This led to a desire for a mission reconfigurable UUV,” said Siegrist. At the same time, the decision was made to incorporate large bow tubes in the Virginia-class attack submarines. This provided an expanded “customer base” for large diameter UUVs, of up to 36 inches. “The result was that the Navy decided to reexamine the potential for using large diameter UUVs from submarines to determine the way ahead,” he said.
Rear Adm. Mark Kenny, director of the Navy irregular warfare office, said that larger UUVs are more useful for ISR missions, particularly in non-traditional operations such as counterterrorism.
“We’ve shifted to large-diameter rather than 21-inch UUVs because we need endurance, we need payload, and we couldn’t get it with 21-inch vehicles,” Kenny said at a Washington, DC, conference hosted by the Association for Unmanned Vehicle Systems International.
Siegrist predicts that the role of unmanned systems in naval forces will expand, but UUVs are not likely to become substitutes for manned vessels. “No matter how far we advance in propulsion, energy sources, payload and autonomous capability, I do not see a near-term future in which the UUV gains the multi-mission flexibility and reasoning to replace our manned systems,” he said.
“It is not a technology issue; it is a cultural issue and the sooner we get UUVs to sea in operational situations the sooner we will gain acceptance that these systems are valuable assets to the war fighter.”
So far, the Navy has no UUV procurement programs under way. “We have a set of capabilities that may be nearing that phase, but as of now, we have no acquisition programs of record,” Siegrist said.
One of the most challenging technologies that the Navy is trying to advance is autonomy, so UUVs can operate independently.
Robert Manning, program officer with the Office of Naval Research, said the Navy is testing new software with algorithms that allow vehicles to make their own “decisions.” They would potentially be able to locate underwater mines, he said. Tests are planned for 2011.
The algorithms are based on a number of criteria, such as whether the water is clear or murky. If the system finds no mines in clear water, chances are there is nothing there, Manning said. But if it locates nothing in muddied water, the vehicle might continue the search or call for additional units.
The combination of these new algorithms and advanced sensors has translated into improved obstacle avoidance in harbors, where UUVs would have to dodge rocks, ships, small boats and shorelines, Manning said. This technology could prove useful for homeland security missions such as port protection.
Another promising UUV project is the “Bluefin 12” — a 5-foot craft whose primary mission is to locate buried or partially buried mines on the ocean floor. It will be ready for demonstrations in 2011.
The vehicle uses the Global Positioning System to find mines up to 100 yards away, Manning said. Once the vehicle comes close to a mine-like object, it swims over it in a star pattern — allowing cameras to view it from multiple directions — and reads its magnetic signature.
Bluefin has electro-optical cameras that are necessary to see in murky waters. It also has an “underwater electro-optic imager” laser that can project enough light to see through heavy sediment.
Suspected mines can be viewed from various angles, which helps reduce false alarms, Manning said.
“Overall, the military has really only just begun to scratch the surface of the utility of unmanned systems, especially at sea,” said Nathan Hughes, an analyst at Stratfor. “But there also seems to be an increasingly clear recognition of their promise.”
Unlike unmanned aircraft, UUVs have not yet become essential war tools, he said. “There has not been the same sort of rich operational experience [with sea systems] that really drives experimentation and doctrinal integration.”