Underwater Drone Manufacturers Eye New Power Technologies
Experts agree that the future of unmanned underwater vehicles is bright, with more investment expected from both the government and commercial sector. However, power generation continues to be a conundrum for engineers.
UUVs need a tremendous amount of juice to complete the various missions for which they are deployed. Many stay under the waves for hours, days and even months at a time, all while carrying a variety of payloads.
Rear Adm. Mathias W. Winter, chief of the Office of Naval Research, noted that the Navy is investing science and technology dollars toward undersea platforms.
While UUVs and unmanned aerial vehicles are very different, the technology underlying both systems is similar, he said at Navy League’s Sea-Air-Space Conference in March. More testing is still needed in terms of power generation, sense-and-avoid, persistence and payload capability for both kinds of robots, he noted.
“All of that is underway,” he said.
ONR is currently working on developing the large-displacement unmanned undersea vehicle–innovative naval prototype, a device that will be able to prowl the littorals for months at a time. The system takes advantage of new energy technologies in order to power it for extended periods.
The program is “develop[ing] new air independent energy systems and core vehicle technologies to extend unmanned undersea vehicle endurance into months of operation time,” ONR materials said. “New energy sources for unmanned undersea vehicles will increase the current energy density significantly, allow for quick recharge or refueling, operate at an acceptable cost level and enable pier-to-pier operation with months of endurance.”
Air independent systems allow non-nuclear powered subs to stay submerged for long periods of time without having to surface for oxygen.
The vehicle has been in development since 2011. ONR recently announced that it would make a voyage from San Francisco to San Diego in 2016.
Officials hope the UUV will one day work alongside manned assets and unmanned aerial vehicles to give military leaders increased situational awareness, said Rear Adm. Mark W. Darrah, program executive officer for unmanned aviation and strike weapons.
In the future, “we’re going to have to operate large-displacement unmanned undersea vehicles simultaneously with an unmanned Fire Scout [helicopter] operating in a littoral area in concert … with a manned system,” he said. Using an MH-60 manned anti-submarine helicopter along with the underwater drone and the Fire Scout gives a “battle group commander a view that they’ve never had before.”
Industry is also focusing increasingly on unmanned underwater systems, and researching new ways to power them.
Battelle is currently developing a new technology called OceanHub that will allow for power and data transfer underwater, said Rich Granger, business development leader at Battelle Maritime Systems.
It is “almost like an underwater garage for a UUV,” Granger said. There is no physical contact and the power is transferred through a thin water gap.
Using honing technology, a UUV is guided into an underwater docking station. The vehicle drives through a cone and then is recharged using an inductive, non-contact power transfer system, he said.
The company demonstrated the product in Boston Harbor in 2011 where it was able to transfer power to a UUV with 74 percent efficiency. After improving the system and upgrading it, Battelle was recently able to increase the efficiency to 85 percent, Granger said. The company believes it can improve it to 90 percent with some component changes.
“We’ve been progressively improving the underwater efficiency for this power transfer technology to enable more rapid underwater recharging of UUVs so you don’t have to surface, maybe because you don’t have the time to do that, maybe because if it’s a defense operation, you don’t have the ability to surface,” he said.
The system could be integrated onto a variety of unmanned underwater vehicles, he noted.
At Huntington Ingalls Industries, one executive envisioned the day the company’s Proteus underwater vehicle could run on fuel cells.
The dual-mode underwater vehicle was created by The Columbia Group’s Engineering Solutions Division (ESD) and Battelle, and can be manned or unmanned. Earlier this year, Huntington Ingalls acquired ESD as a subsidiary and renamed it the Undersea Solutions Group.
Proteus can travel hundreds of miles and can hold various payloads. When in a manned mode, it can serve as an underwater delivery vehicle for special operators and carry six combat swimmers, said Ross Lindman, senior vice president of operations for the Undersea Solutions Group.
“It’s the only dual mode undersea vehicle that can operate either manned or unmanned,” he said.
It is currently powered through gigantic lithium polymer batteries — provided by Battelle and Bluefin Robotics — that lie on the bottom of the vehicle, Lindman said.
The battery can discharge 150 kilowatts of energy per hour, said Fred Byus, general manager of Battelle’s maritime systems division. “Most of the batteries in UUVs are … 15 to 20 kilowatt hours.”
In the future, the Navy will likely need UUVs to go on voyages that exceed 1,000 miles. Using fuel cell technology, Proteus could make that voyage, Lindman said. Fuel cells work by converting fuel into electricity through a chemical reaction.
“Going forward fuel cells are really [promising],” he said. “Proteus is readily adaptable to incorporate that technology.” There is a limit to what can be done with traditional batteries, he noted.
Fuel cells could potentially double or triple the vehicle’s endurance, Byus said.
With its current battery, it can operate for five days in unmanned mode and traverse hundreds of miles. There is an option to use single-use, primary cell batteries that would power the system for over 700 miles, Lindman said.
In manned mode, “the man becomes the limit, not the machine,” he said. Its endurance is based on how long operators can stay underwater, as the vehicle is flooded and anyone inside must wear full scuba gear.
The vehicle is currently being tested under an ONR program called advanced undersea weapons systems that seeks to arm Proteus, he said. It could one day be “the undersea equivalent of the Predator drone.”
It has previously been leased by the Navy as a testbed for undersea experiments. It currently has 400 hours of mission time and a little over 100 dives, Lindman noted. So far, it has only been used as a leased asset, though the company hopes a sale will be secured in the near future.
Industry is also working on unmanned technology that can be powered by the sea.
Liquid Robotics Inc.’s SHARC system consists of two parts, a surface vessel and a wing rack that remains about 20 feet below the surface of the ocean, said Gary Gysin, president and CEO of the company.
As the surface vehicle bobs up and down with the ocean’s waves, it pulls the wings of the rack up. When the vehicle hits the backside of a wave it pushes the wing down, creating propulsion, he noted.
“As soon as we deploy this in the water [and] we release the wing rack, it will start swimming,” he said. “It’s harnessing wave energy for all of its propulsion.”
There is an optional thruster that can be turned on for additional speed, he noted. It is powered by solar energy collected from the surface vessel. Solar energy also juices up the device’s computer, communication software and payloads.
The system can be used with a variety of payloads, including environmental assessment sensors that collect information on wave height, wind speed, barometric pressure and water current speed.
On the defense side, it can be used for intelligence, surveillance and reconnaissance as well as to detect submarines or other surface vessels, Gysin said.
SHARC has strong interest abroad, he noted.
“In Asia [interest is] quite strong. There is lots of water, there are lots of border disputes [and] there is lots of illegal fishing,” he said.
Using a ship or unmanned aerial vehicle to patrol these areas can be extremely expensive. SHARC offers an affordable alternative, he said. While prowling the sea, the systems can alert other more costly assets — such as an aerial drone or manned aircraft — to investigate suspicious areas through a real-time, secure data link, he said.
“We’re basically collecting data and then we’ll tip and queue somebody else to go interdict,” he said.
The Royal Australian navy and the Japanese coast guard have deployed the system, he noted.
SHARC can stay underwater for a year, and is only removed to make repairs and for cleaning, such as removing barnacles. The systems are also survivable and have weathered 16 hurricanes and typhoons, including a category 5 storm, all while continuing to transmit data, Gysin noted.
“We’ve never lost a vehicle in a hurricane or typhoon,” he said.
Liquid Robotics recently began a strategic relationship to integrate the system with Boeing’s large architecture, said Egan Greenstein, senior director of autonomous maritime sales at Boeing’s military aircraft division.
The companies want SHARC to work alongside the Boeing Insitu ScanEagle unmanned aerial vehicle, Greenstein said.
“SHARC can tell the operator, ‘Hey, there is a new unknown surface vessel coming up from the south,’ and that operator can immediately click on the target and send a ScanEagle to go look at it,” he said.
The system can also be used alongside unmanned underwater vehicles to improve communication capabilities, he noted.
Because SHARC lives at the surface of the ocean, it can communicate with underwater vehicles as well as air and space assets, Greenstein noted. For example, it can serve as a communication relay for Boeing’s Echo Ranger autonomous underwater vehicle while it is still below the sea.
“This is actually a solution where we can provide a real-time communication service to manned submarines, underwear vehicles, ROVs [remotely operated underwater vehicles], seafloor infrastructure like sensors … and connect those in real time up to shore via satellite communication or to an aircraft,” he said. “They can see in real time what is going on, and if they need to, command that underwater vehicle.”
Liquid Robotics and Boeing are currently working on ways to allow SHARC to autonomously tell a ScanEagle to investigate a suspicious area. “That part is really right around the corner,” Greenstein said.