Robots at sea: underwater UAVs making waves
Image credit: Marina Militare
Shoals of small cooperative robots that can gather vast amounts of data inexpensively, can communicate with each other, and are smart enough to alter their mission in response to a changing situation, are coming close to operational reality in navies around the world.
Military autonomous underwater vehicles or AUVs have, until now, come with hefty price tags. However, small innovative companies around the world are changing that. E&T visited the Marine Robotics Innovation Centre at the National Oceanographic Centre in Southampton, and the SeaFuture exhibition at the Italian Naval base in La Spezia, to find out more.
“We’ve learned that the Navy doesn’t want data, they want information, and machines simple enough that Jack Sailor can deploy in quantity without large, complex equipment,” says Terry Sloane, managing director of Planet Ocean Ltd. “It makes sense to load one or two sensors on many little robots instead of loading them all on to one single, very expensive AUV.”
A fleet of small robots or micro AUVs can cover a large area quickly, and with improvements in battery technology and power management systems Sloane expects the endurance of these machines to be as much as 48 hours or 200km by the end of 2018 or early 2019.
This longer range provides much greater mission capabilities. Ideal tasks could be covering a large search area for the swift detection of a downed aircraft’s black box before it stops transmitting, searching an area for mines, or in combat hydrography, surveying an area such as a proposed landing beach, or searching a harbour for mines, providing valuable pre-op feedback to combat divers ahead of a mission.
Each robot carries a small inertial navigation system (INS) like those found in mobile phones. Also, there is an acoustic or hybrid acoustic and optical modem for communications to talk to the other members of the shoal which sends data to the mothership and receives mission instructions. Additional sensors pertinent to the mission, such as cameras, side-scan or multi-beam sonar, can be easily added to equip the robots for the job.
Customisable and versatile, these hardware solutions are becoming almost mundane. Large AUVs have the luxury of expensive high-accuracy INS and bottom-tracking Doppler velocity logs to accurately determine their position in the GPS-denied environment under the waves. However, such equipment would be too large, too expensive and use too much power to be practical for micro AUVs.
Algorithms that interpret the low-accuracy INS data, combined with the acoustic data from swarm members to determine the relative position of each device, alters the job of navigation in these small robots. By sharing information on how they are being influenced by the currents, the shoal can use AI to make real-time adjustments and improve their navigation without expensive hardware.
Dr Michele Cocco, managing director of Italy’s Edgelab and developer of the U-tracker AUV, says unit costs are tumbling, following the trajectory of their aerial drone counterparts. “Small, expendable, low-cost AUVs are now possible because of a convergence and timely maturation of a number of technologies: 3D printing for parts, high-density lithium polymer batteries, and low-cost sonar, combined with algorithm developers in navigation and control making their coding open-source.
“Our next challenges are the inexpensive launch and recovery from zodiacs or similar craft such as USVs [unmanned surface vehicles], perfecting inter-vehicle communications and ultimately the introduction of independent intelligent action – no small ask,” he adds.
Like the difficulties faced by first-generation ‘Dr Who’ daleks and stairs, or Boston Dynamics robots and door knobs, the simple task of charging underwater bots remains a challenge. Many still depend on human intervention to plug them into a recharging station on board their mothership. The likely solution will lie in wireless inductive charging, where the robots simply park on a plate to recharge at stations deployed in areas where AUVs operate. Several navies are already testing these systems.
Subsea robots that support human divers
The role of the combat diver is far from obsolete, and the future will combine the human element with robotics; each will have their place. Giovanni Modugno sees robots as a useful adjunct to his men’s skillsets.
Modugno, the commander of the Italian Navy Explosive Ordinance Disposal (EOD) and Deep Diving Unit, explains: “We constantly use robots in our work in bomb disposal and salvage. Micro ROVS were very useful during our work on the Costa Concordia,” referring to the cruise ship that ran aground in 2012, resulting in 33 deaths. The complex raising and salvage operation was finally completed in 2017.
“Our job was to make a forensic examination of the wreck to determine exactly what happened, and to retrieve the bodies. We used a mini-ROV from GNOM; our divers would take the ROV to a squeeze point where they could not enter and send in the robot to safely film and map the area.”
Modugno’s team is already using autonomous Zodiac inflatable boats, sending them ahead of human divers to map an area with sonar. “The advantage is that we tactically don’t risk the diver until we need to, and it is very time-efficient, with these USVs searching an area far faster than a diver can.”
As on land, robots can also be used to relocate dangerous ordnance away from populated areas or harbours. In 2017, the Italian Navy neutralised 22,000 explosives from rivers, lakes and the sea, most dating from the Second World War.
Another area where further development is needed is inter-vehicle communications, as Wi-Fi transmission is still difficult to do successfully underwater. Acoustic transmissions have low bandwidth (as little as 250-byte packets per minute), dissipate quickly and are not exactly covert, meaning an enemy can listen for them.
In the future, these cooperative micro-subs could be delivered to the operations site by a USV, or at a greater distance from the mothership, by unmanned aerial drones. Aerial delivery is far from being science-fiction, as it is already being tested.
Calzoni, a subsidiary of L3 Technologies – which supplies command and control, communications, intelligence, surveillance and reconnaissance systems – has developed several USVs that can be customised for different tasks, including search and rescue, harbour protection, mine-hunting or anti-submarine warfare. “Vehicles like this will eventually operate autonomously ‘over the horizon’ well away from their launch vessels, but for now the battery-operated MiniRanger can operate for up to eight hours on a pre-programmed course scanning for mines, automatically towing two sonars behind it at a preselected depth down to 100m,” says business development director Gabri Pasini.
The MiniRanger is currently undergoing tests with the Italian Navy for mine-hunting operations. Ultimately, the goal is higher-level autonomy with enhanced environmental awareness and, critically, obstacle avoidance. All autonomous marine vehicles must conform to COLREGS, the navigational rules published by the International Maritime Organization (IMO) to be followed by all vessels to prevent collisions at sea. The integrated use of USVs with remotely operated vehicles (ROVs) or AUVs in future missions will permit more complicated mine countermeasure tasks. These USVs could also be used to launch and recover swarm AUVs – delivering them covertly into a deployment zone and returning to retrieve them after their mission has ended.
Not all the newest developments in naval robotics are small in scale. Italian ROV developer idRobotica has been developing battery-powered robots for over 40 years for the military and oil and gas sectors. Its Pluto Plus is already deployed with some navies around the world. Like most companies at SeaFuture, idRobotica is unwilling to discuss specific clients.
The 320kg mine-identification and disposal robot is capable of operating in a 3-knot current in zero-visibility conditions up to 600m deep: a situation that would be impossible for a human diver. The Pluto can operate autonomously in a pre-programmed mode, or a pilot can take over manual control via a 2,000m optical cable attached to an AUV or radio buoy at the surface.
“When Pluto Plus is used with a tethered buoy, the pilot can take command using Wi-Fi from his position on the mothership. He can also have a real-time video link to the vessel’s cameras,” says Federico Orlando, contract manager for the company. “Uniquely the ROV has all its sensors in a rotating head that can pan and tilt 180 degrees, allowing it to hover over a mine while the operator drops a destructive charge with a time-delay mechanism. If the Pluto has been deployed by an AUV it can quickly return to the safety of the vessel via a moon pool [an open well in the base of the hull of a ship that allows direct access to the water].”
An experienced anti-submarine warfare officer searching for enemy submarines might order a shoal of small robots to be sent out by an ASV or launched from an unmanned aerial vehicle to map the ocean thermoclines well ahead of the fleet. These zones of abrupt temperature change are important in submarine operations because sonar is used to locate enemy submarine vessels, but the active acoustic signal will bounce off the thermocline due to the differential in water density.
With their fast mapping capability over a wide area, a shoal of robots could report the exact location of the thermoclines to the anti-submarine vessel, pinpointing areas that submarines are likely to choose for hiding. Once detected, a submarine can then be tracked by follower robots. Conversely, a submarine commander could launch a shoal of micro-AUVs from their torpedo tube to locate an effective hiding place.
Darpa is planning sea-floor pods housing drones that can be released when a signal is received, perhaps to track a submarine or to rise to the surface for aerial operation.
Earlier this year, the US Navy incorporated an autonomous vessel into its fleet. The Sea Hunter is the world’s largest unmanned drone warship, designed by the Defense Advanced Research Projects Agency, better known as Darpa. The 40-metre single-hulled ship has two outriggers for additional stability in high seas, has the capacity to be armed, and operates at a fraction of the daily cost of a similar manned vessel. Initially conceived as an anti-submarine platform, it clearly has many potential uses: resupply runs into war zones, ferrying injured sailors back to safety, or any high-risk activity where the loss of human lives would be unacceptable.
The Chinese also have huge ambitions in underwater military robotics and seem determined to challenge the US in this area. Lin Yang, the lead scientist on a classified programme developing next-generation military underwater robots, spoke recently to the English-language South China Morning Post, stating that “robot boats are intended to supplement the Chinese Navy’s manned subs by handling such tasks as surveillance, mine-laying, and even attacks on enemy vessels, relying on AI to adjust to changing conditions.”
The speed of innovation in the marine robotics sector means that many navies are having to change often lengthy and cumbersome procurement processes to respond quickly to technological change. Traditional relationships with the big defence behemoths like Lockheed Martin or Boeing are being supplemented by multiple cooperative working arrangements with nimbler, smaller companies and university researchers at the leading edge of robotic research.
Of course, any robot that has been originally developed for ocean environmental mapping, or for mapping harbour security or mine-hunting, can, with a few tweaks and a different payload, be deployed in an offensive situation, sent out to encounter and destroy enemy ships, submarines, divers or to disable harbour defences.
At this current stage of development, the embedded AI in any robot can certainly not be trusted to differentiate friend from foe, but it is now that we humans should be having a global conversation about the ethics of military war machines. Are we ready for autonomous self-determined robots roaming the seas?
Singapore is currently testing an array of acoustic nodes that are anchored to the seabed around the island nation and will serve as a subsurface listening net for drones and submarines.
Meanwhile, the Norwegian Defence Research Establishment (FFI) has said that it has developed an acoustic array that can be towed behind a drone. This could be programmed to mimic a submarine and fool enemy submarine-detecting drones, luring them away.
Hard facts about the capability or current extent of the underwater Great Wall of China are hard to come by, but the Chinese government certainly has plans to complete a sensor array that would monitor shipping, submarine, and drone movement in the South China Sea. The plan for a network of floating and submerged sensors complete with a fleet of underwater drones has military strategists around the world concerned.
Chinese military sources suggest that the array may in the future link up with a proposed 3000-metre-deep manned underwater ‘space station’ that would primarily be used for deep sea mining and other resource development in these highly disputed waters. However, this deep station is at least a decade away.