Unmanned underwater vehicles (UUV), sometimes known as underwater drones, are any vehicles that are able to operate underwater without a human occupant. These vehicles may be divided into two categories, remotely operated underwater vehicles (ROVs), which are controlled by a remote human operator, and autonomous underwater vehicles (AUVs), which operate independently of direct human input. The latter category would constitute a kind of robot.
The navies of multiple countries, including the US, UK, France and Russia, are currently creating unmanned vehicles to be used in oceanic warfare to discover and terminate underwater mines. For instance, the REMUS is a three-foot long robot used to clear mines in one square mile within 16 hours. This is much more efficient, as a team of human divers would need upwards of 21 days to perform the same task. In addition to UUVs with the purpose of clearing out mines, autonomous submarines began to be prototyped as of 2008. Especially autonomous submarines face much of the same ethical issues as other unmanned weapons. Other applications include ship hull inspection (Bluefin), wreck inspection (Blueye Pioneer), nuclear reactor decontamination, exploration, and mining/drilling.
Due to the advancement of technology weapon systems have become more sophisticated and capable for multi role missions, which allows the unmanned underwater vehicles to play a crucial role within military communities. Having these unmanned underwater vehicles allows military personnel to control the vehicle without actually being inside it, cutting casualty numbers significantly. Another benefit of moving to an unmanned vessel allows the vehicle to be submerged for longer periods of time because of the lack for resupply (food, water etc..) and oxygen. An additional major application unmanned underwater vehicles have is serving the naval warfare community. Most naval forces have difficulty with coastal combat, as large ships venture near shore they will become grounded. This dilemma allows unmanned underwater vehicles to fulfill a unique role within the military community as these vehicles can access these coastal shallow areas unlike their manned counterparts. The versatility of these vehicles allows them to perform many missions, while also being more cost effective and preserving military personnel.
A survey conducted by the United States military analyzed the top missions in which the unmanned underwater vehicles could fulfill. The most beneficial missions unmanned underwater vehicles provide include; intelligence, reconnaissance, mine countermeasures (mine sweeping etc.), and submarine warfare. These are listed from most important to least, knowing this unmanned underwater vehicles will most likely be used for reconnaissance missions to gather intelligence on other forces, etc. However these unmanned underwater vehicles are very versatile and can be utilized for many different roles within the United States military (United States Navy).
UUVs are commonly used in oceanic research, for purposes such as current and temperature measurement, ocean floor mapping, and Hydrothermal vent detection. Unmanned underwater vehicles utilize seafloor mapping, bathymetry, digital cameras, magnetic sensors, and ultrasonic imaging. The Woods Hole Oceanographic Institution employs a vehicle called the Sentry, which is designed to map the ocean floor at depths of six thousand meters. The vehicle is shaped to minimize water resistance during dives, and utilized acoustic communications systems to report the vehicles status while operating. Unmanned underwater vehicles are capable of recording conditions and terrain below sea ice, as the risk of sending an unmanned vehicle into unstable ice formations is much lower than that of a manned vessel. Glider type unmanned vehicles are often used to measure ocean temperatures and current strengths at various depths. Their simplicity and reduced operating costs allow more UUVs to be deployed with greater frequency, increasing the accuracy and detail of ocean weather reporting. Many UUVs designed with the purpose of collecting seafloor samples or images are of the towed type, being pulled by a ship's cable along either the seafloor or above. Towed vehicles may be selected for tasks which require large amounts of power and data transmission, such as sample testing and high definition imaging, as their tow cable serve as the method of communication between controller and craft. Science Direct claims the use of Unmanned Underwater Vehicles has risen consistently since they were introduced in the 1960's, and find their most frequent use in scientific research and data collection. Oceanservice describes Remote Operated Vehicles (ROVs) and Autonomous underwater vehicle (AUVs) as two variations of UUVs, each able to accomplish the same tasks, provided the craft is properly designed.
OODA Technologies, a data collection and analysis company, is highly interested in utilizing UUVs along the coasts of Canada. According to OODA, these unmanned craft provide much greater coverage of an area at a much lower cost. The quality of the data returned by unmanned marine vehicles is also stated to be much higher than that of traditional manned craft.
These examples of applications took place during the fourth iteration of the Advanced Naval Technology exercises, in August at the Naval Undersea Warfare Center Division Newport. The first example of unmanned underwater vehicles was displayed by Northrop Grumman with their air drop sonobuoy's from a fire scout aircraft. Throughout the demonstration the company used the: e Iver3-580 (Northrop Grumman AUV) to display their vehicles ability to sweep for mines, while also displaying their real-time target automated recognition system. Another company by the name of Huntington Ingalls Industriespresented their version of a unmanned underwater vehicle by the name of Proteus. The Proteus is a dual-mode undersea vehicle developed by Huntington and Battelle, the company during the presentation displayed their unmanned underwater vehicle capabilities by conducting a full-kill demonstration on sea bed warfare. Throughout the demonstration the vehicle utilized a Synthetic aperture sonar which was attached to both the port and starboard of the craft, this allowed the unmanned underwater vehicle to identify the targets placed underwater and to ultimately eliminate them. A quote from Ross Lindman (director of operations at the company's technical solution's fleet support group) stated that "The big significance of this is that we ran the full kill chain," he said. "We ran a shortened version of an actual mission. We didn't say, 'Well we're doing this part and you have to imagine this or that.' We ran the whole thing to illustrate a capability that can be used in the near term." The final demonstration for unmanned underwater vehicles was displayed by General Dynamics, the company show cased their cross-domain multi-platform UUV through a theater simulating warfare planning tool. Through the utilization of this simulation, they showed a Littoral combat ship along with two unmanned underwater vehicles. The goal of this exercise was to demonstrate the communication speed between the operator and the UUV. James Langevin, D-R.I., ranking member on the House Armed Services Committee's subcommittee on emerging threats made a statement in regard to this exercise "What this is all driving to is for the warfare commander to be able to make the decisions that are based on what he thinks is high-confidence input quicker than his adversary can," he said. "That's the goal -- we want to be able to ... let them make warfare-related decisions quicker than anybody else out there." These exercises were conducted to showcase the applications of unmanned underwater vehicles within the military community, along with the innovations each company created to better suite these specific mission types.
A major concern with unmanned underwater vehicles is communication. Communication between the pilot and unmanned vehicle is crucial, however there are multiple factors that might hinder the connection between the two. One of the major problems involves the distortion of transmissions underwater, because water can distort underwater transmissions and delay them which can be a very major problem in a time sensitive mission. Communications are usually disturbed due to the fact that unmanned underwater vehicles utilize acoustic waves rather than the more conventional electromagnetic waves. Acoustic wave transmissions are often delayed anywhere from 1-2 seconds because they move more slowly than other types of waves. This is not including environmental conditions that can also hinder communications such as reflection, refraction, and the absorbing of signal. These effect within the water overall scatter and degrade the signal, making this communication system fairly delayed when compared to other communication sources. Another system that utilizes the acoustic waves is within the navigation of these unmanned vehicles, precise navigation is a must for these unmanned vehicles to complete their missions. A popular navigation system aboard these unmanned underwater vehicles is acoustic positioning, which is also faces with the same problems as acoustic communication because they use the same system. The Royal Netherlands Navy has published an article detailing their concerns surrounding unmanned marine vehicles. The Royal Netherlands Navy is strongly concerned with the ability of UUV's to evade detection and complete tasks not possible in manned vessels. The adaptability and utility of Unmanned Underwater vehicles means it will be difficult to predict and counter their future actions.
On December 16, 2016, a Chinese warship seized an underwater drone that was in the process of being retrieved by the U.S. Navy ship USNS Bowditch. A day later, the Chinese Defense Ministry said it will return the drone to the United States. The Pentagon confirmed that and says the drone, used for gathering weather and temperature data, is not armed. The drone was returned several days later.