An autonomous underwater vehicle (AUV) is a self-propelled robotic device controlled and piloted by an on-board computer that is programmed prior to the vehicle's submersion. AUVs are part of a larger group of underwater vessels termed unmanned underwater vehicles, which also includes remotely operated underwater vehicles (ROVs) controlled by a pilot on the surface by way of a tether or umbilical. The AUV is not only unmanned and untethered, it also controls its own movements in the water based on its programming and any of a number of various measurements that it constantly reads.
The first known autonomous underwater vehicle was developed at the University of Washington in 1957. In the 1970s other institutions, such as the Massachusetts Institute of Technology, began developing the technology. The growth of AUVs was initially limited because of the lack of other technology available, weak power supplies and stunted processor capabilities.
There are many types and designs of AUVs. Sizes range from smaller, portable, lightweight models to larger ones that can be 32 feet (10 m) long. The larger AUVs tend to be much more popular in the commercial sector because of their substantial increase in range and endurance over the smaller ones. A smaller autonomous underwater vehicle is significantly cheaper, however, and it often is the choice of the more budget-minded universities and research institutions.
Most AUVs follow the traditional torpedo design. There are other designs that allow operators to more easily change out components and equipment. The torpedo form, however, seems to allow for the greatest balance between all desirable traits.
Underwater gliders, a type of autonomous underwater vehicle, have been developed and see frequent use. The underwater glider is an ultra-low-power, long-distance AUV that is capable of remaining at sea in open ocean for months before returning. It will periodically relay data to its programmer via satellite. The underwater glider converts vertical motion to horizontal motion by slightly adjusting its buoyancy and wings. This allows the glider to remain at sea significantly longer than most AUVs — perhaps even months longer.
Overall, there tend to be three markets that regularly employ AUVs. The military uses them for battle space preparation and mine countermeasures. In the commercial sector, gas and oil companies invest in AUVs for offshore scanning. In the scientific sector, universities and research institutes utilize the AUVs for field tests and research.