Navigation for Unmanned Underwater Vehicles (UUVs)

Navigation for Unmanned Underwater Vehicles (UUVs)

The operators of Unmanned Underwater Vehicles (UUVs) need to know where their vehicles are at all times. The greater the locational accuracy, the more extensive the scope of their missions can become. Doppler Velocity Log (DVL) solutions are well suited to meet the highest navigation requirements.

DVLs provide an effective navigational solution for Unmanned Underwater Vehicles (such as the AUV shown here), allowing them to complete long-duration missions safely.

Highlights

  • Highly accurate velocity data for location estimates
  • Ultra-small size and weight
  • Easy to integrate into complete navigation aids
  • Exceptional range

What and why

What is DVL for UUV navigation and why is it useful?

Underwater, the luxury of GPS to provide speed and location data is not available. DVL technology, paired with a high-quality compass, provides a valuable alternative, offering high-accuracy location and speed data for UUVs.

DVLs are a key component in the default solution for those seeking continuous navigation data for their UUVs, whether ROVs or AUVs. Alternative options only provide intermittent data. 

A DVL is a proven navigation system used by leading navigation experts, providing precise positioning data, while being simple to use.

Instruksjoner
Operators of ROVs can use DVL navigation to accurately control the behavior of the ROV. This image shows an ROV used by the Norwegian University of Science and Technology (NTNU), with a Nortek DVL installed.

Who it's for

Anyone developing and integrating UUV systems who requires continuous and accurate navigation should consider a DVL.

Operators of ROVs doing precision work – for example, in the oil and gas industry – can use DVL navigation to accurately control the behavior of the ROV in order to maintain that precision. DVLs are suitable for vehicles ranging from rugged remotely operated vehicles (ROVs) to the smallest craft operating in our oceans. 

Autonomous underwater vehicles (AUVs), which have no direct communication with their operators, require DVL navigation. DVLs provide an effective navigational solution for AUVs, allowing them to complete long-duration missions safely.

DVL tracking helps ensure that their planned mission – perhaps for a survey or for military purposes – is carried out effectively. The longer an AUV’s mission, the greater the need for the accuracy a DVL offers.

Technical considerations 

There are three basic considerations when selecting the correct DVL: depth rating, the desired range over the sea floor, and size and weight. The depth rating determines whether the DVL is assembled with a lightweight, plastic Delrin housing or a deepwater titanium housing. The maximum range for which a DVL can track the bottom is determined by the transmit frequency; this may either be 1000 or 500 kHz. The size and weight are determined by these first two choices (depth rating and transmit frequency). The weight is determined by the material, and the size by the frequency (higher-frequency DVLs are smaller in size).

The DVL may be used in a configuration by an Original Equipment Manufacturer (OEM), where the DVL is integrated into the manufacturer’s product without its external body, or pressure housing. This provides a tighter mechanical integration into the manufacturer’s vehicle.

Those new to the technical considerations involved would also benefit from reading New to subsea navigation.

Data presentation

A DVL is commonly paired with an inertial navigation system (INS), whose providers typically provide their own presentation of position or tracks. Alternatively, the system integrator may create their own.

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Nortek’s DVL instrument plays a central role in Fusion, a unique new approach to hybrid underwater vehicles that combines AUV and ROV capabilities with diver navigation and propulsion in one system.

Choice of instrument

The compact size of systems incorporating Nortek DVLs makes the equipment easier to integrate with UUVs.

The DVL1000 is the industry’s smallest DVL. The DVL1000 – 300 m is the shallow-water version and has a maximum operational depth of 300 m. It is ideally suited for subsea navigation where size and weight are a concern. The DVL1000 can bottom-track in a 0.2–75 m range.

The slightly larger DVL500 has a greater range than the DVL1000. It can bottom-track in the 0.3–200 m range.

Nortek also provides versions of these models capable of being fitted to UUVs carrying out industry applications at greater depths. These instruments have titanium housings, allowing them to work further below sea level. The deepwater version of the DVL500 can operate down to 6000 m, while the DVL1000 can operate down to 4000 m.

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