AUV's, or Autonomous Underwater Vehicles, have been used by scientific laboratories, government agencies, militaries, and private companies for over 40 years. The first AUVs were highly specialized, and were limited in scope to the specific task that they were designed to complete. Since then, technology has progressed allowing AUVs to become dynamic platforms for a variety of imaging, chemical, biological, acoustic, and oceanic sensors that can be changed with ease based on the needs of the mission.
Watch this Introduction to AUVs from Black Laser Learning:
AUVs differ from other underwater vehicles in that they are unmanned, completely untethered from surface ships (or other vehicles), highly maneuverable, and either follow a preprogrammed navigational path or use their sensors to find and survey objects of interest. AUVs are often used in the oil industry to survey underwater pipelines where they can automatically find a pipeline and follow it, and even reacquire pipelines if they become buried under the seafloor. AUVs often have front-facing collision avoidance sonar in their nose to detect unexpected obstacles in their path.
Within the past decade AUVs have been used in many habitat mapping studies, from aiding in fishery stock assessments to monitoring invasive species. They've been very useful to scientists due to their ability to continually image the seafloor from predetermined, fixed heights above the ocean's bottom while compensating automatically to match the seafloor's changing topography. In addition to recording photos and video, AUVs can also collect information about water temperature and salinity, and can use different types of sonars (bathymetric and side-scan sonars) to gain detailed information about the bathymetry and morphology of the seafloor.
The images that you're exploring in SubseaObservers were recorded by the AUV "DORA" (Delaware Oceanographic Research Autonomous underwater vehicle) from the University of Delaware's Coastal Sediments, Hydrodynamics, and Engineering Laboratory (CSHEL). DORA is a Gavia class AUV and can operate at depths of up to 500m.
Explore the green dots in the image below to learn more about about DORA's systems.
Obstacle Avoidance Sonar
Geoswath Bathymetric Sonar
Doppler Velocity Log (DLV)
Inertial Navigation System (INS)
Water Quality Sensor
For the scallop image survey, DORA took continuous images at an altitude of approximately 2 meters (6.5 feet) off the seafloor, at depths of up to approximately 30 meters (98.4 feet). Gavia AUVs are built using plug-and-play modules, allowing them to be configured in the field by inserting the required modules for the task at hand. DORA was configured to record photos in addition to water depth, temperature, salinity, oxygen concentration, and information about the seafloor via bathymetric and side-scan sonar.
For the sea scallop survey, each of DORA's missions would begin by programming the survey path into DORA's navigation computer and lowering it over the side of the scallop fishing vessel 'Christian and Alexa'. Once in the water, a wireless signal would be sent to DORA to begin the mission, instructing it to follow the preplanned survey path.
DORA would begin taking photographs and other readings with its sensors once it reached the programmed depth, and information about the AUV's location would be maintained by an acoustic towfish that is towed below the water's surface by the fishing vessel. If for some reason DORA had to abort its mission, it would return to the surface and send information about its location to the fishing vessel via satellite phone.
After completing a mission, DORA would return to the surface at a predetermined location for pickup. Once onboard, the data stored in DORA's hard drives would be transferred to a computer to make room for the next mission's data. Between missions, DORA's battery module would be swapped out with a freshly charged battery, and systems checks would be made, inside and out, to make sure it's in good working order for the next mission. After a mission, DORA can be back in the water in less than an hour.
Check out this video to see what a dive looks like from DORA's point of view as it flies over the Aquarius Reef Base near Key Largo, Florida:
- University of Delaware's Coastal Sediments, Hydrodynamics, and Engineering Laboratory
- Teledyne Gavia (the makers of AUVs like DORA)
- Black Laser Learning's DVD series on AUVs
- Aquarius Reef Base
- NASA Extreme Environment Mission Operations
- NASA Pavilion Lake Research Project
- DeepWorker Submersibles, Nuytco Research
What's an AUV?
How are AUVs controlled?
AUVs in Science
AUV Mission Breakdown
Learn more about AUVs