SeaBED-class AUVs – The Deepwater Imager

The SeaBED AUV, developed by WHOI scientist Hanumant Singh and colleagues, is an AUV that can fly slowly or hover over the seafloor to depths of 6,000 feet (2,000 meters), making it particularly suited to collect highly detailed sonar and optical images of the seafloor. SeaBED flies about 8 feet (2.5 meters) above the seafloor, flashing its strobe light and snapping a photo every three seconds. It maintains a constant altitude and speed of a ½ knot.

Over the last seven years SeaBED-class AUVs have shown their versatility on missions ranging from shallow coral reef surveys to searches for deep-sea hydrothermal vents, in environments ranging from the open ocean to the dense ice cover of the Arctic. Besides the original SeaBED vehicle, WHOI operates two other sister vehicles, the Puma and the Jaguar, both rated to 5000m and have built or are in the process of building five vehicles for other groups to operate. A variety of marine biological, geological and archaeological applications share the need for high-resolution optical and acoustic imaging of the seafloor.

There is a growing demand for AUVs capable of conducting imaging in deep waters and the seabed AUV is particularly suited to undertake these studies. Each AUV consists of two hulls connected by aluminum spars. Most of the negative buoyancy is in the lower hull, while most of the positive buoyancy is in the upper hull, making the vehicles naturally stable in pitch and roll. The vehicles are designed for low-speed photographic and acoustic bathymetric mapping, and are designed to fly and hover within a few meters of a rugged undulating sea floor. SeaBED-class vehicles are capable of working off of small coastal vessels or fishing boats of opportunity, and can easily be broken into components, simplifying air transport logistics.

These capabilities enable inexpensive deployments at remote sites. The complete source-code to all vehicles is provided to all users of SeaBED-class AUVs, making sensor additions or vehicle maintenance very simple. SeaBED-class vehicles are also much lower-cost than other AUVs on the market, according to WHOI. SeaBED is approximately two meters long and weighs nearly two-hundred kilograms. The vehicle has two main pressure housings, containing the electronics and the batteries. The electronics are located in the top hull, and connected to the batteries and sensors in the bottom hull, by wet cabling routed through the vertical struts. SeaBED is equipped with an RDI Workhorse Navigator ADCP for bottom-locked navigation, an Imagenex Delta-T imaging sonar for bathymetry capture and a custom camera system based on high dynamic range Prosilica cameras. It also has a WHOI MicroModem for acoustic communication and navigation, and a SeaBird CTD sensor for measuring salinity and water temperature. The main computer is a 1.2GHz Pentium processor, running Ubuntu Linux 8.04. The custom vehicle software is primarily written in the C programming language.

Source: Woods Hole Oceanographic Institution

Below: WHOI scientist Hanumant Singh preparing seaBED AUV for depoyment