In pursuing advances in cooperative robotic control and communication, Daniel Stilwell is developing a platoon of autonomous underwater vehicles (AUVs) that will both study the ecological effects of man-made nutrients on Virginias coastal waters and help develop search, survey, and tracking methods for the U.S. Navy.
|The Virginia Tech Miniature Autonomous Underwater Vehicle (AUV) is the smallest known deployable underwater vehicle developed. At 70 cm long and 8.9 cm wide, it has an expected cruising speed of 2-3 knots and range of 30 km. Payload capability includes a hard drive for high-density mission data storage. A fleet of Virginia Tech AUVs will be used to help the Navy develop underwater search and tracking capabilities and will help marine scientists determine the impact on coastal water of runoff from agricultural and urban land uses.
2 Prestigious Awards from NSF and ONR
He has recently won two prestigious young faculty awards to support these efforts: a $400,000, five-year NSF Career Award and a $300,000, three-year Young Investigator Award from the Office of Naval Research (ONR). Both honors are the top awards given to young faculty by those agencies. ONR gives only 24 such awards each year.
Developing Robots Real-World Skills
Stilwells goals are to develop control laws so that autonomous vehicles can solve problems cooperatively. Many researchers have been working to develop cooperating autonomous robots, he said, but there is often a gap between theory and practice. We are developing theories of robot cooperation, and we require that our results work in the real world, and not just the laboratory, he explained.
Tracking the Tide
Stilwells real-world environment will include the coastal waters of Hog Island Bay on Virginias Eastern Shore and the York River where it meets the Chesapeake Bay. For the NSF Hog Island Bay experiments, the AUV platoon will track and measure dissolved oxygen over a large area of the bay and along a moving tidal front over a one to two hour period. The platoon will also detect and map any freshwater seepage at the bottom of the bay.
Marine Scientists to Use Data
Marine scientists will use the dissolved oxygen measurements to estimate metabolism of the bay and determine the health of the estuary system. Ultimately, scientists hope that the data will enable them to determine fate of nitrogen from agricultural and urban runoff. Understanding exactly how nitrogen is buffered in a coastal estuary is critical for understanding the role of man-made pollution in the oceans and coastal watersheds, Stilwell said.
Mapping and Tracking
In the ONR York River project, the AUV platoon will be used to develop mapping and tracking methods in four dimensions (space and time) for underwater sensor networks, mine countermeasures, and wide-area search and survey tools. The energetic environment of the tidally-driven York River presents a challenging unstructured environment in which to address communication, navigation, and cooperation issues.
The experiments are highly complementary, Stilwell said. The Hog Island Bay project seeks to determine best practices for controlling the coordinated motion of cooperating AUVs once it has been determined where they should go. The York River project seeks to determine where they should go.
The VT Miniature AUV
Stilwells projects rely on a fleet of low-cost miniature AUVs that his team is building. The Virginia Tech AUVs are the smallest known fully functional underwater vehicles to be developed to date, yet the cost for components is less than $2,000. They navigate using a custom-engineered miniature inertial system, miniature single-beam altimeter, and single-beam forward-looking sonar. When surfaced, they utilize GPS for precise positioning and communicate via a radio modem.