Virginia Tech researchers at the Center for Marine Autonomy and Robotics have partnered with Boston-based Dive Technologies, a subsea robotics designer and manufacturer, to support the development and testing of a novel autonomous underwater vehicle with a new vehicle design, and state-of-the-art control, software, and autonomy systems.
This multiyear collaboration provides an opportunity to apply research discoveries and innovative technology developed in the academic lab and deploy them in next-generation commercial applications.
"The structure of this partnership is so inspiring and embodies everything we’re working to enable through the LINK LICENSE LAUNCH discovery to market team,” said Brandy Salmon, Virginia Tech’s Associate Vice President for Innovation and Partnerships. “Through a sponsored research agreement and customized license, Dive Technologies and Virginia Tech are collaborating to develop cutting-edge autonomous underwater vehicle (AUV) technologies. This gives Dive the opportunity to further commercialize, manufacture, and scale their innovative AUV platform. This end-to-end approach creates value on both sides and ensures technologies developed at the university deliver societal and economic impact. We look forward to supporting our researchers and Dive as the work advances."
The interdisciplinary research team at Virginia Tech is led by Daniel Stilwell, Professor in the Bradley Department of Electrical and Computer Engineering, and Stefano Brizzolara, Associate Professor in the Kevin T. Crofton Department of Aerospace and Ocean Engineering. Together with their team of graduate students, they are combining years of research and expertise in marine hydrodynamics and propulsion, with state-of-the-art autonomous control systems and software.
“Dive Technologies came to us with a specific set of requirements for their unmanned underwater vehicle, which will perform deep ocean surveys and data collection,” said Stilwell. “As one of the only places in the country that is comprehensively studying autonomous underwater vehicles, Virginia Tech is helping them leap ahead in terms of technology.”
Stilwell’s team is providing all of the vehicle’s software, which includes the autopilot, autonomy functions, and a graphical user-interface that the operator uses to program a mission.
“The software we are providing has been largely vetted here at Virginia Tech on our own unmanned underwater vehicles,” said Stillwell. “This work has the potential to advance the industry in terms of the capabilities of underwater vehicles.”
Creating the optimal design
Brizzolara and his team have been working on improving the vehicle design to enable long endurance missions. Through computational modeling and sophisticated hydrodynamic studies, they are collaborating with Dive Technologies to develop a design that helps reduce drag and improve the propulsion efficiency of the vehicle. With a more efficient design, the vehicle is more maneuverable and has the ability to cover longer distances.
Specifically, Brizzolara and his team are exploring solutions to minimize the drag of the hull at cruise and survey speeds.
“Using high fidelity computational fluid dynamic models able to accurately model the transition between laminar and turbulent flow, we are able to resolve the steady and unsteady flow around the vehicle,” said Brizzolara. “This includes the propellers and fixed and movable appendages for motion control. Virtual model tests, based on the numerical models, are then used within design optimization algorithms to find the best combination of hull and appendages geometry as well as propulsion system, often resulting in novel shapes and configurations.
“In the case of Dive Technologies’ vehicle, these novel design paradigms have led to an increase in the maneuvering abilities, through specific design choices based on a novel, high-fidelity maneuvering model and a particular design of the hull shape with compliant surfaces, which guarantees a very low drag coefficient,” Brizzolara added.
The research team has also provided a custom design for the vehicle’s propulsion and investigated the best size and location placement of the propeller in the stern of the vehicle.
“Optimizing propeller design to account for proper hull interaction and allowing for a change not only in propeller diameter but also longitudinal position behind a vehicle is a novel concept, which has shown significant improvements of the overall propulsion efficiency,” said Brizzolara.
The first prototype of the large displacement unmanned underwater vehicle, which measures about 18 ft (5.4 m) long, is currently under construction at Dive Technologies and is on schedule for sea testing this summer. The team at Virginia Tech will continue to work for another two years and use the test data to continually improve the control systems and the hydrodynamic design and refine the propulsion systems.