Changing Course for UAVs

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Ohio State electrical and computer engineers have solved a radar and surveillance problem for unmanned aerial vehicles (UAVs) with the help of atypical collaborators: embroidery experts.


Game Changers
This research is part of the three-year, $3.5 million GameChanger program, now in its final year and funded by the Air Force Defense Research Sciences Program.The UAVs — ranging in size from more than 40 feet long to ones that could be easily confused with hi-tech Frisbees — can serve many functions, from surveillance to data collection. However, their relatively small size cannot accommodate the large antennas necessary for long-distance communication. So the engineers are developing new technology to weave sensor and communication antenna systems into the structure of the UAVs.

The GameChanger philosophy involves a different perspective on aircraft design: Instead of mechanical and aerospace engineers designing a plane for aerodynamics, in this case electrical and computer engineers dictate the initial form of the plane based on its radar or surveillance function.

To weave the sensor and communication systems into the structure of the aircraft — so the UAV itself becomes the antenna — researchers needed lightweight, load-bearing, flexible materials that could conform to the aircraft’s surface. Polymers fit the required criteria, but first researchers had to determine how to print antennas on them, as polymers are not mechanically compatible with traditional conductors.

“It sounds simple, but we didn’t have a design methodology and didn’t know how the radio frequency would react in new, untested materials such as polymers,” says electrical and computer engineering Professor John Volakis, who leads the GameChanger research efforts.

Researchers from the ElectroScience Laboratory solved the challenge by developing a process for embroidering electrically conductive fibers onto polymer substrates. This required researchers to learn an unexpected skill: sewing.

“It turns out that sewing is not as easy as it appears,” says Yakup Bayram, a senior research associate leading the e-fiber research. “We spent months working with local embroidery experts to learn how to embroider the e-fibers correctly so the threads could withstand the frictions of the embroidery machine.”
Researchers also developed an automated process to ensure a smooth transition of the technology from the laboratory to industry.

“Once an engineer designs an antenna using traditional software, that design is transferred to a digital format that can be recognized by embroidery machines,” says Bayram. “In order to apply the design to a UAV, an aircraft skin is first made out of a structurally reinforcedpolymer substrate. Then, an industrial sewing machine can embroider the design directly onto a piece of the aircraft, such as the wing.”

Syscom Advanced Materials, a local start-up company, supplied the e-fibers, made of silver-coated, high-strength Zylon. In return, this research provides a new application for the company’s e-fibers in the aerospace industry.

“This is a low-cost approach, which is important because in the future, UAVs will be made by the thousands,” says Volakis.
Ohio State mechanical engineers are developing simulation tools to test how the new technology will perform under the extreme conditions in which UAVs fly. Meanwhile, materials science researchers from the University of Michigan are exploring techniques to make the e-fibers even more conductive and stronger, and researchers at the Universities of Minnesota and California-Los Angeles are working to further miniaturize antennas.

Candice Clevenger is public relations coordinator for the Department of Electrical and Computer Engineering and the ElectroScience Laboratory.

Contact:

John Volakis, (614) 292-5846, volakis.1@osu.edu