A research team at Florida Atlantic University's (FAU) College of Engineering and Computer Science has received a $187,000 grant from the Florida Department of Transportation (FDOT) to develop autonomous waterborne vehicles that can assist in bridge inspections. Though the technology is still early in the research phase, said principal investigator and FAU professor Karl von Ellenrieder, the long-term hope is that these vehicles might be used by the state to make the job of bridge inspectors safer and more efficient.
“These sorts of technologies aren’t really meant to replace wholesale divers and so forth,” von Ellenrieder said. “It’s to make their jobs easier, and it’s another tool that can help them do their jobs better. The way I view it is you would take a vehicle like this and it would allow you to more rapidly scan bridges, and then when you detect a problem, send out a diver to verify the problem [through testing].”
Today divers are the only method FDOT uses to biennially inspect and test the state’s 11,451 bridges. The role of bridge inspectors is to search for cracks, erosion, damage and defects that might impact the bridge's safety. The idea, von Ellenrieder said, is to make drones do the dirty work before sending in people.
“If you’re going to send divers out into strong currents with nasty snakes and stuff, it’s better to have a good sense there’s a problem before you do that,” he said.
The team, now two months into a 12-month project, has so far upgraded a watercraft used for past research projects with a new propulsion system that allows the craft to maintain its position and heading during a bridge scan. The next phase of research, von Ellenrieder said, will be to equip the craft with an acoustic scanning system that functions similar to a lidar system. By installing the scanner on a mount that can tilt and pan, researchers expect to obtain 3-D models of the parts of the bridge that are under water.
“This is a way to make the initial part of that search safer for people, to do it more quickly, to get quantitative results instead of qualitative results and to basically empower them to make better decisions where they use their resources,” von Ellenrieder said.
The water drone is equipped with an automatic control system that uses GPS and a compass to direct the craft toward programmed waypoints. Once the acoustic scanner is equipped in September, von Ellenrieder said, the team will begin testing the craft’s scanning capabilities on three bridges — one at Port St. Joe, the Highway 20 bridge on the Apalachicola River and the Garcon Point Bridge — sites recommended by FDOT for their diverse representation of the state’s many bridge environments.
“There are multiple efforts going on,” von Ellenrieder said. “One of them is we’re doing a fairly extensive literature survey to understand what sorts of technologies we can bring in and how to implement this at a larger scale and in more detail in the future, because instead of having one vehicle go in, you probably want to make it so it’s like a team of people and vehicles, and that requires a bit of development on the autonomy side of things.”
The research is intended also to be a proof of concept, he said — once this research is done, it will be clearer what type of imagery is possible, and that information can lead to a more detailed study that will precipitate future advances in autonomous vehicle technology.
According to 2009 data from the Federal Highway Administration, 11 percent of the nation’s 68,842 bridges are “structurally deficient” and require rehabilitation, replacement or maintenance that would cost $70.9 billion. With physical infrastructure funding lagging behind this backlog, advances in drone technology might give bridge inspectors and repairers the boost they need to ensure the safety of America’s drivers.
