Ranchers who use prescribed burns to control invasive plant species on their pastures could soon receive some help from above.
Researchers at the University of Nebraska-Lincoln have developed a prototype unmanned aerial vehicle — commonly called a drone — capable of safely igniting prescribed burns.
Developed at UNL’s Nebraska Intelligent Mobile Unmanned Systems (NIMBUS) lab, the six-rotor AscTec “micro-drone” is only about 1 square foot in size, capable of fitting into a backpack. The drone has various layers of sensors, systems and software which enable an operator to very precisely and safely ignite a prescribed burn, according to Sebastian Elbaum, professor of computer science and engineering at the University of Nebraska-Lincoln.
Elbaum and Carrick Detweiler, assistant professor of computer science and engineering, designed the prototype for the drone, which was delivered quickly by a highly qualified manufacturer.
HOW IT WORKS
The drone carries small balls that contain a chemical powder. Just before dropping the ball, the drone injects a second chemical into the ball and it bursts into flames within 60 seconds. The drone is capable of dropping the fireballs every few seconds, Elbaum said.
The UNL team has four prototypes of the drone, each carrying different sensors, a different number of fireballs and even different types of balls. While the current vehicles carry anywhere between 15 and 75 balls, the next prototype may be able to carry twice as many.
As the balls ignite, fire begins to emerge. Since the drone is a robot of sorts, users can plan very precisely where they want the fireballs to land.
“You can program where they are going to fall, or you can specify patterns where you want them to fall every ‘x’ number of feet over an area,” Elbaum said. “You can actually tell them to go in a line or circle. You can specify all kinds of fire patterns that would be hard to do with a person.”
Another benefit of the drones is that they can fly very low, so the balls are not blown away by wind gusts. The current prototypes are capable of flying in winds up to 15 miles per hour, but with prescribed fires manned by people, the winds are usually only up to 10 mph in Nebraska.
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Currently, most people doing prescribed fires in small- and medium-sized areas are using tools such as torches, which haven’t changed in the last 20 to 30 years, he said. Cars and all-terrain vehicles are also commonly used, which work well when there are roads or paths to navigate, but become more dangerous in rugged terrain such as ravines or canyons.
“That’s where we think these micro-drones can come in. They can actually reach hard areas and cover them fast,” Elbaum said. “They can get to a target location and initiate fires in a very controlled and targeted manner.”
Earlier this spring, the NIMBUS team tested their drones to ignite a prescribed burn of more than 2,000 acres of private land in a loess canyon area near Gothenburg, Nebraska, in the south-central area of the state.
The goal of the burn was to target the red cedars that are considered an invasive species and are a problem because they consume a lot of water and take up a lot of pasture space, Elbaum said.
Then, in April, the NIMBUS team used the drone to burn 26 acres of restored tallgrass prairie at the Homestead National Monument of America near Beatrice, Nebraska, where a third of the prairie grass is burned every year for soil health and to control invasive species.
“It was a great test,” Elbaum said. “We were able to work with firefighters, learn about how the technology performed, learn what the firefighters liked and didn’t like, which helped us learn what aspects of the technology were limiting.
Other collaborators in the Homestead prescribed burn included the National Park Service’s Midwest Region Fire and Aviation Program, the Service’s national-level Branch of Aviation; and the Department of the Interior’s Office of Aviation Services.
The Federal Aviation Administration gave permission for the test after the device was reviewed and approved by the National Aeronautics and Space Administration, which oversees air transportation research as well as space research.
After analyzing data from the Homestead burn, Elbaum said one of the interesting things the team learned was fire vectors and temperature information. This will help them to assign paths that are safer to navigate and gave them a better idea of the efficiency of the vehicle and the success rates of the initiated fires.
Since the tests, the team has been contacted by other parks interested in doing prescribed burns with drones, as well as ranchers in Nebraska and Kansas, and people in Michigan, Georgia and Arkansas, to name a few.
The drones could also be used to combat wildfires.
The NIMBUS team is talking to the Department of the Interior and private organizations to try to work with them in a more systematic way for conducting trials and to help them learn how to develop the technology to better match current needs, Elbaum said.
He summed up the team mission in three goals: to push the technology as far as possible to solve large problems, to help students become educated in the design and use of complex systems, and to perform outreach to help people doing this type of activity in the field.
REGULATIONS AND TRAINING
Firemen or others using the drones will need to be trained, though the main goal of the team at UNL is to minimize the amount of training that is needed by programming the vehicle to operate on autopilot most of the time.
The Federal Aviation Administration requires even small drones to be registered, but since the NIMBUS engineers are not recreational users and are not doing things with drones that recreational users do, they needed a special Certificate of Authorization from the FAA to conduct their tests.
Elbaum said the laws for drone registration and usage are changing rapidly and may become more streamlined and straightforward in the future.
Other members of the NIMBUS team who helped develop the drone were Craig Allen, UNL professor and expert on invasive species management and sustainability; Dirac Twidwell, UNL rangeland expert who studies prescribed burns; Brittany Duncan, assistant professor of computer science and engineering; and students James Higgins, Evan Beachly, Christian Laney and Rebecca Horzewski.
Cheryl Anderson can be reached firstname.lastname@example.org
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