For most people, when they think of what firefighters do, the images of them putting out fires and saving people is what comes to mind. However, in many communities, one of the most important annual tasks the fire department will do is actually start fires. Controlled fires or prescribed burns are one of the best tactics for the prevention of out of control wildfires. From 2019 to 2020, the world faced its most devastating wildfire seasons in history. In Australia, the 11 months long fire season became known as the Black Summer. More than 18.6million hectares of land were burned, taking the lives of at least 34 people, and billions of creatures unique to the continent. In California, nearly 4% of the state, almost 2million hectares of land, were destroyed by wildfires. More than 10,400 buildings were lost, and 31 people died.
Fires have always been natural ways that a forest ecologically controls itself. But as populations have increased and global temperatures have risen, these fires have become more frequent, intense, and deadly. In a prescribed burn, firefighters will create a fire line to burn back overgrowth that could lead to a wildfire. The fires are lit along previous paths that reinforce a natural wildfire border and encourage healthy regrowth. Firefighters start the fires by hand with specially designed torches. These driptorches are designed to allow the firefighter to control the exact location of the fire while staying at a relatively safe distance. Having to light fires by walking with the driptorch in hand, or mounted to an ATV is still very risky for people. Another option is to implement a prescribed burn from a small plane or helicopter. However, using a manned aircraft is not only extremely expensive, but it also is not always accurate.
After completing his Ph.D. at MIT, Carrick Detweiler became the Susan J. Rosowski Associate Professor in the Computer Science and Engineering Department at the University of Nebraska-Lincoln. He also became the co-founder of the NIMBUS (Nebraska Intelligent Mobile Unmanned Systems) Lab, where as he states, “My research interests include field robotics, environmental monitoring, agricultural robotics, adaptive sampling, perception, localization, and safety and reliability of robots in the wild. I work with and build everything from flying robots to underwater sensor networks and often explore the boundaries between robots and sensor networks. My goal is to develop systems and algorithms that enable robots to operate in real world conditions to aid scientists, farmers, and others.” One of these research projects led Carrick and his colleague Sebastian Elbaum, Professor of Computer Science and Engineering, to look for a way to use drones to safely and successfully carry out prescribed burns.
The original drone Carrick and Sebastian designed was called the AscTec, a six-rotor, 1sq meter drone that could easily fit in a backpack. With a range of sensors, the pilot can precisely drop ping pong sized balls that would ignite controlled fires. The balls are filled with an ignition chemical and loaded into a chute atop of the drone. The chute can hold about 15 balls. Just before the drone releases a single ignition ball, a second chemical is injected into the ball. Moments after the ball lands, it ignites and safely starts a controlled fire. A detailed flight plan is programmed into the drone that corresponds with the firefighter’s goals. “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,” Sebastian 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.” The drone can drop the ignition balls above the tree line or lower to the ground to ensure the balls stick their landing in uneven terrain.
After successfully testing the AscTec with the support of the FAA and local fire agencies, it was time to scale up operations. Sebastian eventually went on to teach at the University of Virginia and Carrick, who is still at the University of Nebraska-Lincoln, founded Drone Amplified to perfect the prescribed burn drone. With Drone Amplified, Carrick “amplifies” existing drones like the DJI Matrice 600 with the IGNIS, a complete system that embeds with the host drone. IGNIS relies on the original idea behind AscTec but suped up. First, the IGNIS hopper securely connects with thumb screws beneath the drone and can hold up to 150 ignition balls. Then IGNIS is electrically connected to the drone to allow the system to seamlessly communicate. Next, the dropper mechanism is physically and electrically attached below the hopper. The last step in preparing the IGNIS is to install the battery and connect the power lead so the system can run its automated calibration and safety checks.
Once the IGNIS is fully calibrated, the ignition balls are loaded into the hopper and the secondary propellant, antifreeze, is added to the reservoir on the dropper system. The system can drop 30 ignition balls per minute. With a drone that has an average 30 minute flight time, IGNIS can cover 50-75 acres of land in a single payload. The ignition balls can be dropped in unique patterns that, as Drone Amplified states, “can only be achievable from an aerial vehicle.” IGNIS still needs to be managed by a firefighting ground team, just like any prescribed burn. But with the drone system, firefighters can safely and efficiently cover far more ground. Wildfires are bound to happen, but when firefighters are given the right tools to manage natural environments, they have the chance to mitigate the damage these fires can inflict. Drones have been instrumental in the planning of fire rescue missions. Now, they can be used to prevent uncontrolled fires as well.