CalTech engineers develop bird-herding drone

Engineers at CalTech have taught a drone how to herd a flock of birds out of airport airspace to reduce the chances of bird strikes on manned aircraft.

Researchers at the university’s Center for Autonomous Systems and Technologies in Pasadena, California, developed a control algorithm that manages the flock as a single, contained entity—keeping the birds together while shifting their direction of travel. Piloted drones proved too unreliable for the task. The algorithm is presented in a study in IEEE Transactions on Robotics.

The project was inspired by the 2009 "Miracle on the Hudson," when US Airways Flight 1549 struck a flock of geese shortly after takeoff. Pilots Chesley Sullenberger and Jeffrey Skiles were forced to land in the Hudson River off Manhattan in New York.

"The passengers on Flight 1549 were only saved because the pilots were so skilled," says Soon-Jo Chung, an associate professor of aerospace and the principal investigator of the project. "It made me think that next time might not have such a happy ending. So I started looking into ways to protect airspace from birds by leveraging my research areas in autonomy and robotics."

Current strategies for controlling airspace include modifying the surrounding environment to make it less attractive to birds, using trained falcons to scare off flocks or deploying a drone to scare the birds. Chung said these strategies can be costly or—in the case of the piloted drone—unreliable.

"When herding birds away from an airspace, you have to be very careful in how you position your drone,” he said. “If it's too far away, it won't move the flock. And if it gets too close, you risk scattering the flock and making it completely uncontrollable. That's difficult to do with a piloted drone."

Bird herding by drone relies on the ability to manage the flock by keeping it together while shifting its direction of travel. Each bird in a flock reacts to changes in the behavior of the birds nearest to it until the entire flock changes course. If the external threat gets too zealous and rushes at the flock, the birds will panic and act individually, not collectively.

"We carefully studied flock dynamics and interaction between flocks and pursuers to develop a mathematically sound herding algorithm that ensures safe relocation of flocks using autonomous drones," says Kyunam Kim, postdoctoral scholar in aerospace at Caltech and a co-author of the IEEE paper.

The team tested the algorithm on a flock of birds near a field in Korea and found that a single drone could keep a flock of dozens of birds out of a designated airspace. The effectiveness of the algorithm is only limited by the number and size of the incoming birds, Chung said, adding that the team plans to explore ways to scale the project up for multiple drones dealing with multiple flocks.