NSF grant unites cross-campus researchers to study and optimize flying robots

UNIVERSITY PARK, Pa. — Researchers in the Penn State Department of Mechanical Engineering recently received a $389,919 grant from the National Science Foundation (NSF) to investigate, explore and innovate new flying mechanisms for micro air vehicles (MAVs) to better mimic the performance and agility of flying animals.

Bo Cheng, assistant professor of mechanical engineering at Penn State University Park, and Azar Eslam Panah, assistant professor of mechanical engineering at Penn State Berks, are aiming to expand the utility of MAVs in gusty environments, which have a growing role in a broad range of civil and military operations, through their project “Unsteady Aerodynamics of Flapping Wings in Gusty Environments: Gust-mitigation Performance, Flow Physics, and Optimization.”

MAVs are unmanned vehicles that share a direct connection in size, speed and flight regime to small birds. They are used for observation of hazardous environments inaccessible to ground vehicles, as well as aerial photography and robotics contests.

“The cool thing about them is they’re so small. They can fly in confined environments, indoors or outdoors, and hover somewhere,” Cheng said.

However, operating in this low-altitude environment means MAVs often encounter natural obstacles like trees or hills, as well as man-made ones like buildings.

“These structures create sharp changes in ambient-flow velocity,” Cheng explained. “When an MAV flies in the wake of a building, it will have an unsteady, turbulent flow. And these flyers aren’t great with dealing with those.”

Bo Cheng, assistant professor of mechanical engineering at Penn State University Park.

While the impact of these flows is largely unknown, in this project, the researchers will look to nature, where birds and insects already mitigate these challenges in a remarkable way.

“We know animals with flapping wings can use them really well, so we want to understand the fundamental benefits of that type of flying mechanism,” Cheng said.

Most research on aerial vehicles has focused on operations in smooth flows, optimizing the design for stable environments.

“But with this project, we are looking at turbulent flows,” Panah said. “We want to look at different categories of flapping wings and understand the physics of them. Right now, drones can fly on mild windy days, but they’re not efficient nor stable.”

The researchers first joined forces in 2016 through a multi-campus seed grant from the College of Engineering focused on fostering cross-campus partnerships.

“That seed grant was really the fuel for this collaboration,” Cheng said.

The project combines Panah’s expertise in fluid mechanics with Cheng’s application in robotics.

“It’s a really good fit for both of our skills,” Panah said. “Through that grant, we were able to gather data for preliminary results for this NSF proposal.”

At the Berks campus, Panah will be simulating the gust environments in a water channel facility she designed and built to study how the gusty flow affects five different types of flapping wings.

“Then, we will see if we can use that data to optimize the flapping motion and develop a drone that can hopefully fly well in that gusty environment,” she explained.

Once the physics of the flapping wings has been determined, the researchers hope to apply machine-learning algorithms to optimize their performance.

“If these MAVs are able to be fully autonomous, they will be able to deal with these flows automatically,” Cheng said.

If so, the use of MAVs can be greatly expanded for military and civilian uses. But gathering that knowledge also represents a significant scientific achievement.

“The results of this research will provide a good foundation of scientific knowledge for flying objects rather than mere intuition, which is often what’s used now,” Panah said.