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Holy flight plan: Researchers build a robotic bat wing

Image of robobat and bat wing
A robotic bat wing lets researchers measure forces, joint movements, and flight parameters — and learn more about how the real thing operates in nature.Breuer and Swartz labs / Brown University

A robotic bat wing flapping in a university lab is providing researchers with a new appreciation for the wonders of nature and hints at a new generation of mini flapping planes to be deployed on reconnaissance missions.

The robot is modeled after the lesser dog-faced fruit bat and flaps while attached to instruments that measure the forces generated by various joints, allowing the Brown University researchers to calculate the energy required to execute wing movements.

"A lot of my interest in bat flight is in understanding how they fly and in particular how their wing motion influences their aerodynamic force generation," Joseph Bahlman, a graduate student at the university who led the robotic bat project, told NBC News.

The problem is that studying wing motion in live bats is difficult since bats change several parameters at once depending whether they want to fly slower or faster, turn one way or another, or any other aerial maneuver.

"The solutionto that was to build a robotic bat wing that I can then systematically control the motion parameters," Bahlman said.

While detailed experimental results are forthcoming, a case-study experiment showed that by folding the robotic wing on the upstroke, as real bats do, the robot is able to increase net lift by 50 percent.

This type of data could aid the design of small flapping aircraft for recon missions. "Things that are a foot, foot and a half wingspan that you can send into places that aren't safe for people like abandoned mine shafts or to inspect weak spots around bridges," Bahlman said.

Building the robot, Balhman added in a news release, taught the team many lessons “about how bats work from trying to duplicate them and having things go wrong.”

For example, the joint used to build the robot’s elbow kept ripping apart during test flights, forcing the researchers to wrap it steel cable similar to the way ligaments hold joints together in animals. Real bats, it turns out, have large muscles at the elbow that help prevent the joint for breaking.

Going forward, the team aims to test out different wing materials, aiming to optimize their design. For example, Bahlman told NBC News he wanted to compare a stretchy membrane like a live bat wing with a non-stretchy material. He suspects the stretchy skin of bat wings enhances flight performance.

"There are just tons of questions," he said. "This made for just a really powerful research tool."

If this research is ultimately paired with other bat-inspired technology, such as an echolocation-based navigation tool that recently allowed a blind college to ride a mountain bike, future robots will be quite batty indeed.

A paper describing the robot was published in the journal Bioinspiration and Biomimetics.

John Roach is a contributing writer for NBC News. To learn more about him, check out his website.