Researchers build robotic bat wing

The swift turning flight and aerodynamics of bats offers amazing possibilities for the design of small aircraft, among other applications. By building a robotic bat wing, researchers at Brown University have uncovered the flight secrets of real bats: the function of ligaments, the elasticity of skin, structural support of musculature, skeletal flexibility, upstroke and downstroke.

Tests showed the machine can match the basic flight parameters of bats, producing enough thrust to overcome drag and enough lift to carry the weight of the model

species.

A paper describing the robot and presenting results from preliminary experiments is published in the journal Bioinspiration and Biomimetics. The work was done in labs of Brown professors Kenneth Breuer and Sharon Swartz, who are the senior authors on the paper. Breuer, an engineer, and Swartz, a biologist, have studied bat flight and anatomy for years.

The faux flapper generates data that could never be collected directly from live animals, said Joseph Bahlman, a graduate student at Brown who led the project. Bats can’t fly when connected to instruments that record aerodynamic forces directly, so that isn’t an option — and bats don’t take requests.

"We can’t ask a bat to flap at a frequency of eight hertz then raise it to nine hertz so we can see what difference that makes," Bahlman said. "They don’t really cooperate that way."

But the model does exactly what the researchers want it to do. They can control each of its movement capabilities — kinematic parameters — individually. That way, they can adjust one parameter while keeping the rest constant to isolate the effects. This data will not only give new insights into the mechanics of bat flight, it could aid the design of small flapping aircraft or "micro aerial vehicles".

"The next step is to start playing with the materials," Bahlman said. "We’d like to try different wing materials, different amounts of flexibility on the bones, looking to see if there are beneficial trade-offs in these material properties."

The research was funded by the U.S. Air Force Office of Scientific Research and the National Science Foundation.