Phys.org—Robotics researchers in Spain and the U.S. are studying bats for their design work on drones. Bat wings are highly articulated, with skeletons similar to those of human arms and hands. The researchers have built a drone that mimics the way a bat changes its wing shape in flight. Bats achieve an “amazing” level of maneuverability, says a researcher, mainly because of their capacity of changing wing morphology during flight. Specifically, the "Batbot" replicates the way a bat changes the profile of its wing between the downstroke and upstroke. By folding wings toward their bodies on the upstroke, bats use 35 percent less energy and reduce aerodynamic drag, according to researchers at Brown.

The interest in bats is because of the way bats change the shape of their wings, which has potential for improving the maneuverability of these air devices. Julian Colorado and colleagues at the Polytechnic University of Madrid, Spain and at Brown University in Providence, Rhode Island, built the drone with an end goal in mind—more agile, autonomous robots making more agile moves than can fixed wing aircraft.

Colorado said that trying to mimic that level of functionality requires analysis of bat flight and novel technologies, ranging from design to control issues. Colorado’s team refers to their device officially as the “BaTboT” robot. They make use of shape memory alloys as muscle like actuators, behaving as biceps and triceps along the wing-skeleton structure of the robot.

The wing extends and contracts under the control of the shape-memory alloy wires that switch between two shapes when different currents are applied. The wires, between the "shoulder" and "elbow" of the robot, rotate the elbow, pulling in the "fingers" to slim the wing profile on the upstroke. This contracts and extends the wings in a similar way to the biological counterpart, said Colorado.