Researchers at the University of Groningen have designed a drone with legs that feature four 3D-printed talons. Inspired by the peregrine falcon – an apex predator that uses its talons to grasp prey – the Stereotyped Nature-Inspired Aerial Grasper (SNAG) is able to perch just as birds do.
“Everything is a landing strip for a bird,” says David Lentink, coauthor of the study. “To us, this is really inspiring: The whole idea that if you would just design different landing gear, you might be able to perch just anywhere.”
Upon contact with a branch, SNAG starts to fold in upon itself. A “tendon” in the leg lengthens, gathering tension until a quick-release mechanism triggers a spring to create the grasp force. The claws and toe pads on the “talons” aid in helping SNAG hold on tightly. The drone’s legs are able to convert the energy of its impact with the branch into grasping energy in just 50 milliseconds.
“The robot has momentum—it’s not like a helicopter landing,” says Lentink. “It’s a dynamic landing, a controlled collision.”
An accelerometer is used to check the drone’s balance, with motors in the “hips” making corrections to its posture when necessary. To release the grip and then fly away, another motor decreases the tension in the tendon causing the digits to automatically curl back to the open position.
Future research will work on making SNAG autonomous – it is currently guided by a pilot with a remote-control. The team will look at enabling SNAG to localize a branch, calculate how to approach it, and make the landing independently. They are also examining the possibility of SNAG using its grasping ability to hunt other drones, just like the falcon which inspired its design.