Engineers from Stanford University created a robot that can grasp irregular objects.
The robot, called Stereotyped Nature-inspired Aerial Grasper (SNAG), is inspired by peregrine falcons, which is the fastest animal on earth reaching 200 miles per hour (320 km) when diving.
Studying how the peregrine falcons catch their prey with their claws at high speeds and how they grasp objects when they land, Mark Cutkosky and David Lentink from the University of Groningen in the Netherlands enabled multirotor drones to land on different surfaces instead of flat objects, as well as grabbing or catching objects in midflight.
Cutkosky Lab studied robots that are inspired by animals and the Lentink Lab studied bird-inspired aerial robots enabled the researchers to build their own perching robot.
“Everything is a landing strip for a bird. 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” says Lentink, co-author of a paper about Snag in the journal Science Robotics, along with Cutkosky and William Roderick.
“It’s not easy to mimic how birds fly and perch,” said Roderick, who was a graduate student in both labs. “After millions of years of evolution, they make takeoff and landing look so easy, even among all of the complexity and variability of the tree branches you would find in a forest.”
With its motors acting like muscles in the falcon's legs, SNAG absorbs the landing impact and its wires that act like tendons help the claws to snap shut around the perch in less than half of a second. “The robot has momentum—it's not like a helicopter landing,” says Lentink. “It's a dynamic landing, a controlled collision”. After claws grab the object or surface, the ankles lock. When the accelerometer registers that the robot has come to a stop, a balancing algorithm stabilizes the robot using the motors in the hips. SNAG releases its grip by decreasing the tension in the tendon and releasing the claws back to the open position and flying away.
During the tests in a forest, SNAG was able to land and hold onto branches even when the branches were slippery.
Enabling drones to “rest” on various surfaces, researchers say that the battery range of drones can be extended without the need of landing and ascending again.
SNAG is also able to catch objects thrown at it with its responsive claws.
Cutkosky and Lentink designed SNAG primarily as a platform to monitor rainforest ecosystems. The duo envisioned it as a mobile camera trap, to monitor wildlife or as a wildfire early-warning system.
Lentink also pictures SNAG as a drone hunter. “If you think about airport problems, for example, where Heathrow has been shut down because there was a drone nearby, it would be useful to actually capture another drone without having to shoot it down,” he says.