These new capacities could allow flying robots to conserve their batteries instead of having to stand still - for example during operations to search for survivors - or help biologists to take samples more easily in the forest.
"We want to be able to land anywhere, which is why it's exciting from an engineering and robotics point of view," David Lentink, co -author of an article about this innovation published Wednesday in the journal Science Robotics.
As is often the case in robotics, this project was inspired by animal behavior - in this case the way birds land and cling to branches - to overcome technical difficulties.
But imitating these birds, whose millions of years of evolution allow them to cling to branches of different sizes or shapes, sometimes covered with lichen or made slippery by the rain, is not an easy task.
To this end, the Stanford team used high-speed cameras to study how small parrots land on perches varying in size and material: wood, foam, sandpaper and Teflon.
The poles were also fitted with sensors that recorded the force with which the birds alighted and took off again.
Scientists found that while the landing motion was the same in each situation, parrots used their legs to adjust to the variations they encountered.
More specifically, birds wrap their talons around their perches and otherwise use soft, pleated pads to ensure good adhesion.
To be able to support a small drone with four propellers, scientists designed their grippers based on the model of the peregrine falcon's legs.
The structure, made with a 3D printer, includes motors and fishing line as muscles and tendons.
It takes 20 milliseconds for the mechanism to hook up, and an accelerometer then tells the robot that the landing process is complete.
Finally, an algorithm allows the mechanical bird to keep its balance on the branch.
The robotic bird has managed to grab objects thrown at it, such as tennis balls, and land in real conditions in the forests of the northwestern United States.
© 2021 AFP