Back in 2016 we looked at an interesting project out of Switzerland's École Polytechnique Fédérale de Lausanne (EPFL), where researchers had taken inspiration from birds to produce a feathered drone with unique capabilities. The team has continued refining this design to introduce more moving parts, enabling the drone to now fly with “unparalleled agility.”
The version of the drone we looked at a few years ago impressed with its ability to fly quickly, turn sharply and also streamline its body in the face of strong winds. It was able to do this thanks to a set of shape-shifting wings that alter their span and surface area through artificial feathers that can be retracted and expanded, just like those of a real bird.
For their updated version, the EPFL researchers have paired these shapeshifting wings with a morphing tail, which ups the biomimicry even further. This is modeled on the flight behavior of the northern goshawk raptor, which is able to cut through forests and make in-flight adjustments to chase down its prey.
“Goshawks move their wings and tails in tandem to carry out the desired motion, whether it is rapid changes of direction when hunting in forests, fast flight when chasing prey in the open terrain, or when efficiently gliding to save energy,” says Enrico Ajanic, the first author of the study.
The drone uses a propellor for forward thrust rather than its wings, which the researchers say is more energy efficient. Just as it adjusts its wings in flight, the drone can move its tail in tandem to change direction more rapidly, improve its aerodynamics when trying to fly fast, or even to help it slow down without falling to the ground.
“Our design extracts principles of avian agile flight to create a drone that can approximate the flight performance of raptors, but also tests the biological hypothesis that a morphing tail plays an important role in achieving faster turns, decelerations, and even slow flight,” says Dario Floreano, who led the research.
What winged drones like this one offer that quadcopter drones don’t is longer flight times, which makes them well-suited to certain applications such as delivering medical supplies over great distances or surveying farmlands. What they don’t offer, however, is the same hovering capabilities or agility in the air, but the researchers see their solution as something of a happy medium.
“The drone we just developed is somewhere in the middle,” says Floreano. “It can fly for a long time yet is almost as agile as quadrotors. This combination of features is especially useful for flying in forests or in cities between buildings.”
You can hear from the researchers and see the drone in action in the video below, while the research was published in the journal Science Robotics.
Source: EPFL
