The University of Zurich invented foldable drone
At the end of last year, we reported on a foldable drone from the avid Scaramuzza laboratory at the University of Zurich, which can change shape in midair and fly through narrow gaps. The drone uses a servo system to implement its different configuration functions, which makes it very flexible, but at the cost of increasing system complexity and its own weight.
In 2020, researchers at the University of California, Berkeley (UC Berkeley) demonstrated a new design of a foldable drone at ICRA in Montreal.This drone is unmanned because the power of the drone's own propeller controls a spring-loaded weapon. The machine can shrink itself by 50% in less than half a second.
The key to this design is that the spring exerts a constant tension on the passive articulated arm of the quadrotor. When the motor is turned off, there is enough tension to move the arms inward, but when the motor is turned on, they apply a stronger force than the spring, folding the arms again and holding them there. The actual transition point is carefully calibrated to ensure that the quad-rotor drone stays in quad-rotor state most of the time and only folds up when needed.
Researchers have discovered experimentally that the trajectory of the quadrotor is all about approaching, folding, unfolding and recovering, and then aligning the actual window with the trajectory.
Seeing such a folding drone, you might think, why don't you shrink a conventional drone small enough to fit all sizes. The main reason for making drones larger rather than smaller is that they can carry more payloads and stay longer in the air. At the same time, they have more engines that are more distant from each other, making them more stable and better. Ground to resist disturbances such as wind.
The biggest advantage of this design is that it relatively reduces the system complexity of the drone, while still enabling dynamic folding, greatly reducing the size of the drone. And in the deployed state, it is as easy to control as an ordinary quadrotor drone. The researchers also said they might fold the quadrotor drone into a more compact state.