Researchers developed Midair's reconfigurable quadcopter drones that can be passive as needed

According to New Atlas, quadcopters may be versatile drones, but the four rotors do make it impossible for them to perform certain tasks. An experimental new drone solves this shortcoming, and its rotor can be passively folded up as needed.

First of all, we have seen before that quadcopters can be reconfigured in flight, although they are done with electric pushers. This means that their ability to "deform" drains battery power and increases the complexity of the electrons.

Seeking a simpler alternative, scientists at the HiPeRLab at the University of California, Berkeley, have developed what they call the Midair Reconfigurable Quadcopter drone, which uses unpowered hinges. More simply, this means that only gravity or reverse thrust is needed to flip each of its rotors down as needed.

This setup makes many maneuvers possible. For example, if a horizontally flowing drone needs to squeeze through a narrow vertical opening, it will reverse the thrust direction of the two opposing rotors, causing them both to fold down. Since the thrust axes of these rotors cancel each other out (the drone's fuselage is rectangular, not square), the yaw torque they produce cancels out the yaw torque generated by the other two rotors.

As a result, the folded drone is able to pass through the opening smoothly and stably. Since the two folded rotors are actually pushing and shoving each other, they can also grab it by pinching a flat box from either side. The box can then be lifted, fly in the air, and released in another place.

In addition, if a hovering drone needs to descend through a narrow horizontal opening, all four of its rotors will reverse their thrust direction, causing all four rotors to fold. When the drone begins to fall freely, its vertical orientation is controlled by changing the thrust of the rotors relative to each other. Once it passes through the opening, the thrust reverses and returns to its original state. This will cause all the rotors to be lifted again, allowing the quadcopter drone to resume hovering before moving on.

Finally, if the drone needs to stay on the power line, it can be achieved by landing on the power line and then turning off all the propellers. This will cause its four rotors to descend, shifting the drone's center of mass below the point of contact, keeping it balanced on the power line.

Although the Midair reconfigurable quadcopter has recently received publicity, it was first described in a paper published in the journal IEEE Xplore in 2019. The study was led by PhD student Nathan Bucki, assistant professor Mark W. Mueller, and researcher Jerry Tang.