Engineers from UC Berkeley’s HiperLab have designed a novel drone that can fly through windows using collapsible (or morphing) arms. This isn’t the first drone to have morphing capabilities though, as engineers from the University of Zurich designed a foldable drone that’s outfitted with servomotors that can retract its arms collectively, or independently, allowing it to fly in tight spaces. Unlike UZH’s drone, HiperLab’s Passively Morphing Quadcopter uses spring-loaded arms, enabling it to shrink itself by 50% in less than a second when the propellers produce a low-thrust force.
The engineers designed the drone with those springs in constant tension on the passively hinged arms, which is enough to collapse the arms inward when the motors are turned off, and when those motors engage, the force is strong enough to snap the arms back into a rigid open position. The tension points of the springs can be calibrated so that the drone maintains a flight mode for most of the time, and morph only when it needs to.
As you can see in the video, the drone was demonstrated in a controlled setting where its route and trajectory were predetermined with its approach, fold, unfold, and back into flight mode. This means that it has no level of autonomy and requires a human controller to pilot the drone; however, it should fly with no problem as long as the pilot can maintain a visual of the area. The engineers feel they could further reduce the drones folded configuration in future models by letting “the disks swept by the propellers to intersect in the folded configuration,” meaning if they kept the speeds of each propeller at the same rate, there would be no or little chance of the blades hitting each other.