We’ve all seen movies where the hero has to make it through a small gap in an airplane or spaceship, turning it sideways in order to make it thinner on the horizontal plane and squeezing through. While exciting — and likely unrealistic — birds are actually able to do a similar feat by tucking their wings as they hit a gap then unfurling them as they fly out. Now, with the pioneering work by French researchers, the “Quad-Morphing” quadcopter can do the same thing, folding its rotors from an “I” configuration into a line the width of an individual rotor.
The trick to this system is a high-speed servo motor in the middle of the frame, along with a linkage system consisting of flexible and rigid members. This servo pivots the motors into a straight line momentarily, then pops everything back out on the other side to restore normal flight characteristics.
Control for the Quad-Morphing is accomplished via a Gumstix Overo Linux-based computer-on-module, along with a NanoWii board carrying a six-axis internal measurement unit (the familiar MPU-6050). A custom rotor control board is also implemented for low-level control of the propeller rotational speed and to provide connections.
You can see a video of the aerial robot altering its arms to fit through a tight space in the project’s write-up.