How this robot pigeon could inspire the future of flight

The researchers looked how birds can dynamically alter the shape of their wings during flight.

(Web Desk) – Researchers from Stanford University have developed a winged robot that mimics the way birds fly and could inspire the next generation of flying robots.

The researchers looked how birds can dynamically alter the shape of their wings during flight, the motions of which are far superior to those of an aircraft.

The "PigeonBot", which features real bird feathers, was developed by Stanford University’s Bio-Inspired Research & Design (BIRD) lab, led by David Lentink, a trained biologist and aerospace engineer.

"An aircraft’s ability to change the shape of its wing is less sophisticated compared with how bats and birds morph their wings continuously in flight," Lentink said in a paper published in Science Robotics.

Rather than flapping, the PigeonBot’s wings use a morphing technique like real bird wings, along with a propeller and tail, like a conventional aircraft.

"Birds morph their wing planform parameters simultaneously - including sweep, span and area - in a way that has proven to be particularly challenging to embody robotically", Lentink describes.

"PigeonBot" features biohybrid morphing wings featuring real bird feathers elastically connected to a pair of robotic bird wings. The joints of the wings can be activated individually.

"Real feathers offer many advantages over our earlier carbon fiber artificial feather designs, because they are softer, lighter, more robust, and easier to get back into shape after a crash by simply preening ruffled feathers between one’s fingers," Lentink explains in the paper.

The team flexed and extended the wings dynamically in a wind tunnel to see how the feathers responded to aerodynamic loading.

They found that bird feathers contain tiny microstructures that form a one-way, velcro-type material that resists sliding in one direction. This is known as "directional velcro".

"Directional velcro" is formed when adjacent feathers slide apart during extension, thousands of lobate cilia on the underlapping feathers lock with overlapping feathers to prevent gaps forming in the wing surface.

Lentink discovered that this ‘nature’s own velcro’ effect is exclusive to certain birds, including bald eagles, California condors and the humble pigeon.

Birds such as barn owls have wings where the feathers can separate, leaving a gap that is less-than-aerodynamic, whereas pigeon feathers include this latch-hook system, keeping the feathers in place.

The team hopes that the morphing ability of PigeonBot could pave the way for creating more agile aircrafts and help shape the future of drone design.