WEB DESK: For decades, scientists have been trying to create machines that mimic the way birds fly. A team from Stanford University has gotten one big step closer.
The team created the PigeonBot — a winged robot that it says approximates the graceful complexities of bird flight better than any other robot to date.
When a bird is soaring through the air, it dramatically changes the shape of its wings as it makes hairpin turns and swoops up and down. Birds change the shape of their wings far more than planes do, and the complexities of bird flight have posed a major design challenge for scientists trying to translate the way birds fly into robots.
Ultimately, the motions that bird wings make are seen as far superior to those of an aircraft: “It actually enables birds to fly further, longer, maneuver much better,” says David Lentink, a professor of mechanical engineering at Stanford University. “I really love aircraft as well, but it just doesn’t compare to a bird.”
Lentink led a team to try to pinpoint some of the unique ways that bird wings work. The researchers then used what they found to create the PigeonBot.
The researchers used common pigeon cadavers to try to figure out the mechanics of how birds control the motion of their feathers during flight. Scientists had thought the feathers might be controlled by individual muscles. But they learned that some aspects of bird wing motion are simpler than they expected.
Lentink says that several doctoral students realized that simply by moving a bird’s “wrist” and “finger,” the feathers would fall into place. When the bird’s wrist and finger move, “all the feathers move too, and they do this automatically,” he said. “And that’s really cool.”
The findings are some of the first evidence that the bird’s fingers are important for steering. The team replicated the bird’s wing on the PigeonBot using 40 pigeon feathers, springs and rubber bands connected to a wrist and finger structure. When the wrist and finger move, all the feathers move too.
The researchers used a wind tunnel to see how the feather-and-rubber-band design worked under turbulent conditions. “Most aerospace engineers would say this is not going to work well, but it turned out to be incredibly robust,” Lentink says.