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Thursday, October 27, 2011

The evolution of flight, as performed by robots

How did birds develop flight?  There are two competing theories about this.  First, that birds ran along the ground until, by flapping their progressively more powerful wings, they could finally take off.  Second, that birds glided down from tree branches or other heights, extending their range by flapping their wings.  In each case, smaller less powerful wings would give some advantage even if they didn’t convey actual flight.  So which scenario was more likely?  According to research done by Ron Fearing and his Berkeley students, the second narrative may be the more apt.  And you may be surprised to learn that they draw this conclusion from studying robots.

Fearing and his team added motorized flapping wings to a small six legged robot called DASH (Dynamic Autonomous Sprawled Hexapod).  The original DASH, developed in 2009, was having some problems negotiating inclines and other obstacles.  DASH+Wings was not only more stable and agile, but also much quicker, nearly doubling in speed. You can watch some of the tests below, slowed to 1/10th speed.

What does this have to do with the evolution of flight?  Even with the impressive doubling of ground speed the robot was not able to get air born.  In fact, computer models suggest that to achieve liftoff, an animal would have to triple its running speed.  If DASH+Wings is a reasonable model of a running animal, this data implies that flight could not have developed from the ground up.  That’s a big if though.  Obviously, this question is not settled yet.  However, it’s interesting to think that the question of how flight evolved might one day be resolved by watching robots.