Robotic Winged Bug DASH Reveals Evolution of Flight

Engineers at the University of California, Berkeley, managed to do just that. They equipped a six-legged robotic cockroach with wings in an effort to improve its mobility, but, in doing so, unexpectedly stumbled upon the evolution of flight itself. The Berkley researchers used robot models that could play a useful role in studying the origins of flight to overcome limitations of fossil evidences. 

Adding wings to a robotic bug did help it run faster and better, but they questioned whether it was enough for the bug to take off?

Wings were attached to the 10-centimeter-long robot - called DASH (Dynamic Autonomous Sprawled Hexapod). Scientists found that although the wings provided the extra boost, it did not generate enough speed to launch the critter from the ground.

Scientists observed that the wing flapping also enhanced the aerial performance of the robot, consistent with the hypothesis that flight originated in gliding tree-dwellers.

Published in the journal Bioinspiration and Biomimetics, the research used robot models that could play a useful role in studying the origins of flight, particularly since fossil evidence is so limited, the researchers noted.

The researchers explained that using robot models could play a useful role in studying the origins of flight, particularly since fossil evidence has limitations.

Our overall goal is to give our robots the same all-terrain capabilities that other animals have, said Ron Fearing, professor of electrical engineering and head of the Biomimetic Millisystems Lab at UC Berkeley.

In the real world, there will be situations where flying is a better option than crawling, and other places where flying won't work, such as in confined or crowded spaces. We needed a hybrid running-and-flying robot.

It's still notable that adding wings to DASH resulted in marked improvements in its ability to get around, said Fearing. It shows that flapping wings may provide some advantages evolutionarily, even if it doesn't enable flight.

The engineering team behind DASH+Wings integrated their study with that of Dr. Robert Dudley, a professor of integrative biology and an animal flight expert at UC Berkeley.

Many theories on how animals developed flying abilities had been in vain in the past due to incomplete fossil evidences, so having a wing-equipped robot capable of gliding helped researchers understand how critters first began to fly.

DASH+Wings shows that robots can help confirm computer models and other theories of how animals first began gliding out of trees rather than taking off under their own power.

But compared with its biological inspiration, DASH had certain limitations as to where it could scamper. Remaining stable while going over obstacles is fairly tricky for small robots, so the researchers affixed DASH with lateral and tail wings.

The fossil evidence we do have suggests that the precursors to early birds had long feathers on all four limbs, and a long tail similarly endowed with a lot of feathers, which would mechanically be more beneficial for tree-dwelling gliders than for runners on the ground, said Dudley.

Dudley said that the winged version of DASH is not a perfect model for proto-birds as it has six legs instead of two, and its wings use a sheet of plastic rather than feathers, thus could not provide a confirmatory test on the evolution of flight.

What the experiments did do was to demonstrate the feasibility of using robot models to test hypotheses of flight origins, he said. It's the proof of concept that we can actually learn something useful about biological performance through systematic testing of a physical model.

He referenced previous computer models suggesting that ground-dwellers, given the right conditions, would need only to triple their running speed in order to build up enough thrust for takeoff.

With wings, we saw improvements in performance almost immediately, said study lead author Kevin Peterson.  Not only did the wings make the robot faster and better at steeper inclines, it could now keep itself upright when descending.

The wingless version of DASH could survive falls from eight stories tall, but it would sometimes land upside down, and where it landed was partly guided by luck.

The fact that DASH+Wings could maximally muster a doubling of its running speed suggests that wings do not provide enough of a boost to launch an animal from the ground. This finding is consistent with the theory that flight arose from animals that glided downwards from some height.

The researchers ran tests on four different configurations of the robotic roach, now called DASH+Wings. The test robots included one with a tail only and another that just had the wing's frames, to determine how the wings impacted locomotion.

The flapping wings improved the lift-drag ratio, helping DASH+Wings land on its feet instead of just plummeting uncontrolled. Once it hit the ground, the robot was able to continue on its way. Wind tunnel experiments showed that it is aerodynamically capable of gliding at an angle up to 24.7 degrees.

DASH+Wings joins a host of other running and flapping robots developed in UC Berkeley's Biomimetic Millisystems Laboratory, including a study on Octoroach, an eight-legged, hand-sized crawling robot that has a range of about 100 meters, and BOLT (Bipedal Ornithopter for Locomotion Transitioning), a two-legged, wing-enhanced running robot that weighs half an ounce and can take off in less than a yard.