Tiny Rescue Robot Earns its Wings
Cockroaches were the inspiration for DASH+Wings, a flying robot that could help shed light on the evolution of bird flight.
CREDIT: K. Peterson, P. Birkmeyer, R. Dudley, R. S. Fearing
A robot resembling a winged cockroach may lead to better flying robots and could also shed light on the evolution of flight in birds and could, researchers say.
The 4-inch-long (10 centimeters) robot in question is named DASH, short for "Dynamic Autonomous Sprawled Hexapod." The speedy, lightweight mechanical bug is made of inexpensive off-the-shelf components; its six legs are driven by a battery-powered motor.
DASH started out without wings. Its designers suggested deploying DASH inside areas too cramped or dangerous for humans, such as collapsed buildings. Compared to the cockroach, however, DASH had certain limitations on where it could scamper. For instance, small robots find it fairly tricky to remain upright and stable while clambering over obstacles.
To help DASH tackle rough terrain, its designers added motorized flapping wings onto it from a store-bought toy. The resulting droid was named "DASH+Wings."
"Our overall goal is to give our robots the same all-terrain capabilities that other animals have," said researcher Ron Fearing, head of the Biomimetic Millisystems Lab at the University of California, 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."
The researchers found DASH+Wings had significantly improved mobility. For instance, it ran almost twice as fast as DASH, going from 2.2 feet (0.68 meters) per second with legs alone to 4.2 feet (1.29 meters) per second. The robot was also better at steeper inclines, going from an incline angle of 5.6 degrees to 16.9 degrees.
"With wings, we saw improvements in performance almost immediately," said Berkeley researcher Kevin Peterson. "Getting a doubling of speed from adding the wings was an exciting result for us."
The robot also was able to stay upright when descending, land on its feet and continue on its way. In comparison, "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," Peterson said.
The researchers think that future versions of the winged DASH bot could help search for survivors in collapsed buildings. "In confined spaces, crawling is a better way to navigate compared to flying however, there may be obstacles or passages that a crawling robot cannot navigate, and in these situations flight is necessary," Peterson told InnovationNewsDaily. "Applications also exist in the exploration of other hazardous areas and in reconnaissance."
Tree-dwellers versus ground-runners
Wind tunnel experiments showed that DASH+Wings was capable of gliding at an angle up to 24.7 degrees a finding that could help shed light on how flight evolved in birds, researchers said.
Scientists are currently split over whether the ancestors of today's flying birds were tree-dwellers or ground-runners. One idea is that ancient bird-like reptiles glided from tree to tree, a practice that evolved into flight. Another hypothesis is that they flapped their wings to help them run on the ground, which eventually helped them fly.
Fossil evidence of the origin of bird flight is limited, but robot models such as DASH+Wings could help resolve the debate, said researcher Robert Dudley, an animal flight expert at Berkeley.
Past computer models suggested that ground-dwellers would have had to triple their running speed to build up enough thrust for takeoff. Since DASH+Wings can only double its running speed not enough to launch it from the ground this suggests the ancestors of birds might have been gliding tree-dwellers instead.
"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," Dudley explained.
The winged version of DASH is not a perfect model for proto-birds, Dudley cautioned. For example, it has six legs instead of two, and its wings use a sheet of plastic rather than feathers. As such, it cannot provide a slam-dunk answer to the question of how bird flight evolved.
"What the experiments did do was to demonstrate the feasibility of using robot models to test hypotheses of flight origins," Dudley said. "It's the proof of concept that we can actually learn something useful about biological performance through systematic testing of a physical model."
Now the researchers are testing a winged, bipedal robot called BOLT ("Bipedal Ornithopter for Locomotion Transitioning") that more closely resembles the size and aerodynamics of precursors to flying birds. The aim is to better determine the most likely pathways evolution followed toward bird flight.
Understanding the origins of bird flight could in turn lead to improved flying robots, Peterson said.
"When studying the mechanics of animal locomotion, it is important to differentiate the features that animals have evolved for locomotion versus the features they have evolved for other purposes," he explained. "For example, several birds have large colorful tails which have evolved to attract a mate despite being aerodynamically inefficient. Understanding the initial evolution of flight in birds may give us better understanding of which morphological and kinematic features are the most important for a flying robot, leading to an overall improved design."
The researchers detailed their findings regarding DASH+Wings online Oct. 18 in the journal Bioinspiration and Biomimetics.