WRIGHT-PATTERSON AIR FORCE BASE, Ohio — To conduct surveillance missions while on patrol in Afghanistan, soldiers and marines hand-launch toy model-sized airplanes called the Raven.
If Air Force Research Laboratory scientists are successful in the coming five years, troops one day may send up robots that actually look and fly like real birds.
In a new $1.5 million micro air vehicle indoor flight test facility, researchers are developing a small avian robot capable of operating semi-autonomously for a week with onboard sensors to detect weapons of mass destruction.
“What we’re doing here in the lab is we’re exploring the science and engineering and the design challenges to make this a reality,” said Leslie Perkins, who leads the lab’s micro air vehicles activity.
Humans have explored flight for more than 100 years and have become successful with aviation technologies on a macro level. But the translation of that knowledge to small-scale systems — especially aircraft that will fly using flapping wings — is still in its infancy.
“We’re really in the early 1900s with these micro-vehicles,” Perkins said. “We know a lot, but we don’t know how all of the areas will work, and how all the areas will work together.”
To begin understanding the challenges of designing and ultimately operating bird-sized or insect-sized technologies, researchers are studying how remote-controlled toy aircraft fly in different environments. They are placing prototype sensors, processors and materials onto RC toy helicopters and flying them autonomously around the indoor test range. The facility is one of the largest in the country and so far the only place where scientists can flight test such vehicles in simulated terrain.
During a recent demonstration, researchers attached white round tracking sensors onto an RC helicopter and truck. “We put these markers on vehicles to track the orientation and position of the vehicle with 1 mm accuracy,” said Gregory Parker, the team lead for the micro air vehicles lab.
The instrumentation is the same as the VICON motion capture system widely used in the entertainment industry. When attached to special suits worn by actors or athletes, the sensors translate movements into electronic signals that are captured by computers for animation. In the same way, the RC vehicles’ motions are fed into the lab’s computers for analysis.
On several large screens next door in the control room, live video feeds showed the helicopter first hovering, then flying in a pattern and finally following the truck driving around in the testing lab.
“We can calculate velocities, accelerations, and actually have the computer off board the vehicle control it,” Parker said. “Right now, we’re doing component testing with different pieces of technology. In the next few years, there will be more and more work that’s fused.”
Creating micro air vehicles requires more than a simple scaling down of parts. As aircraft shrink down to dragonfly-sized systems, they have to contend with air behavior that is not well understood.
“The air acts like it’s stickier, so there’s more drag and less lift,” explained Parker. Scientists in the unstable aerodynamics lab next door are engaged in a number of experiments to understand the physics behind flying small-scale aircraft at slow speeds.
In the bench test lab, researchers are experimenting with flapping wings to come up with new techniques for measuring pressure flow.
“We’re putting a lot of emphasis on flapping wings because it’s not well understood,” said Parker. “How do you provide thrust, lift and control by moving the wings only?” Scientists have a good understanding of fixed-wing and rotary-wing technologies and how to maintain flight by employing wings for lift, propellers for thrust and special surfaces for control. But Mother Nature somehow combines all those aspects into a set of flapping wings.
Another group is investigating how birds are able to perch on a wire. Its task is to apply any discoveries to enable a bird-sized vehicle with a two-foot wingspan to alight on ledges, branches, or the ground, and take off again.
Lab officials expect to produce prototypes representative of the bird-like vehicle by 2015. Scientists plan to apply the robotic avian technology and science toward AFRL’s ultimate 2030 goal of demonstrating a biomimetic insect-sized UAV capable of autonomous flight and sensing, tracking and targeting weapons of mass destruction.
“We’re really embracing the new technologies and the new challenges that micro air vehicles afford. We’re taking flight to the next level,” said Perkins.