Volume 12, Number 3, 2004
As the nation celebrates the 100th anniversary of human flight, an internationally recognized robotics expert in the College of Engineering has turned his attention to the skies.
Sunil K. Agrawal, professor of mechanical engineering, is working on the design and construction of small robotic devices that mimic the flight of birds and insects, in particular the hummingbird and the hawkmoth.
Agrawal says that, once fully developed, the devices will be able to carry miniature cameras and fly in flock-like formations to send surveillance data back to a central computer for processing. Such detailed information would be of value in industrial and military applications, he says, and also could be used in police and rescue operations.
While the need for such devices in surveillance and telemetry has existed for some time, Agrawal says the technology to enable such miniaturization is relatively new and still evolving.
"We are quite enthusiastic about being able to build these machines," he says, adding that his research team focuses on the design, fabrication and control of a variety of devices in addition to the birds.
Early versions of the robotic birds were made of balsa wood and powered by rubber band engines that made the wings flap, and the first successful flight was outside UD's Spencer Laboratory. A later design, with wings powered by battery, took flight on The Green, where researchers noticed an unexpected reaction.
"When it flew, birds from nearby came and circled around it," Agrawal says. That particular robotic bird spent two minutes in flight, but it lacked a means for remote control.
Current designs have replaced the balsa components with carbon fiber composites and use Mylar instead of paper for the wings, dropping the total weight from 50 to 15 grams and strengthening the frame to withstand crashes.
Agrawal says the research team now is working to optimize the design so that the mass and power required can be kept to a minimum. He says he hopes to further miniaturize the birds to the point that they are small enough to fit in the palm of a hand, while at the same time working to integrate controls to guide their flight.
When it comes time to control a group of birds in flight, Agrawal will turn to technologies he previously has developed to make land-bound robots work in unison.
"We want to demonstrate that the flapping wing machines can be built and optimized, and eventually, we would like to expand from a single flying machine to a group of cooperative flying machines," he says. "This will be in the future from where we are now, but it is where I think we would like to go."
For now, Agrawal says he simply wants to build a better bird. The research team is studying individual wing motions and observing birds and insects to better understand how they get lift. The hummingbird is a valuable model, according to Agrawal, because it can hover, and the ability to do that is key to effective surveillance.
"Making things mimic nature is much more difficult than it might seem," he says. "It is scientifically fascinating but also extremely challenging."
Agrawal says the research team plans to take its new designs to a wind tunnel, where the birds will be put in various flying attitudes to gather data on force and torque. That information will be used to predict how to improve and control the movement of the birds, and future designs will then be refined using computer models.
The idea for robotic birds came to him two years ago, Agrawal says, and he found support from U.S. Air Force officials at Eglin Air Force Base in Valparaiso, Fla. The military uses were readily apparent because if the robotic birds can provide a stable platform for cameras, they can create detailed maps of nearly any environment.
Industrial uses also are possible, with the birds compiling important information on large factory floors.
Further, there are police and rescue applications, with SWAT teams able to gather valuable data and rescue teams able to send the birds in to map the interiors of collapsed buildings.
Agrawal's laboratory receives funding from the National Science Foundation, the U.S. Air Force, the National Institute of Standards and Technology and the National Institutes of Health.
The Alexander von Humboldt Foundation recently honored Agrawal as one of 10 researchers worldwide to receive a 2001-03 Friedrich Wilhelm Bessel Research Award. He was presented the award at a ceremony last summer in Germany.
--Neil Thomas, AS '76