Small Robotic Devices Fly Like Birds

Sunil K. Agrawal, UD 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 said 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 and also could be used in rescue operations to map the interiors of collapsed buildings.

While the need for such devices in surveillance and telemetry has existed for some time, Agrawal said the technology to enable such miniaturization is relatively new and still evolving.

"We are quite enthusiastic about being able to build these machines," according to Agrawal, whose research team is focused 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 Spencer Laboratory.

A subsequent design, with wings powered by battery, took flight on the University's Green and they noticed an unexpected reaction. "When it flew, birds from nearby came and circled around it," Agrawal said. That robotic bird spent two minutes in flight but lacked a means for remote control.

Current designs have replaced the balsa components with carbon fiber composites and paper wings with Mylar, dropping the total weight from 50 to 15 grams and strengthening the frame to withstand crashes.

Agrawal said the research team is now working to optimize the design so that the mass and power required can be kept to a minimum. He said 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 flight.

When it comes time to control a group of birds in flight, Agrawal will turn to technologies he 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," Agrawal said. "This will be in the future from where we are now, but it is where I think we would like to go."

At the moment, Agrawal says he simply wants to build a better bird. The research team is studying individual wing motions, and looking at birds and insects to better understand how they get lift. The hummingbird is a valuable model, he said, 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," Agrawal said. "It is scientifically fascinating but also extremely challenging."

Agrawal said the research team plans to take 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.

Agrawal said the idea for robotic birds came to him two years ago, 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 honored Agrawal as one of 10 researchers worldwide to receive a 2001-03 Friedrich Wilhelm Bessel Research Award at a ceremony held in Berlin, Germany, June 27.