By John McHale
ATLANTA - Scientists at the Georgia Institute of Technology are designing a robin-sized autonomous aircraft that flies like a mosquito to maneuver through battlefields to spy on the enemy, detect toxic chemicals, or sting an enemy with a poison needle.
The initial applications for the microflyers will be military, yet civilians, such as police, firefighters, scientists, and farmers will be the ultimate users, says Samuel Blankenship, coordinator of the Georgia Tech Focused Research Program for Microflyers in Atlanta.
In the military role, these six-inch machines will be able to retrieve visual, chemical, and biological target information, say Georgia Tech researchers.
However, due to the size of the devices and the strength of wind and rain, it is nearly impossible to use microflyers outside, says Robert Michelson, a Georgia Tech principal research engineer. The best applications for them, he says, will be indoors.
Major problems for the designers to over come are weight, power, control, and aerodynamics. The entire device must weigh less than four ounces.
Since a drop of gasoline has more energy potential than current batteries of the same size, early models will probably use fossil fuels, researchers say. As an added plus, a simulated muscle could generate electricity for sensors.
Michelson developed a reciprocating chemical muscle that uses a monopropellant fuel to generate an up-and-down motion like beating wings. Fixed-wing aircraft of this size are not practical, he says.
The prototype, which has a 10-inch wingspan, flaps its wings as the fuel is injected into the body. Gas generated as a byproduct of the simulated muscle can turn the aircraft by changing the lift on one wing or the other.
The next step is to shrink the simulated muscle down to bug size, Michelson says, adding that he believes he could make a system in which the microflyer would consume itself as it flies to generate energy.
Prototype chemical and biological sensors are small chips of glass with optical wave guides that can trap and manipulate light, says Robert Schwerzel, a principal research scientist at Georgia Tech.
"With this technology, you can design each sensing/reference pair to respond to a particular type of analyte," Schwerzel explains. "We can put up to two dozen channels on a sensor chip to determine what the microflyer is flying through."
The visual sensors may use active-pixel arrays already used in real-time image processing, says Joy Laskar, assistant professor of electrical and computer engineering.
For the tiny visual chips` design Laskar`s team is using a lift-off technique, which removes the existing integrated circuit from the bottom of a wafer then bonds it onto a new host substrate. This enables the optical circuits to take advantage of the new substrate`s properties, Laskar says.
Additionally, Laskar and his colleagues are examining how to communicate with the microflyers, how to download information from the microflyer, and how to safeguard information and communications.
Microflyers will use RF frequencies higher than standard cellular telephone, which allows for a smaller antenna. A geographic information system and a global positioning system have been proposed to give the machine autonomy, but do not work indoors. Recent advances in micro electro-mechanical systems and microelectronics technology have helped in the design, Michelson says.
Projected requirements for microflyers call for a size smaller than six inches at largest point; four-ounce weight; 50 mile-per-hour speed; 6.2 mile range; and price less than $1,000 per unit.
A series of workshops and meetings at the Defense Advanced Research Projects Agency (DARPA) in 1995 involved early researchers in this field in the planning process, and led to the establishment of the DARPA micro Air Vehicle (microAV) Program.
Georgia Tech specialists, who have supplied initial funding to launch the project, have partnered with other agencies, including the Air Force Institute of Technology and the Institute of Defense Analyses.
Scientists from Georgia Tech are developing a bird-like unmanned aircraft for a variety of battlefield surveillance tasks.
