Robobugs Prepare for Flight
There are at least two DARPA-funded MAV projects that have been inspired by the principles of insect flight. While Michael Dickinson is creating the micromechanical flying insect at Berkeley, Robert Michelson, a research engineer at the Georgia Institute of Technology, is working on the Entomopter. Let's take a closer look at both projects.
In July 2000, the United States Patent Office awarded a patent to Georgia Tech Research Corporation for Michelson's invention of the Entomopter, also called a multimodal electromechanical insect. The Entomopter is being designed for possible indoor operations, according to U.S. Patent Number 6,082,671. It will mimic the fight of an insect by flapping its wings to generate lift. In addition, researchers are studying ways for the Entomopter to navigate hallways and ventilation systems and crawl under doors.
Let's look at the basic parts of the Entomopter:
- Fuselage - Just like in larger aircraft, this is the hull of the machine and houses the power source and primary fuel tank. All other components of the Entomopter are attached to the fuselage.
- Wings - There are two wings, front and rear, which are pivotally coupled to the fuselage in an X configuration. These wings are made out of a thin film. Stiff but flexible veins are attached to the wings at the fuselage junction to give the wings the curve they need to generate lift on both the upstroke and the downstroke.
- Reciprocating Chemical Muscle (RCM) - A compact, noncombustive engine is attached to the wings to create a flapping motion.
- Sensors - There are sensors for looking forward, downward and sideways.
- Camera - The prototype lacks a mini-camera, but the final version could carry a camera or an olfactory sensor. This sensor would detect odors, and the Entomopter would track the odors to their point of origin.
- Surface steering mechanism - This aids in navigation when the Entomopter is used in ground missions.
- Legs/feet - Also called surface locomotors, these parts provide anti-roll inertia and auxiliary fuel storage.
The Entomopter is powered by a chemical reaction. A monopropellant is injected into the body, causing a chemical reaction that releases a gas. The gas pressure that builds up pushes a piston in the fuselage. This piston is connected to the pivotally coupled wings, causing them to flap rapidly. Some of the gas is exhausted through vents in the wing and can be used to change the lift on either wing so the vehicle can turn. Currently, the Entomopter has a 10-inch (25-cm) wingspan. "The next step is to shrink the RCM device down to bug size," said Michelson.
In a vehicle the size of a house fly, every part must perform multiple tasks. For example, a radio antenna attached to the back of the vehicle may also act as a stabilizer for navigation. The legs could store fuel for adjustment of the vehicle's weight and balance during flight.