Micro Air Vehicle - Practical Implementations

Practical Implementations

In January 2010, the Tamkang University (TKU) in Taiwan realized autonomous control of the flight altitude of an 8-gram, 20-centimeter wide, flapping-wing MAV. The MEMS Lab in the TKU has been developing MAVs for several years, and since 2007 the Space and Flight Dynamics (SFD) Lab has joined the research team for the development of autonomous flight of MAVs. Instead of traditional sensors and computational devices, which are too heavy for most MAVs, the SFD combined a stereo-vision system with a ground station to control the flight altitude, making it the first flapping-wing MAV under 10 grams that realized autonomous flight.

In 2008, the TU Delft University in the Netherlands developed the smallest ornithopter fitted with a camera, the Delfly Micro, the third version of the Delfly project that started in 2005. This version measures 10 centimeters and weighs 3 grams, slightly larger (and noisier) than the dragonfly on which it was modeled. The importance of the camera lies in remote control when the Delfly is out of sight. However, this version has not yet been successfully tested outside, although it performs well indoors. Researcher David Lentink of Wageningen University, who participated in the development of previous models, DelFly I and DelFly II, says it will take at least half a century to mimic the capabilities of insects, with their low energy consumption and multitude of sensors—not only eyes, but gyroscopes, wind sensors, and much more. He says fly-size ornithopters should be possible, provided the tail is well designed. Rick Ruijsink of TU Delft cites battery weight as the biggest problem; the lithium-ion battery in the Delfly micro, at one gram, constitutes a third of the weight. Luckily, developments in this area are still going very fast, due to demand in various other commercial fields.

The next goals are an ornithopter weighing just one gram with a size of 3 centimeters, and a helicopter with the same specifications. There are no biological examples of such a design, but Lentink is looking into the flight of hummingbirds.

Ruijsink says the purpose of these craft is to understand insect flight and to provide practical uses, such as flying through cracks in concrete to search for earthquake victims or exploring radioactivity-contaminated buildings. Spy agencies and the military also see potential for such small vehicles as spies and scouts.

Robert Wood at Harvard University developed an even smaller ornithopter, at just 3 centimeters, but this craft is not autonomous in that it gets its power through a wire and is led along a rail.

In early 2008 the United States company Honeywell received FAA approval to operate its MAV, designated as gMAV in the national airspace on an experimental basis. The gMAV is the fourth MAV to receive such approval. The Honeywell gMAV uses ducted thrust for lift, allowing it to takeoff and land vertically and to hover. It is also capable of "high-speed" forward flight, according to the company, but no performance figures have been released. The company also states that the machine is light enough to be carried by a man. It was originally developed as part of a DARPA program, and its initial application is expected to be with the police department of Miami-Dade County, Florida.