A micro air vehicle (MAV), or micro aerial vehicle, is a class of miniature UAVs that has a size restriction and may be autonomous. Modern craft can be as small as 15 centimetres. Development is driven by commercial, research, government, and military purposes; with insect-sized aircraft reportedly expected in the future. The small craft allows remote observation of hazardous environments inaccessible to ground vehicles. MAVs have been built for hobby purposes, such as aerial robotics contests and aerial photography.
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.