26-06-2012, 01:13 PM
MICRO AIR VEHICLES
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ABSTRACT
A new trend in the MAV community is to take inspiration from flying insects or birds to achieve unprecedented flight capabilities.
The demand for small unmanned air vehicles, commonly termed micro air vehicles, is rapidly increasing. Micro Air Vehicles (MAVs) are small flying robotic systems. There are still numerous scientific challenges to be solved in order to fly Micro Air Vehicles Under all flight and weather conditions.
The development of MAVs requires knowledge from areas such as electronics, mechanics, miniaturized structures, propulsion and navigation systems, aerodynamics, flight controllers, actuators and sensors are just a few of the current research topics in the field of MAVs.
The subject is highly relevant as the Defence Services need systems appropriate to Military Operations in Urban Terrain (MOUT), Light-Combat Survivability and Force Protection (FP). Presently such support is being given by a larger class of UAVs, but MAVs definitely enjoy greater advantage.
The systems are also important for civilian applications such as disaster management, urban traffic monitoring, search and rescue operations. Mission success requires a combination of technical capability and tactical skill. This will push the limits of both the robotic systems and the human operators.
INTRODUCTION
The small speck in the sky approaches in virtual silence, unnoticed by the large gathering of soldiers below. In flight, its tiny size and considerable agility evade all but happenstance recognition. After hovering for a few short seconds, it perches on a fifth floor window sill, observing the flow of men and machines on the streets below. Several kilometres away, the platoon leader watches the action on his wrist monitor. He sees his target and sends the signal.
The tiny craft swoops down on the vehicle, alighting momentarily on the roof. It senses the trace of a suspected chemical agent and deploys a small tagging device, attaching it to the vehicle. Just seconds later it is back in the sky, vanishing down a narrow alley. Mission accomplished..
Sound like science fiction? This scenario may be closer than you think if success is achieved in the development of a new class of flight vehicles, the Micro Air Vehicles (MAVs), by the Defence Advanced Research Projects Agency (DARPA).
The high level of current interest in developing a class of very small flight vehicles is the result of the nearly simultaneous emergence of their technological feasibility and an array of compelling new military needs, especially in urban environments.
HISTORY
The first appearance of winged insects is shrouded in the past, but they probably took to the air almost 350 million years ago (Wotton, 1981; Ellington, 1991a). Wingspans of the early fossils ranged from 10 to 710 mm, and the form of the wings suggests a variety of adaptations in flight style.
The Protodonata, which were the ancestors of dragonflies, were among the early fliers; their wings were similar enough to modern forms to suggest comparable flight capabilities, although perhaps with less refinement. Through natural selection, the insects have been experimenting successfully with wings, kinematics, aerodynamics, control and sensory systems for hundreds of millions of years.
In the last decade, researchers have developed increasingly sophisticated unmanned air vehicles(UAV) for military applications. In the Persian Gulf War, for example, UAVs served in surveillance missions and as decoys to distract enemy air defences. Increased demands for intelligence are spawning the development of a smaller next-generation UAV called the micro air vehicle, or MAV.
Research on MAVs is primarily conducted by aerodynamic and robotic engineers who are attempting to improve the performance at small sizes of conventional fixed wings and rotary wings. However, there already exists a very successful design for intelligent MAVs with much better aerodynamic performance than conventional wings and rotors: the insects.
What is a Micro Air Vehicle?
The term, Micro Air Vehicle, may be somewhat misleading if interpreted too literally. We tend to think of flying model aircraft as "miniature", so the term "micro" now alludes to a class of significantly smaller vehicles. But MAVs are not small versions of larger aircraft. They are affordable, fully functional, militarily capable, small flight vehicles in a class of their own.
Why Micro Air Vehicles?
Why "micro"? Why not something larger?
Much more recently, interest has developed in small autonomous flying vehicles, largely motived by the need for aerial reconnaissance robots inside buildings and confined spaces, to identify and locate obstacles, mines, hostage location and terrorist guard teams. Additional tasks include stationary hovering, landing on rooftops to perform perch and stare operations, and use of chemical sensors to detect simulated chemical explosive mines. Industry, commerce and the military have all identified potential roles for such micro-air vehicles (MAVs).
The MAV program will focus on the technologies and components required to enable flight at these small scales, including flight control, propulsion and lightweight power, navigation and communications. These will build upon and exploit numerous DARPA technology development efforts, including advanced communications and information systems, high performance computer technology, Micro electro-mechanical Systems (MEMS), advanced sensors, lightweight, efficient high density power sources, and advanced electronic packaging technologies.
Technological feasibility follows from advances in several micro-technologies, including the rapid evolution of micro-electromechanical systems, also known as MEMS. These systems combine microelectronics components with comparably - sized mechanical elements of varying complexity to achieve useful and often unique functionality (e.g. integrated systems of sensors, actuators and processors).
In many cases, these devices are produced with established micro fabrication techniques, providing a high degree of optimism for eventual low-cost production potential. Other maturing micro systems such as tiny CCD-array cameras, equally small infra-red sensors and chip-sized hazardous substance detectors, have been catalytic in providing the motivation for like-sized delivery platforms