Naval Air Weapons Station China Lake, California - The RQ-16 T-Hawk, a Micro Air Vehicle (MAV), flies over a simulated combat area during an operational test flight. The MAV is in the operational test phase with military Explosive Ordnance Disposal (EOD) teams to evaluate its short-range scouting capabilities.
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,[2] such as aerial robotics contests and aerial photography.
Practical limitations.
Although there are currently no true MAVs (i.e., truly micro scaled flyers) in existence, DARPA has attempted a program to develop even smaller Nano Air Vehicles (NAVs) with a wingspan of 7.5 centimeters. However, no NAVs meeting DARPA's original program specification were forthcoming until 2009 when AeroVironment demonstrated a controlled hovering of DARPA's flapping-wing NAV.
Beyond the difficulties in developing MAVs, few designs adequately address control issues. The MAVs' small size makes teleoperation impractical because a ground station pilot cannot see it beyond 100 meters. An onboard camera allowing the ground pilot to stabilize and navigate the craft was first demonstrated in the Aerovironment Black Widow, but truly micro air vehicles cannot carry onboard transmitters powerful enough to allow for teleoperation. For this reason, some researchers have focused on fully autonomous MAV flight. One such device, which has been designed from its inception as a fully autonomous MAV, is the biologically-inspired Entomopter originally developed at the Georgia Institute of Technology under a DARPA contract by Robert C. Michelson.
Given that MAVs can be controlled by autonomous means, significant test and evaluation issues continue to exist.
Bio-inspiration
A new trend in the MAV community is to take inspiration from flying insects or birds to achieve unprecedented flight capabilities. Biological systems are not only interesting to MAV engineers for their use of unsteady aerodynamics with flapping wings; they are increasingly inspiring engineers for other aspects such as distributed sensing and acting, sensor fusion and information processing. Recent research within the USAF has focused on development of bird like perching mechanism. A ground mobility and perching mechanism inspired from bird claws was recently developed by Bhargav Gajjar of Vishwa Robotics and MIT sponsored by US Air Force Research Laboratory
Various symposia bringing together biologists and aerial roboticists have been held with increasing frequency since 2000 and some books have recently been published on this topic. Bio-inspiration has been also used in design of methods for stabilization and control of systems of multiple MAVs. Researchers took inspiration from observed behaviors of schools of fish and flocks of birds to control artificial swarms of MAVs and from rules observed in groups of migratory birds to stabilize compact MAV formations.
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.
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. The group has achieved controlled hovering flight in 2013 as well as landings on and takeoffs from different overhangs in 2016 (both inside a motion tracking environment).
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.
The term micro air vehicle (MAV) refers to a new type of remotely controlled aircraft (UAV) that is significantly smaller than similar aircraft's, obtainable by using state of the art technology. The target dimension for MAVs today is approximately 15 centimeters (six inches) and development of insect-sized aircrafts is reportedly expected in the near future. Potential military use is one of the driving factors, although MAVs are also being used commercially and in scientific, police, and mapping applications.
While AVID's expertise spans all differing types of MAVs such as fixed wing models, insect-like (flapping wing) models, and rotary wing models, AVID has a particular design and deployment success in rotary (or ducted fan) models.
About AVID EDF-8
AVID EDF-8 is a micro-aerial-robot platform designed to navigate indoors and in tight spaces. In addition to providing significant lift, the duct provides safety by shrouding the high speed fan. This vehicle can carry up to a 1 poun d payload to meet the customer’s requirement. It is a soccer ball-sized ducted-fan UAV capable of vertical takeoff and hovering flight. The vehicle is a UAV platform which has endless applications, especially for the dull, dangerous and dirty jobs such as performing ballast and fuel tank inspections, eliminating the need for people to enter the hazardous tank environment, while reducing time and costs. The ducted-fan architecture of AVID EDF-8 makes it compact, easy to deploy, and more cost effective than other comparable platforms.
About T-Hawk
AVID, in subcontract with Honeywell, assisted in the design of the first-ever deployed VTOL (Vertical Take-Off and Landing) ducted-fan micro air vehicle (MAV) as part of an accelerated DARPA project. AVID provided unique design expertise, as well as comprehensive design and analysis tools. The company supplied aerodynamic performance analysis for the vehicle and designed many of the aerodynamic components including the fan, stators, and control vanes. In 2007, the MAV was successfully deployed to Iraq and Afghanistan to assist US troops by identifying Improvised Explosive Devices (IEDs) from the air. It has logged more than 10,000 flights in missions that included explosive ordnance disposal exercises in Iraq. In 2011, T-Hawk was deployed in Japan to assist in the assessment of the nuclear facilities damaged after the devastating earthquake and tsunami. T-Hawk’s hover and stare ability offered a safe way to monitor the disabled Fukushima Daiichi nuclear plant without putting personnel at risk. The MAV will also be used to help ground vehicles navigate their way around obstacles.
AVID was named Lead for the aerodynamic configuration development and air-framing of the US Army’s BCTM Class I increment II vehicle. This lineage of ducted fan vehicles shows an increasing knowledge and maturity of design that is evidenced by an expanded design space and use of optimization techniques to satisfy challenging constraints. In March 2011, the MAV made its first successful test flight.
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