Unmanned Aerial Vehicle

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ABSTRACT:

The UAV is an acronym for Unmanned Aerial Vehicle, which is an aircraft with no pilot on board. UAVs can be remote controlled aircraft (e.g. flown by a pilot at a ground control station) or can fly autonomously based on pre-programmed flight plans or more complex dynamic automation systems. UAVs are currently used for a number of missions, including reconnaissance and attack roles. For the purposes of this article, and to distinguish UAVs from missiles, a UAV is defined as being capable of controlled, sustained level flight and powered by a jet or reciprocating engine. In addition, a cruise missile can be considered to be a UAV, but is treated separately on the basis that the vehicle is the weapon. The acronym UAV has been expanded in some cases to UAVS (Unmanned Aircraft Vehicle System). The FAA has adopted the acronym UAS (Unmanned Aircraft System) to reflect the fact that these complex systems include ground stations and other elements besides the actual air vehicles.
They have been used in a reconnaissance and intelligence-gathering role since the 1950s, and more challenging roles are envisioned, including combat missions. Since 1964 the Defense Department has developed 11 different UAVs, though due to acquisition and development problems only 3 entered production. The US Navy has studyied the feasibility of operating VTOL UAVs since the early 1960s, the QH-50 Gyrodyne torpedo-delivery drone being an early example. However, high cost and technological immaturity have precluded acquiring and fielding operational VTOL UAV systems.
By the early 1990s DOD sought UAVs to satisfy surveillance requirements in Close Range, Short Range or Endurance categories. Close Range was defined to be within 50 kilometers, Short Range was defined as within 200 kilometers and Endurance as anything beyond. By the late 1990s, the Close and Short Range categories were combined, and a separate Shipboard category emerged. The current classes of these vehicles are the Tactical UAV and the Endurance category.
Officially, the term 'Unmanned Aerial Vehicle' was changed to 'Unmanned Aircraft System' to reflect the fact that these complex systems include ground stations and other elements besides the actual air vehicles. The term UAS, however, is not widely used as the term UAV has become part of the modern lexicon.



History:
The earliest UAV was A. M. Low's "Aerial Target" of 1916. A number of remote-controlled airplane advances followed, including the Hewitt-Sperry Automatic Airplane, during and after World War I, including the first scale RPV (Remote Piloted Vehicle), developed by the film star and model airplane enthusiast Reginald Denny in 1935. More were made in the technology rush during the Second World War; these were used both to train antiaircraft gunners and to fly attack missions. Jet engines were applied after WW2, in such types as the Teledyne Ryan Firebee I of 1951, while companies like Beechcraft also got in the game with their Model 1001 for the United States Navy in 1955. Nevertheless, they were little more than remote-controlled airplanes until the Vietnam Era.
During the Yom Kippur War, Syrian missile batteries in Lebanon caused heavy damages to Israeli fighter jets. As a result, Israel developed the first modern UAV. The images provided by these UAVs helped Israel to completely neutralize the Syrian air defenses at the start of the 1982 Lebanon War, resulting in no pilots downed.
With the maturing and miniaturization of applicable technologies as seen in the 1980s and 1990s, interest in UAVs grew within the higher echelons of the US military. UAVs were seen to offer the possibility of cheaper, more capable fighting machines that could be used without risk to aircrews. Initial generations were primarily surveillance aircraft, but some were armed (such as the MQ-1 Predator, which utilized AGM-114 Hellfire air-to-ground missiles). An armed UAV is known as an unmanned combat air vehicle (UCAV).
As a tool for search and rescue, UAVs can help find humans lost in the wilderness, trapped in collapsed buildings, or adrift at sea.
What Is a UAV?
The term UAV is an abbreviation of Unmanned Aerial vehicle, meaning aerial vehicles which operate without a human pilot. UAVs are commonly used in both the military and police forces in situations where the risk of sending a human piloted aircraft is unacceptable, or the situation makes using a manned aircraft impractical.
One of the predecessors of today’s fully autonomous UAVs were the “aerial torpedoes”, designed and built during World War One. These were primitive UAVs, relying on mechanical gyroscopes to maintain straight and level flight, and flying until they ran out of fuel. They would then fall from the sky and deliver and explosive payload.
More advanced UAVs used radio technology for guidance, allowing them to fly missions and return. They were constantly controlled by a human pilot, and were not capable of flying themselves. This made them much like todays RC model airplanes which many people fly as a hobby. It is interesting to note that the government considers all aircraft UAVs, if they are unmanned and used by a government or business.
After the invention of the integrated circuit, engineers were able to build sophisticated UAVs, using electronic autopilots. It was at this stage of development that UAVs became widely used in military applications. UAVs could be deployed, fly themselves to a target location, and either attack the location with weapons, or survey it with cameras and other sensor equipment.
Modern UAVs are controlled with both autopilots, and human controllers in ground stations. This allows them to fly long, uneventfully flights under their own control, and fly under the command of a human pilot during complicated phases of the mission.

What Are UAVs Used For?
Since their creation, UAVs have found many uses in police, military, and in some cases, civil applications. Currently, UAVs are most often used for the following tasks:

Aerial Reconnaissance – UAVs are often used to get aerial video of a remote location, especially where there would be unacceptable risk to the pilot of a manned aircraft. UAVs can be equipped with high resolution still, video, and even infrared cameras. The information obtained by the UAV can be streamed back to the control center in real time.
Scientific Research – In many cases, scientific research necessitates obtaining data from hazardous, or remote locations. A good example is hurricane research, which often involves sending a large manned aircraft into the center of the storm to obtain meteorological data. A UAV can be used to obtain this data, with no risk to a human pilot.
Logistics and Transportation – UAVs can be used to carry and deliver a variety of payloads. Helicopter type UAVs are well suited to this purpose, because payloads can be suspended from the bottom of the airframe, with little aerodynamic penalty.


UAV Types:
• Target and decoy - providing ground and aerial gunnery a target that simulates an enemy aircraft or missile
• Reconnaissance - providing battlefield intelligence
• Combat - providing attack capability for high-risk missions (see Unmanned Combat Air Vehicle)
• Research and development - used to further develop UAV technologies to be integrated into field deployed UAV aircraft
• Civil and Commercial UAVs - UAVs specifically designed for civil and commercial applications.

Degree of autonomy:

Early UAVs used during the Vietnam War after launch captured video that was recorded to film or tape on the aircraft. These aircraft often were launched and flew either in a straight line or in preset circles collecting video until they ran out of fuel and landed. After landing, the film was recovered for analysis. Because of the simple nature of these aircraft, they were often called drones. As new radio control systems became available, UAVs were often remote controlled and the term "remotely piloted vehicle" came into vogue. Today's UAVs often combine remote control and computerized automation. More sophisticated versions may have built-in control and/or guidance systems to perform low-level human pilot duties such as speed and flight-path stabilization, and simple scripted navigation functions such as waypoint following. In news and other discussions, often the term "drone" is still mistakenly used to refer to these more sophisticated aircraft.
From this perspective, most early UAVs are not autonomous at all. In fact, the field of air-vehicle autonomy is a recently emerging field, whose economics is largely driven by the military to develop battle-ready technology. Compared to the manufacturing of UAV flight hardware, the market for autonomy technology is fairly immature and undeveloped. Because of this, autonomy has been and may continue to be the bottleneck for future UAV developments, and the overall value and rate of expansion of the future UAV market could be largely driven by advances to be made in the field of autonomy.



Autonomy technology that is important to UAV development falls under the following categories:
Sensor fusion: Combining information from different sensors for use on board the vehicle
Communications: Handling communication and coordination between multiple agents in the presence of incomplete and imperfect information
Path planning: Determining an optimal path for vehicle to go while meeting certain objectives and mission constraints, such as obstacles or fuel requirements
Trajectory Generation (sometimes called Motion planning): Determining an optimal control maneuver to take to follow a given path or to go from one location to another
Trajectory Regulation: The specific control strategies required to constrain a vehicle within some tolerance to a trajectory
Task Allocation and Scheduling: Determining the optimal distribution of tasks amongst a group of agents, with time and equipment constraints
Cooperative Tactics: Formulating an optimal sequence and spatial distribution of activities between agents in order to maximize chance of success in any given mission scenario
Autonomy is commonly defined as the ability to make decisions without human intervention. To that end, the goal of autonomy is to teach machines to be "smart" and act more like humans. The keen observer may associate this with the development in the field of artificial intelligence made popular in the 1980s and 1990s such as expert systems, neural networks, machine learning, natural language processing, and vision. However, the mode of technological development in the field of autonomy has mostly followed a bottom-up approach, such as hierarchical control systems, and recent advances have been largely driven by the practitioners in the field of control science, not computer science. Similarly, autonomy has been and probably will continue to be considered an extension of the controls field.
To some extent, the ultimate goal in the development of autonomy technology is to replace the human pilot. It remains to be seen whether future developments of autonomy technology, the perception of the technology, and most importantly, the political climate surrounding the use of such technology, will limit the development and utility of autonomy for UAV applications. Also as a result of this, synthetic vision for piloting has not caught on in the UAV arena as it did with manned aircraft. NASA utilized synthetic vision for test pilots on the HiMAT program in the early 1980s (see photo), but the advent of more autonomous UAV autopilots, greatly reduced the need for this technology.

Interoperable UAV technologies became essential as systems proved their mettle in military operations, taking on tasks too challenging or dangerous for troops. NATO addressed the need for commonality through STANAG (Standardization Agreement) 4586. According to a NATO press release, the agreement began the ratification process in 1992. Its goal was to allow allied nations to easily share information obtained from unmanned aircraft through common ground control station technology. STANAG 4586 — aircraft that adhere to this protocol are equipped to translate information into standardized message formats; likewise, information received from other compliant aircraft can be transferred into vehicle-specific messaging formats for seamless interoperability. Amendments have since been made to the original agreement, based on expert feedback from the field and an industry panel known as the Custodian Support Team. Edition Two of STANAG 4586 is currently under review. There are many systems available today that are developed in accordance with STANAG 4586, including products by industry leaders such as AAI Corporation, CDL Systems, and Raytheon, all three of which are members of the Custodian Support Team for this protocol.
Endurance:
Because UAVs are not burdened with the physiological limitations of human pilots, they can be designed for maximized on-station times. The maximum flight duration of unmanned, aerial vehicles varies widely. Internal-combustion-engine aircraft endurance depends strongly on the percentage of fuel burned as a fraction of total weight (the Breguet endurance equation), and so is largely independent of aircraft size. Solar-electric UAVs hold potential for unlimited flight, a concept originally championed by the AstroFlight Sunrise in 1974 and the much later Aerovironment Helios Prototype, which was destroyed in a 2003 crash. One of the major problems with UAVs is no capability for inflight refueling. Currently the US Air Force is promoting research that should end in an inflight UAV refueling capability, which should be available by 2010.

One of the uses for a high endurance UAV would be to "stare" at the battlefield for a long period of time to produce a record of events that could then be played backwards to track where IEDs came from. Air Force Chief of Staff John P. Jumper started a program to create these persistent UAVs, but this was stopped once he was replaced.
The Defense Advanced Research Projects Agency (DARPA) is to sign a contract on building an UAV which should have an enormous endurance capability of about 5 years. The project is entitled "Vulture". The developers are certain neither on the design of the UAV nor on what fuel it should run to be able to stay in air without any maintenance for such a long period of time.

UAV functions:
UAVs perform a wide variety of functions. The majority of these functions are some form of remote sensing; this is central to the reconnaissance role most UAVs fulfill. Less common UAV functions include interaction and transport.
Remote sensing:
UAV remote sensing functions include electromagnetic spectrum sensors, biological sensors, and chemical sensors. A UAV's electromagnetic sensors typically include visual spectrum, infrared, or near infrared cameras as well as radar systems. Other electromagnetic wave detectors such as microwave and ultraviolet spectrum sensors may also be used, but are uncommon. Biological sensors are sensors capable of detecting the airborne presence of various microorganisms and other biological factors. Chemical sensors use laser spectroscopy to analyze the concentrations of each element in the air.
Transport:
UAVs can transport goods using various means based on the configuration of the UAV itself. Most payloads are stored in an internal payload bay somewhere in the airframe. For many helicopter configurations, external payloads can be tethered to the bottom of the airframe. With fixed wing UAVs, payloads can also be attached to the airframe, but aerodynamics of the aircraft with the payload must be assessed. For such situations, payloads are often enclosed in aerodynamic pods for transport.
Scientific research:
Unmanned aircraft are uniquely capable of penetrating areas which may be too dangerous for piloted craft. The National Oceanic and Atmospheric Administration (NOAA) began utilizing the Aerosonde unmanned aircraft system in 2006 as a hurricane hunter. AAI Corporation subsidiary Aerosonde Pty Ltd. of Victoria (Australia), designs and manufactures the 35-pound system, which can fly into a hurricane and communicate near-real-time data directly to the National Hurricane Center in Florida. Beyond the standard barometric pressure and temperature data typically culled from manned hurricane hunters, the Aerosonde system provides measurements far closer to the water’s surface than previously captured. Further applications for unmanned aircraft can be explored once solutions have been developed for their accommodation within national airspace, an issue currently under discussion by the Federal Aviation Administration. UAVSI, the UK manufacturer also produce a variant of their Vigilant light UAS (20 kg) designed specifically for scientific research in severe climates such as the antarctic.

Armed attacks:
MQ-1 Predator UAVs armed with Hellfire missiles are now used as platforms for hitting ground targets in sensitive areas. Armed Predators were first used in late 2001 from bases in Pakistan and Uzbekistan, mostly for assassinations inside Afghanistan. Since then, there were several reported cases of such assassinations taking place in Pakistan, this time from Afghan-based Predators. The advantage of using an unmanned vehicle, rather than a manned aircraft in such cases, is to avoid a diplomatic embarrassment should the aircraft be shot down and the pilots captured, since the bombings took place in countries deemed friendly and without the official permission of those countries.

A Predator, based in a neighboring Arab country, was used to kill suspected al-Qaeda terrorists in Yemen on November 3, 2002. This marked the first use of an armed Predator as an attack aircraft outside of a theater of war such as Afghanistan.
Questions have been raised about the accuracy of the targeting of UAVs. In March 2009, The Guardian reported that Israeli UAVs armed with missiles killed 48 Palestinian civilians in the Gaza Strip, including two small children in a field and a group of women and girls in an otherwise empty street. In June, Human Rights Watch investigated six UAV attacks which resulted in civilian casualties, and found that Israeli forces either failed to take all feasible precautions to verify that the targets were combatants, or failed to distinguish between combatants and civilians. In July 2009, Brookings Institution released a report stating that in the United States-led drone attacks in Pakistan, ten civilians died for every militant killed. S. Azmat Hassan, a former ambassador of Pakistan, said in July 2009 that American UAV attacks were turning Pakistani opinion against the United States, and that 35 or 40 such attacks only killed 8 or 9 top al-Qaeda operatives. However, the attacks are believed to have achieved the desired psychological effect in that Pakistani civilians are becoming loathe to support al-Qaeda operatives, believing that doing so will result in further attacks by the UAVs.[citation needed]

Search and rescue:
UAVs will likely play an increased role in search and rescue in the United States. This was demonstrated by the successful use of UAVs during the 2008 hurricanes that struck Louisiana and Texas.
For example, Predators, operating between 18,000–29,000 feet above sea level, performed search and rescue and damage assessment. Payloads carried were an optical sensor, (which is a daytime and infra red camera), and a synthetic aperture radar. The Predator's SAR is a sophisticated all-weather sensor capable of providing photographic-like images through clouds, rain or fog, and in daytime or nighttime conditions; all in real-time. A concept of coherent change detection in SAR images allows for exceptional search and rescue ability: photos taken before and after the storm hits are compared and a computer highlights areas of damage.


Indian UAV’S:
 The DRDO Rustom UAV at the Display.
 DRDO Nishant
 DRDO Rustom
 Lakshya PTA
 HAL/DRDO Gagan Tactical UAV [20]
 Ulka
 Fluffy uav
 Pawan uav
 Kapothaka
 Sparrow uav

Conclusion:
UAVs represent an area of rapid development in both military and civilian applications. UAVs unique capability of flying dangerous, long, or precision missions give it a unique advantage over conventional aircraft.
UAV and UCAV represent a significant step in the right direction. They will augment manned flight, not replace it. Only extreme futurists predict the end of humans in cockpits. Placing total reliance on anything creates a single point of failure that could be easily exploited. Therefore, we must embrace the advantages of UAV and guided weapons. They are cheaper to mass-produce, eliminate some risk to humans, are generally more accurate, and do not mind flying into a "no-win" situation. Relegating the UAV to only ISR missions would be no less provincial and narrow minded than limiting the airplane to scouting and patrolling.