Unmanned aerial vehicle

An unmanned aerial vehicle (UAV), commonly known as a drone, as an unmanned aircraft system (UAS), and also referred by several other names, is an aircraft without a human pilot aboard. The flight of UAVs may be controlled with various kinds of autonomy : either by a given degree of remote control from an operator, located on the ground or in another vehicle, or fully autonomously, by onboard computers.^[1]

Historically, UAVs were simple remotely piloted aircrafts, but autonomous control is increasingly being employed : UAV stands nowadays at the crossroads of aviation, electromagnetics, radiocommunication, computer science, avionics, automation, cybernetics, and even core fields of artificial intelligence such as computer vision, decision-making, machine learning and robotics.

UAVs are often preferred for missions that are too "dull, dirty or dangerous"^[2] for manned aircrafts. They have and are mostly found in military and special operation applications. Though, UAVs are increasingly finding uses in civil applications,^[3] such as policing and surveillance, aerial filming and hobbyist FPV racing.

Definition and terminology

There are several names in use for unmanned aerial vehicles, which generally refer to the same concept.

The term drone, more widely used by the public, was coined in reference to the resemblance of dumb-looking navigation and loud-and-regular motor sounds of old military unmanned aircrafts to the male bee. The term has seen strong opposition from aviation professionals and government regulators.^[4]

The term unmanned aircraft system (UAS) was adopted by the United States Department of Defense (DoD) and the United States Federal Aviation Administration in 2005 according to their Unmanned Aircraft System Roadmap 2005–2030.^[5] The International Civil Aviation Organization and the British Civil Aviation Authority have also adopted the term, while the European Union’s Single-European-Sky (SES) Air-Traffic-Management (ATM) Research (SESAR Joint Undertaking) roadmap for 2020 mentions it too.^[6] Unmanned aircraft system emphasizes the importance of other elements beyond an aircraft itself. It includes elements such as the ground control stations, data links and other related support equipment. A similar term is an unmanned-aircraft vehicle system (UAVS) remotely piloted aerial vehicle (RPAV), remotely piloted aircraft system (RPAS). Many similar terms are in use as well.

To distinguish UAVs from missiles, a UAV is defined as a "powered, aerial vehicle that does not carry a human operator, uses aerodynamic forces to provide vehicle lift, can fly autonomously or be piloted remotely, can be expendable or recoverable, and can carry a lethal or nonlethal payload".^[7] Therefore, cruise missiles are not considered UAVs because, like many other guided missiles, the vehicle itself is a weapon that is not reused, though it is also unmanned and in some cases remotely guided.

The definition of UAVs with respect to smaller remote controlled model aircraft is unclear. According to various definitions UAVs may or may not include model aircraft. Some jurisdictions base this definition on size or weight, however, the US Federal Aviation Administration defines any unmanned flying craft as a UAV regardless of size. In another approach, a radio-controlled aircraft becomes a drone with the addition of an autopilot AI, and ceases to be a drone when the AI is removed.^[8]

History

In 1849 Austria sent unmanned, bomb-filled balloons to attack Venice. Drone innovations started in the early 1900s and originally focussed on providing practice targets for training military personnel. UAV development continued during World War I, when the Dayton-Wright Airplane Company invented a pilotless aerial torpedo that would drop and explode at a preset time.^[9] The earliest attempt at a powered unmanned aerial vehicle was A. M. Low's "Aerial Target" of 1916.^[10] Nikola Tesla described a fleet of unmanned aerial combat vehicles in 1915.^[11] A number of remote-controlled-airplane advances followed during and after World War I, including the Hewitt-Sperry Automatic Airplane. The first scale remote piloted vehicle was developed by the film star and model-airplane enthusiast Reginald Denny in 1935.^[10] More emerged in the technology rush during World War II - used both to train antiaircraft gunners and to fly attack missions. Nazi Germany produced and used various UAV aircraft during the course of WWII. Jet engines entered service after World War II in such types as the Australian GAF Jindivik, and Teledyne Ryan Firebee I of 1951, while companies like Beechcraft also got in the game with their Model 1001 for the U.S. Navy in 1955.^[10] Nevertheless, they were little more than remote-controlled airplanes until the Vietnam War.

In 1959, the U.S. Air Force, concerned about losing pilots over hostile territory, began planning for the use of unmanned aircraft.^[12] Planning intensified after the Soviet Union shot down a U-2 in 1960. Within days, the highly classified UAV program started under the code name of "Red Wagon".^[13] The August 1964 clash in the Tonkin Gulf between naval units of the U.S. and North Vietnamese Navy initiated America's highly classified UAVs (Ryan Model 147, Ryan AQM-91 Firefly, Lockheed D-21) into their first combat missions of the Vietnam War.^[14] When the "Red Chinese"^[15] showed photographs of downed U.S. UAVs via Wide World Photos,^[16] the official U.S. response was "no comment".

The War of Attrition (1967-1970) saw the introduction of UAVs with reconnaissance cameras into combat in the Middle East.^[17] In the 1973 Yom Kippur War Israel used drones as decoys to spur opposing forces into wasting expensive anti-aircraft missiles.^[18]

In 1973 the U.S. military officially confirmed that they had been using UAVs in Southeast Asia (Vietnam).^[20] Over 5,000 U.S. airmen had been killed and over 1,000 more were missing or captured. The USAF 100th Strategic Reconnaissance Wing had flown about 3,435 UAV missions during the war^[21] at a cost of about 554 UAVs lost to all causes. In the words of USAF General George S. Brown, Commander, Air Force Systems Command, in 1972, "The only reason we need (UAVs) is that we don't want to needlessly expend the man in the cockpit."^[22] Later that same year, General John C. Meyer, Commander in Chief, Strategic Air Command, stated, "we let the drone do the high-risk flying ... the loss rate is high, but we are willing to risk more of them ... they save lives!"^[22]

During the 1973 Yom Kippur War, Soviet-supplied surface-to-air missile batteries in Egypt and Syria caused heavy damage to Israeli fighter jets. As a result, Israel developed the first UAV with real-time surveillance.^[23][24][25] The images and radar decoying 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.^[26] The first time UAVs were used as proof-of-concept of super-agility post-stall controlled flight in combat-flight simulations involved tailless, stealth technology-based, three-dimensional thrust vectoring flight control, jet-steering UAVs in Israel in 1987.^[27]

With the maturing and miniaturization of applicable technologies in the 1980s and 1990s, interest in UAVs grew within the higher echelons of the U.S. military. In the 1990s, the U.S. DoD gave a contract to AAI Corporation along with Israeli company Malat. The U.S. Navy bought the AAI Pioneer UAV which AAI and Malat developed jointly. Many of these Pioneer and newly developed U.S. UAVs saw service in the 1991 Gulf War. UAVs demonstrated the possibility of cheaper, more capable fighting machines, deployable without risk to aircrews. Initial generations primarily involved surveillance aircraft, but some carried armaments, such as the General Atomics MQ-1 Predator, which used AGM-114 Hellfire air-to-ground missiles.

CAPECON was a European Union project to develop UAV's,^[28] running from 1 May 2002 to 31 December 2005.^[29]

As of 2012, the USAF employed 7,494 UAVs - almost one in three USAF aircraft.^[30][31] The Central Intelligence Agency has also operated UAVs.^[32]

In 2013, John Horgan reported in National Geographic that at least 50 countries used UAVs, with China, Iran, Israel, and others designed and building their own varieties.^[33]

Classification

UAVs typically fall into one of six functional categories (although multi-role airframe platforms are becoming more prevalent):

• 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)
• Logistics – UAVs specifically designed for cargo and logistics operation
• Research and development – used to further develop UAV technologies to be integrated into field-deployed UAV aircraft
• Civil and commercial UAVs – specifically designed for civil and commercial applications

The U.S. Military UAV tier system is used by military planners to designate the various individual aircraft elements in an overall usage plan. The tiers do not refer to specific models of aircraft, but rather roles.

They can also be categorised in terms of range/altitude and the following has been advanced as relevant at such industry events as ParcAberporth Unmanned Systems forum:

• Hand-held 2,000 ft (600 m) altitude, about 2 km range
• Close 5,000 ft (1,500 m) altitude, up to 10 km range
• NATO type 10,000 ft (3,000 m) altitude, up to 50 km range
• Tactical 18,000 ft (5,500 m) altitude, about 160 km range
• MALE (medium altitude, long endurance) up to 30,000 ft (9,000 m) and range over 200 km
• HALE (high altitude, long endurance) over 30,000 ft (9,100 m) and indefinite range
• HYPERSONIC high-speed, supersonic (Mach 1–5) or hypersonic (Mach 5+) 50,000 ft (15,200 m) or suborbital altitude, range over 200 km
• ORBITAL low earth orbit (Mach 25+)
• CIS Lunar Earth-Moon transfer
• CACGS Computer Assisted Carrier Guidance System for UAVs

Some other classifications aiming at representing the complete scope of UAVs set :^[34][35]

• Hobbyist UAVs - wich can be further divided into
  • Ready-to-fly (RTF)/Commercial-off-the-shelf (COTS)
  • Bind-and-fly (BNF) - that require minimum knowledge to fly the platform
  • Almost-ready-to-fly (ARF)/Do-it-yourself(DIY) - that require significant knowledge to get in the air.
• Midsize military and commercial drones
• Large military-specific drones
• Stealth combat drones

Classifications according to aircraft size are quite simpler :

• Micro Air Vehicle (MAV) - the smallest UAVs that can weight less than 1g.
• Miniature UAV (also called SUAS) - approximately less than 25 kg.
• Other UAVs.

UAV systems

UAVs, as pieces of technology and engineering, are a field of systems science. The latter is emphasized by the term unmanned aircraft system (UAS), which directly hints at the multi-layer intricated systems : physical structure and powering sources, flight controls, telecommunication modules, autonomous planners, etc.

McRuer and Graham wrote a decade ago in A flight control century : triumphs of the system approach « The dangers of a new separation between theory and practice are, we believe, increasing. »^[36] This is purposely related to the new specificities of UAV control systems, and the concurrency of their development to older manned-aviation-systems masterpieces, such as spacecrafts, civil airliners or jet fighters ones.

Physical structure, hardware and software

Physical structure and hardware

The physical components of an UAV are roughly the same as on manned aircrafts, pilot set apart.

Body

Fuselage and wings for planes, tail rotor for helicopters, canopy, frame and arms for multirotors.

Evolution toward 3D printing applies to UAVs to cut in the aircraft weight.^[37]

Power supply and platform

Small UAVs rely mostly at present on lithium-polymer batteries (Li-Po), while larger vehicles often use fuel or even solar power.

Battery elimination circuitry (BEC) is used to centralize power distribution and often harbors a microcontroller unit (MCU). Costlier switching BECs diminish heating on the platform.

Computing

First large UAVs could carry high computational capabilities due to their extended available payload and did not urge engineers into miniaturization as they allowed complex-instruction-set chips ; whereas processing power of civil-and-medium-domestic UAVs mostly leant toward reduced-instruction-set computer design. Common processor families there are AVR, PIC, ARM, with a current predominance of ARM’s 32-bit memory-address-register processors. Thus, small UAV embedded systems evolved from the blending terms of microcontrollers, to system-on-a-chip (SOC), and as far as single-board computers (SBC) at present.

UAV hardware is likely to specialize, with increasing numbers of operation per second and hardware acceleration as a background, between, on one hand, calculus speed in exchange for low processing power (time-critical applications), and high-computional-capacity, able to support full operating systems, trading with higher weight on the other hand.

Telecommunication module

Most UAVs integer an old-fashioned radio frequency front-end, that connects the antenna to the analog-to-digital converter and the following computing power.

Sensors

Main sensors :

• Proprioceptive : IMU (gyroscope, accelerometer), compass, altimeter, GPS module, payload measurement…
• Exteroceptive : camera (CMOS, infrared), range sensors (radar, sonar, lidar)…
• Exproprioceptive : internal/external thermometer, gimballed camera...

Degrees of freedom (DOF) refer to both the amount and quality of sensors on-board : 6 DOF stands for 3-axis gyroscopes and accelerometers (a typical inertial measurement unit – IMU), 9 DOF refers to an IMU plus a compass, 10 DOF adds a barometer and 11 DOF usually combine a GPS receiver.^[38]

Actuators

Actuators found in UAVs depend heavily on the aircraft type : digital electronic speed controllers (which control the RPM of the motors) linked to motors/engines and propellers, servomotors (for planes and helicopters mostly), weapons, payload actuators, LEDs, speakers…

UAV-systems hardware chart

While referencing hardware from military projects proves tedious due to classified specificities, commercial and hobbyist systems are easier to overview. Small UAV control system hardware is often named, especially in hobbyists groups, as Flight Controller(FC), Flight Controller Board (FCB) or Autopilot.

Software

The UAV computer software are layered in tiers with different time requirements. The compound of layers is sometimes called flight stack, or autopilot.

Onboard classical operating systems alone are not ideal for flying UAVs : high respond times may be fatal to the aircraft. Thus they may be completed by externally supported middlewares  : RaspberryPis, Beagleboards, etc. shielded with NavIO, PXFMini, etc. or designed from scratch for hard real-time requirements, like Nuttx, preemp-RT Linux, Xenomai, Orocos-Robot Operating System, DDS-ROS 2.0 for instance.

Flight stack overview

Layer	Requirement	Operations	Example
Firmware	Time-critical	From machine code to processor execution, memory access…	ArduCopter-v1.px4
Middleware	Time-critical	Flight control, navigation, radio management...	Cleanflight, ArduPilot
Operating system	Computer-intensive	Optic flow, obstacle avoidance, SLAM, decision-making...	ROS, Nuttx, Linux distributions, Microsoft IOT

A non-exhaustive list of civil-use open-source stacks :

• KKMultiCopter
• ArduCopter
• DroneCode (forked from ArduCopter)
• MultiWii
• BaseFlight (forked from MultiWii)
• CleanFlight (forked from BaseFlight)
• BetaFlight (forked from CleanFlight)
• Paparazzi
• OpenPilot Copter Control
• TauLabs (forked from OpenPilot)
• CrazyFlie

Loop principles

What may differentiate an UAV from a RC model aircraft is the ability to offer sensing, computing power and automation. The aircraft control falls under the relevancy of control theory, with its associated notions. Indeed, an UAV can make use of different automatic controls, mainly designed with loops :

• Open-loops - The simplest design consists of open-loops, typically for motors of small UAVs, which are actuated with sheer input, assuming they will perform as expected (though, for many larger aircrafts, including UAVs, engine control relies on closed-loops).
• Closed-loops – Negative-feedback-loops use sensors to measure the state of the dynamical system, they are the most commonly used for flight control in UAVs. To monitor the execution of the loop, PID control method stands for state-of-the art. Positive feedback has already shown up in particular cases.^[39] Sometimes, feedforward is also employed, transferring the need to close the loop further.^[40]

Flight controls

Flight control is one of the low-layer systems, and is not much different from manned aviation : plane flight dynamics, control and automation, helicopter flight dynamics and controls, and multirotor flight dynamics were in-depth researched long before the rise of UAVs.

The automatic flight control is itself layered in multiple levels of priority.

UAVs can be programmed to perform aggressive manœuvres or landing/perching on inclined surfaces,^[41] or to control flight with varying flight modelisation,^[42][43] such as VTOL designs.

Telecommunication system

A specificity about UAVs is that, being airborne, they rely on wireless communications : teletransmission allows the aircraft control and exchange of other data. Telecommunication channels are mostly achieved with radiofrequency electromagnetic radiations. Telecommunication streams, were historically directed uplink, toward the UAV to monitor the flight. With progress in embedded electronics, downlink was made possible, emitting a signal from the UAV back to the operator, turning both UAV and operator communication systems into transceivers.

In military systems, wich drove the duplex communications, and high-end domestic applications, downlink may also convey payload management status and other advanced features. In the domestic-UAV field, the teletransmission pattern still usually remains as control commands issued from the operator’s transmitter (TX) toward the UAV receiver (RX), downstream consisting mainly in analog video content, from the UAV video emitter (VTX) to the operator’s video receiver (VRX). Telemetry is another kind of downstream link, transmitting status about the aircraft systems to the remote operator. UAVs use also satellite « uplink » to access satellite navigation.

The radio signal from the operator side can be issued from either :

• a ground control – a human operating a radio transmitter/receiver, a smartphone, a tablet, a computer, or the original meaning of a military ground control station (GCS). Recently control from wearable devices,^[44] human movement recognition, human brain waves^[45] was also demonstrated.
• A remote network system, like satellite duplex data links for some major military powers.^[46] Downstream digital video over mobile network has also entered consumer market recently,^[47] while direct UAV control uplink over the celullar mesh is being researched.^[48]
• Another manned aircraft or UAV, serving as a nude relay or as a mobile control station - military manned-unamnned teaming (MUM-T) undergoes important research programs.^[49]

Data transmission, passband modulation, digital radio

While current UAV radio receivers and emitters are separate from the processing unit, digital signal processors may be included soon on the computers which would plug directly to antennas, without transiting by radio frequency middlewares.

Software defined radio (SDR) - Radio packet

SDR hardware evolved from RF front-end to FPGAs, ASICs, and DSP.

Some UAVs use Open System Interconnection layers, to provide Wi-Fi direct and access to ethernet.

Autonomy

As previously described UAV systems, robotics emerged shortly after the invention of transistors and modern electronics. At around the same time that analog-to-digital-modulated proportional radio control appeared, was designed the first digitally programmable robot.

Robotics core modules are the computing power, the actuators and the sensors. Autonomous UAVs, sometimes called flying robots, being developed, arose the need to categorize their autonomy performance, in an UAV-focused manner. The ICAO as mentioned above classifies unmanned aircraft into two types : remotely piloted aircraft, or fully autonomous. Many further classifications have been issued, which, as explained later, can refer to :

• commercial UAV applications, which offer today off-the-shelf autonomous modes that ensure a complete autonomy for determined functions.
• The degree of autonomy – the extent to which the aircraft is independent from the operator assistance - a full pilot authority would stand as a 0% degree of autonomy, while full autonomy would score 100%.
• The level of autonomy – the sophistication of AI, the scope of tasks that the UAV can perform.

Basic principles about autonomous control

A simple way to achieve autonomous control consists in structuring multiple control-loop layers, such as hierarchical control systems. The low-layer loops (i.e. for flight control) can tick as fast as 100 times per second, and the higher-level loops can be required cycles with lengths around a second. The principle is to decompose the aircraft’s behavior into easily manageable « chunks », or states, with knowledgeable transitions between them. HCSs types range from the simple scripts, to finite state machines, behavior trees and hierarchical task planners.

Examples of mid-layer algorithms :

• Path planning: Determining an optimal path for vehicle to follow while meeting certain objectives and mission constraints, such as obstacles or fuel requirements
• Trajectory generation (motion planning): Determining control maneuvers to take in order to follow a given path or to go from one location to another using optimized techniques and processes^[50][51]
• Trajectory regulation: The specific control strategies required to constrain a vehicle within some tolerance to a trajectory.

Evolved UAV hierarchical task planners use methods like state tree searches or, genetic algorithms.^[52]

Autonomous modes

UAV manufacturers often offer built-in autonomous modes.

• Self-level : the aircraft stabilizes its altitude by itself using on-board sensors.
• Hover : altitude stabilization is reinforced by attitude stabilization on the pitch, roll and yaw axis. The latter can be achieved by sensing GNSS coordinates, called alone position hold.
• Loiter, which can be thought of as a relaxed hover mode.
• A feature called by some designers care-free : the aircraft radio control will free the operator from managing the impact of the aircraft heading on the roll and yaw controls.
• Autonomous take-off and landing
• Failsafe : the UAV will land automatically as soon as the control signal is lost.
• Return-to-home
• Follow-me
• GPS waypoint navigation
• Pre-programmed tricks like rolls, loops…
• Flight control modes (beginner, acro…) adjusting flight enveloppe to meet operator experience.

Autonomy degrees

As for general robotics, the amount of independency of the UAV is often referred as degree of autonomy.^[53]

Full degree of autonomy is currently reached for low levels of autonomy akin to simple particular tasks, which can be illustrated with autonomous airborne refueling^[54] or ground-based battery switching for example.

Autonomy levels

Higher-level tasks call for greater computing, sensing and actuating capabilities.

Basic levels of autonomy are handily resolved using proprioceptive sensors, that give information about the aircraft state. Advanced autonomy calls for situational awareness, gaining knowledge about the environment surrounding the aircraft : sensor fusion aggregates different information provided by multiple sensors. Exteroceptive sensors deal with fully external information like range measurements, while exproprioceptive ones correlate internal and external states.^[55]

A mostly military-focused overview of autonomous control levels (ACL) was issued by the US Air force research laboratory, it also encompasses most civilian AI-level scope :^[56]

Autonomous Control Levels chart

Level	Level descriptor	Observe	Orient	Decide	Act
		Perception/Situational awareness	Analysis/Coordination	Decision making	Capability
10	Fully Autonomous	Cognizant of all within battlespace	Coordinates as necessary	Capable of total independence	Requires little guidance to do job
9	Battlespace Swarm Cognizance	Battlespace ingerence - Intent of self and others (allied and foes). Complex/Intense environment - on-board tracking	Strategic group goals assigned Enemy strategy inferred	Distributed tactical group planning Individual determination of tactical goal Individual task planning/execution Choose tactical targets	Group accomplishment of strategic goal with no supervisory assistance
8	Battlespace Cognizance	Proximity inference - Intent of self and others (allied and foes) Reduces dependence upon off-board data	Strategic group goals assigned Enemy tactics inferred ATR	Coordinated tactical group planning Individual task planning/execution Choose target of opportunity	Group accomplishment of strategic goal with minimal supervisory assistance (example : go SCUD hunting)
7	Battlespace Knowledge	Short track awareness - History and predictive battlespace Data in limited range, timeframe and numbers Limited inference supplemented by off-board data	Tactical group goals assigned Enemy trajectory estimated	Individual task planning/execution to meet goals	Group accomplishment of tactical goals with minimal supervisory assistance
6	Real Time Multi-Vehicle Cooperation	Ranged awareness - on-board sensing for long range, supplemented by off-board data	Tactical group goals assigned Enemy trajectory sensed/estimated	Coordinated trajectory planning and execution to meet goals - group optimization	Group accomplishment of tactical goals with minimal supervisory assistance Possible : close air space separation (+/-100yds) for AAR, formation in non-threat conditions
5	Real Time Multi-Vehicle Coordination	Sensed awareness - Local sensors to detect others, Fused with off-board data	Tactical group plan assigned RT Health Diagnosis Ability to compensate for most failures and flight conditions ; Ability to predict onset of failures (e.g. Prognostic Health Mgmt) Group diagnosis and resource management	On-board trajectory replanning - optimizes for current and predictive conditions Collision avoidance	Self accomplishment of tactical plan as externally assigned Medium vehicle airspace separation (100's of yds)
4	Fault/Event Adaptative Vehicle	Deliberate awareness - allies communicate data	Tactical group plan assigned Assigned Rules of Engagement RT Health Diagnosis ; Ability to compensate for most failures and flight conditions - inner loop changes reflected in outer loop performance	On-board trajectory replanning - event driven Self resource management Deconfliction	Self accomplishment of tactical plan as externally assigned Medium vehicle airspace separation (100's of yds)
3	Robust Response to Real Time Faults/Events	Health/status history & models	Tactical group plan assigned RT Health Diagnosis (What is the extent of the problems?) Ability to compensate for most failures and flight conditions (i.e. adaptative inner loop control)	Evaluate status vs required mission capabilities Abort/RTB is insufficient	Self accomplishment of tactical plan as externally assigned
2	Changeable mission	Health/status sensors	RT Health diagnosis (Do I have problems?) Off-board replan (as required)	Execute preprogrammed or uploaded plans in response to mission and health conditions	Self accomplishment of tactical plan as externally assigned
1	Execute Preplanned Mission	Preloaded mission data Flight Control and Navigation Sensing	Pre/Post flight BIT Report status	Preprogrammed mission and abort plans	Wide airspace separation requirements (miles)
0	Remotely Piloted Vehicle	Flight Control (attitude, rates) sensing Nose camera	Telemetered data Remote pilot commands	N/A	Control by remote pilot

Medium levels of autonomy like reactive autonomy, and high levels using cognitive autonomy have already been achieved to some extent and are very active research fields.

Reactive autonomy

Reactive autonomy, such as collective flight, real-time collision avoidance, wall following and corridor centring, relies on telecommunication, and situational awareness provided by range sensors : optic flow,^[57] lidars (light radars), radars, sonars.

Most of the range sensors analyze elecromagnetic radiations, reflected on the environment and coming to the sensor. The cameras (for visual flow) stands as simple receivers of radiations in the visible spectrum and near it, whereas Lidars, radars, and sonars (with sound mechanical waves) emit and receive waves, and measure the time taken by the ondulations to perform the round-trip. The primary source of wave emission is external for cameras, and internal for the rest - the environment in all cases being the secondary source : one major pros with cameras in UAVs is that they do not require emitting power, they are much less power-consuming on already power-restrained platforms.

Radars and sonars are mostly used for large UAVs in the militaries. Audio power detection from other UAVs’ engines, magnetic or heat detection are eventually another kind of range sensing.

Reactive autonomy has in some forms already reached consumer market : it is predicted to be widely deployed within less than a decade.^[55]

Cognitive autonomy

A roadmap for a more advanced cognitive autonomy would include :

Simultaneous localization and mapping

SLAM combines odometry and external data to represent the world and the position of the UAV in it. Contrary to indoor SLAM, high-altitude outdoor SLAM with UAVs does not require large vertical fields-of-view, can rely on GPS coordinates (which makes it quite no longer SLAM but simple mapping), and can allow large aircraft dimensions, with high payloads and endurance -mostly with planes : that explains why the latter is much further deployed than the former.^[58]

Two main concomitting research fields in SLAM for UAVs are photogrammetry and LIDARs, especially in low-altitude and indoor 3D environments.

• Indoor photogrammetric and stereophotogrammetric SLAM has been demonstrated with quadcopters.^[59]
• Lidar 3D mapping hovering platforms with heavy, costly and gimbaled traditional laser platforms have been proven viable numerous times. The main issue belongs in rising from 2D sensing to 3D point clouds.^[60] LED range-finding applications are also commercialized but feature low-distance sensing capabilities. Some cutting-edge developments likely to further miniaturize lidar systems might be hybridization technologies between light emission and computing power: phased array of spatial light modulators,^[61][62] and frequency-modulated-continuous-wave (FMCW) MEMS-tunable vertical-cavity surface-emitting lasers (VCSELs).^[63] Such lidars might withdraw the major flaws of current laser-gimbaled lidars : production cost, 2D limitation, power-to-range ratio, weight and dimensions.

Swarming

Robot swarming refers to networks of agents able to dynamically reconfigur as some elements leave or enter the collective. They provide greater flexibility than multi-agent cooperation recurring to a maximal decentralization. Swarming may open the path to the sensor fusion next-level : data fusion. While some bio-inspired flight swarms already use steering behaviors and flocking, more advanced UAVs-swarm patterns, path planning or attacks are being researched.

Future military potential of swarms (USA)

In the military sector, Predators and Reapers are tailor-made for counterterrorism operations and in war zones in which the enemy lacks sufficient firepower to shoot them down, but are not designed to withstand antiaircraft defenses or air-to-air combat; in September 2013, the chief of the Air Combat Command stated that current UAVs were "useless in a contested environment" unless manned aircraft were put there to protect them.[167] A 2012 Congressional Research Service (CRS) report indicated that in the future, UAVs may be able to perform a variety of tasks beyond their present roles in intelligence, surveillance, reconnaissance, and strikes; the CRS report listed air-to-air combat ("a more difficult future task") as possible future undertakings.[168] The U.S. Department of Defense's Unmanned Systems Integrated Roadmap FY2013-2038 foresees UAVs having a more important place in combat, recognizing that the near future will involve making sure the technology works at all, before exploiting their potential in the following decade.[169] Beyond solving technical issues, issues to be resolved include human-UAV interaction, managing expected increases in amounts of information generated by UAV swarms, transitioning from direct human control to UAVs' automatic adaptation to changing conditions, and developing UAV-specific munitions.[169] Indeed, DARPA’s project of systems of systems,^[64] or General Atomics may augur future warfare scenarios, the latter disclosing Avenger swarms equipped with HELLADS.^[65]

Decision making

UAVs able to take high-level decisions on their own are researched with fuzzy logic, preference-based planning, multi-criteria decision analysis for example.

Learning capabilities

The application to UAVs of the ever-deeper distributed neural networks are promising to many.^[55]

Market trends

Though global forecasts appear hardly reliable, especially due to regulation concerns, the military UAV market will stay far ahead of the civil market with an expected $10bn out of $13bn in 2024.^[67]

The UAV global military market is still currently dominated by the United States and Israel, the pioneers in that field. USA held a 60% military-maket share in 2006 and a projected 70% in 2016. It operated over 9000 UAVs in 2014. Israel has been standing as the most important military exporter in the past fifteen years (citations time and prev UAV) – the military exports are very rare and the markets mostly national. Northrop Grumman and General Atomics are the dominant manufacturers in this industry on the strength of the Global Hawk and Predator/Mariner systems. However, China has committed to great effort and its first manufacturer is believed to become the leading global producer of UAVs by 2023.^[68]

Reports^[69] forecasts the small unmanned-aircraft-system market to reach $8bn in 2019, including services and applications : the professional and hobbyist share representing $1.1bn and the commercial share $5.2bn.^[70] The estimated leading civil-UAV companies are currently the Chinese DJI with $500m global sales, the French Parrot with $110m, and the US 3DRobotics with $21.6m in 2014.^[71]

Some universities offer now UAS research and training programs or academic degrees.^[72]

Development considerations

Animal imitation – Ethology

Flapping-wing ornithopters, imitating birds or insects, are a specific research field in microUAVs. Their inherent stealth highly qualify them to perform spying missions.

The Nano Hummingbird is one of various examples commercialized a few years ago, whereas sub-1g microUAVs inspired by flies, on a tethered power at the moment, perform landing on vertical surfaces already.^[73]

Some government agencies are allegedly developing fly-looking killer UAVs.^[74]

Research also focuses on miniature optic-flow sensors, called ocellis, mimicking the compound eyes of insects formed by dozens of facets, which can transmit data to neuromorphic chips able to treat optic flow as well as light intensity discreapancies.

Endurance

The endurance of a UAV is not constrained by the physiological limitations of a human pilot. The maximum flight duration of unmanned aerial vehicles varies widely.

Because of the small size, weight, low vibration and high power to weight ratio, Wankel rotary engines are used in many large UAV aircrafts.[191][192] Additionally: the engine rotors cannot seize; the engine is not susceptible to shock-cooling during descent and it does not require an enriched fuel mixture for cooling at high power. The attributes of the Wankel engine transpire into less fuel usage in UAVs giving greater range or a higher payload.[193]

Hyrbid power sources between electricity and fuel,^[75] hydrogen power^[76][77] are seeing developments too, largely extending the endurance of small UAVs, up to several hours.

Micro air vehicles endurance is best achieved with flapping-wing UAVs, followed by planes, and multirotors standing as last, due to lower Reyold numbers.^[55]

Solar-electric UAVs, a concept originally championed by the AstroFlight Sunrise in 1974, have achieved endurance of several weeks.[194][195][196][197][198]

Solar-powered atmospheric satellites ("atmosats") designed for operating at altitudes exceeding 20 km (12 miles, or 60,000 feet) for as long as five years would perform duties more economically and with more versatility than low earth orbit satellites.[170] Likely applications include weather monitoring, disaster recovery, earth imaging, and communications.[170] [Google 5G]

Electric UAVs powered by microwave power transmission - in the same way a RFID reader can activate a tag to make it answer back [199], or laser power beaming[200] are other proposed solutions to the endurance challenge.

Another of the uses for a high endurance UAV would be to "stare" at the battlefield for a long period of time (ARGUS-IS, Gorgon Stare, Integrated Sensor Is Structure) to produce a record of events that could then be played backwards to track where improvised explosive devices (IEDs) came from.

Notable high endurance flights

UAV	Flight time	Date	Notes
Boeing Condor	58 hours 11 minutes	1989	The aircraft is currently in the Hiller Aviation Museum. [78]
GNAT-750	40 hours	1992	[79][80]
TAM-5	38 hours 52 minutes	11 August 2003	Smallest UAV to cross the Atlantic [81]
QinetiQ Zephyr Solar Electric	54 hours	September 2007	[82][83]
RQ-4 Global Hawk	33.1 hours	22 March 2008	Set an endurance record for a full-scale, operational unmanned aircraft.[84]
QinetiQ Zephyr Solar Electric	82 hours 37 minutes	28–31 July 2008	[85]
QinetiQ Zephyr Solar Electric	336 hours 22 minutes	9–23 July 2010	[86]

Liability

Liability improvements target both UAVs and UAV swarms, using resilience engineering and fault tolerance.

Individual liability covers robustness of flight controllers, to ensure safety without adding too much redundancy so as staying cheap and light, hitting the notions of modular and distributed avionics.^[87] Besides, dynamic assessment of flight envelope allows damage-resilient UAVs, using non-linear analysis with ad-hoc designed loops or neural networks.^[88] UAV software liability is bending toward the design and certifications of manned avionics software.^[89]

Further research toward swarm resilience focuses on keeping the swarm operational functionalities, reconfiguring the task allocation if one of the UAVs were to default.^[90]

Uses

Beyond the military applications of UAVs with which "drones" became most associated, numerous civil aviation uses have been developed, including aerial surveying of crops,^[91] acrobatic aerial footage in filmmaking,^[91] search and rescue operations,^[91] inspecting power lines and pipelines,^[92] counting wildlife,^[92] delivering medical supplies to remote or otherwise inaccessible regions,^[93] with some manufacturers rebranding the technology as "unmanned aerial systems" (UASs) in preference over the military-connotative term "drones".^[91] Further uses include reconnaissance operations,^[94][95] cooperative environment monitoring,^[96] border patrol missions,^[94][97] convoy protection,^[98] forest fire detection,^[94] surveillance,^[94][99] coordinating humanitarian aid,^[100] plume tracking,^[101] search & rescue missions,^[94] detection of illegal hunting,^[102] land surveying,^[103] fire and large-accident investigation,^[103] landslide measurement,^[103] illegal landfill detection,^[103] and crowd monitoring.^[103]

UAVs have been used by military forces, civilian government agencies, businesses, and private individuals. In the United States, for example, government agencies use UAVs such as the RQ-9 Reaper to patrol the nation's borders, scout property, and locate fugitives.^[104] One of the first authorized for domestic use was the ShadowHawk UAV in service in Montgomery County, Texas, and is being used by their SWAT and emergency management offices.^[105]

Private citizens and media organizations use UAVs for surveillance, recreation, news-gathering, or personal land assessment. Occupy Wall Street journalist Tim Pool uses what he calls an "occucopter" for live feed coverage of Occupy movement events.^[106] The "occucopter" is an inexpensive radio-controlled quadcopter with cameras attached and controllable by Android devices or iOS. In February 2012, an animal rights group used a MikroKopter hexacopter to film hunters shooting pigeons in South Carolina. The hunters then shot the UAV down.^[107] UAVs also have been shown to have many other civilian uses, such as in agriculture, movies, and the construction industry.^[108] In 2014, a drone was used in search and rescue operations to successfully locate an elderly gentleman with dementia who went missing for 3 days.^[109] In March 2015, the SXSW music festival in Austin, Texas banned drones, citing Wi-Fi bandwidth congestion and safety concerns.^[110][111]

Military Uses

Reconnaissance

The Tu-141 "Swift" reusable Soviet operational and tactical reconnaissance drone is intended for reconnaissance to a depth of several hundred kilometers from the front line at supersonic speeds.^[112] The Tu-123 "Hawk" is a supersonic long-range reconnaissance drone (UAV) intended for conducting photographic and signals intelligence to a distance of 3200 km; it was produced since 1964.^[113] The La-17P (UAV) is a reconnaissance UAV produced since 1963.^[114] Since 1945, the Soviet Union also produced "doodlebug".^[115] There are 43 known Soviet UAV models.^[116]

In 2013, the U.S. Navy launched a UAV from a submerged submarine, the first step to "providing mission intelligence, surveillance, and reconnaissance capabilities to the U.S. Navy’s submarine force."^[117]

Armed attacks

When the United States entered the global war on terror, U.S. military officials found difficulty in fighting irregular warfare. The U.S. military turned to Harlan Ullman and James Wade’s Shock and Awe doctrine, which states "the most efficient way of fighting asymmetric threats in irregular warfare is to conduct fast and destructive operations in order to incapacitate the enemy" ^[118]

MQ-1 Predator UAVs armed with Hellfire missiles have been used by the U.S. as platforms for hitting ground targets. Armed Predators were first used in late 2001 from bases in Pakistan and Uzbekistan, mostly aimed at assassinating high-profile individuals (terrorist leaders, etc.) inside Afghanistan. Since then, many cases of such attacks have been reported taking place in Afghanistan, Pakistan, Yemen, and Somalia.^[119] 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 take place in countries deemed friendly and without the official permission of those countries.^{[120][121][122][123]}

The "unmanned" aspect of UAVs has raised moral concerns. Some believe that the asymmetry of fighting humans with machines that are controlled from a safe distance lacks integrity and honor that was once valued during warfare. Others feel that if such technology is available, then a moral duty exists to employ it to save as many lives as possible.^[124]

Defense against UAVs

The United States armed forces currently have no defense against low-level drone attack, but the Joint Integrated Air and Missile Defense Organization is working to repurpose existing systems to defend American forces.^[125] Two German companies are developing 40-kW lasers to damage UAVs.^[126] Three British companies have jointly developed a system to track and disrupt the control mechanism for small UAVs.^[127]

As authorities across globe scramble for effective and advanced ways to counter the increasing number of rogue drones buzzing around over skies, Dutch National Police have come up with something a little more unusual: the mighty eagle.^[128]

Civilian casualties

In March 2009, The Guardian reported allegations 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.^[129] In June, Human Rights Watch investigated six UAV attacks that were reported to have resulted in civilian casualties and alleged 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.^{[130][131][132]}

In 2009, Brookings Institution reported that in the United States-led drone attacks in Pakistan, ten civilians died for every militant killed.^[133][134] A former ambassador of Pakistan said that American UAV attacks were turning Pakistani opinion against the United States.^[135] The website PakistanBodyCount.Org shows 1,065 civilian deaths between 2004 and 2010.^[136] According to a 2010 analysis by the New America Foundation 114 UAV-based missile strikes in northwest Pakistan from 2004 killed between 830 and 1,210 individuals, around 550 to 850 of whom were militants.^[137] In October 2013 the Pakistani government revealed that since 2008 there had been 317 drone strikes that killed 2,160 Islamic militants and 67 civilians - far less than previous government and independent organization calculations.^[138]

Targets for military training

Since 1997, the U.S. military has used more than 80 F-4 Phantoms converted into robotic planes for use as aerial targets for combat training of human pilots.^[139] The F-4s were supplemented in September 2013 with F-16s as more realistically maneuverable targets.^[139]

UAVs in the US military

As of January 2014, the U.S. military operates a large number of unmanned aerial systems: 7,362 RQ-11B Ravens; 145 AeroVironment RQ-12A Wasps; 1,137 AeroVironment RQ-20A Pumas; and 306 RQ-16 T-Hawk Small UAS systems and 246 Predators and MQ-1C Grey Eagles; 126 MQ-9 Reapers; 491 RQ-7 Shadows; and 33 RQ-4 Global Hawk large systems.^[140] The use of drones in the military is expected to increase in coming years because UAVs curb defense spending. The MQ-9 Reaper costs $12 million while an F-22 costs over $120 million.^[141]

Civil uses

Hobby and recreational use

Model aircraft, which are now included in the definition of Small UAS (sUAS) by the FAA, have been safely flown by hobbyists since the earliest days of manned flight. In the United States, hobby and recreational use of such sUAS is permitted as set out in section 336 of Public Law 112-95. Specifically:(a) The aircraft is flown strictly for hobby or recreational use; (b) The aircraft is operated in accordance with a community-based set of safety guidelines and within the programming of a nationwide community-based organization; (c) The aircraft is limited to not more than 55 pounds unless otherwise certified through a design, construction, inspection, flight test, and operational safety program administered by a community-based organization; (d) The aircraft is operated in a manner that does not interfere with and gives way to any manned aircraft; and (e) When flown within 5 miles of an airport, the operator of the aircraft provides the airport operator and the airport air traffic control tower (when an air traffic facility is located at the airport) with prior notice of the operation.^[142] The Academy of Model Aeronautics serves as community based organization which maintains a set of operational safety guidelines with a long proven history of effectiveness and safety.

Commercial aerial surveillance

Aerial surveillance of large areas is made possible with low-cost UAV systems. Surveillance applications include livestock monitoring, wildfire mapping, pipeline security, home security, road patrol, and antipiracy. The trend for the use of UAV technology in commercial aerial surveillance is expanding rapidly with increased development of automated object detection approaches.^[143]

Professional aerial surveying

UAS technologies are used worldwide as aerial photogrammetry and LiDAR platforms.

Commercial and motion picture filmmaking

For commercial drone camerawork inside the United States, industry sources state that usage is largely at the de facto consent – or benign neglect – of local law enforcement. Use of UAVs for filmmaking is generally easier on large private lots or in rural and exurban areas with fewer space concerns. In certain localities such as Los Angeles and New York, authorities have actively interceded to shut down drone filmmaking efforts due to concerns driven by safety or terrorism.^{[144][145][146]}

In June 2014, the FAA said it had received a petition from the Motion Picture Association of America seeking approval for the use of drones in video and filmmaking. Seven companies behind the petition argued that low-cost drones could be used for shots that would otherwise require a helicopter or a manned aircraft, which would reduce costs. Drones are already used by movie makers and media in other parts of the world.

Drones were used in the 2014 Winter Olympics in Sochi for filming skiing and snowboarding events. Some advantages of using unmanned aerial vehicles in sports are that they allow video to get closer to the athletes, and they are more flexible than cable-suspended camera systems.^[147]

Journalism

Some journalists in the United States are interested in using drones for newsgathering. The College of Journalism and Mass Communications at the University of Nebraska-Lincoln has established the Drone Journalism Lab.^[148] The University of Missouri also has created the Missouri Drone Journalism Program.^[149] The Professional Society of Drone Journalists was established in 2011 and describes itself as "the first international organization dedicated to establishing the ethical, educational, and technological framework for the emerging field of drone journalism."^[150] Drones have been especially useful in covering disasters such as typhoons.^[151] A coalition of 11 news organizations is working with the Mid-Atlantic Aviation Partnership at Virginia Tech on how reporters could use unmanned aircraft to gather news.^[152]

Law enforcement

Many police departments in India have procured drones for law and order and aerial surveillance.^{[153][154][155][156]}

UAVs have been used for domestic police work in Canada and the United States;^[157][158] a dozen US police forces had applied for UAV permits by March 2013.^[33] In 2013, the Seattle Police Department’s plan to deploy UAVs was scrapped after protests.^[159] UAVs have been used by U.S. Customs and Border Protection since 2005.^[160] with plans to use armed drones.^[161] The FBI stated in 2013 that they own and use UAVs for the purposes of "surveillance".^[162]

In 2014, it was reported that five English police forces had obtained or operated unmanned aerial vehicles for observation.^[163] Merseyside Police caught a car thief with a UAV in 2010, but the UAV was later lost during a training exercise^[164] and the police stated the UAV would not be replaced due to operational limitations and the cost of staff training.^[164]

In August 2013, the Italian defence company Selex ES provided an unarmed surveillance drone to be deployed in the Democratic Republic of Congo to monitor movements of armed groups in the region and to protect the civilian population more effectively.^[165]

Search and rescue

UAVs were used in search and rescue after hurricanes struck Louisiana and Texas in 2008. Predators, operating between 18,000 and 29,000 feet above sea level, performed search and rescue and damage assessment. Payloads carried were an optical sensor and a synthetic aperture radar. The latter can provide images through clouds, rain, or fog, and in daytime or nighttime conditions, all in real time. Photos taken before and after the storm are compared, and a computer highlights areas of damage.^[166][167] Micro UAVs, such as the Aeryon Scout, have been used to perform search and rescue activities on a smaller scale, such as the search for missing persons.^[168]

UAVs have been tested as airborne lifeguards, locating distressed swimmers using thermal cameras and dropping life preservers to swimmers.^[169][170]

Demining

The Space Assets for Demining Assistance program from the European Space Agency aims to improve the socioeconomic impact of land release activities in mine action.^[171] It is developing and has tested UAV technology for demining in Bosnia-Herzegovina.^[172][173]

Scientific research

Unmanned aircraft are especially useful in penetrating areas that may be too dangerous for manned aircraft. The U.S. National Oceanic and Atmospheric Administration began using the Aerosonde unmanned aircraft system in 2006 as a hurricane hunter. The 35-pound system can fly into a hurricane and communicate near-real-time data directly to the National Hurricane Center. Beyond the standard barometric pressure and temperature data typically culled from manned hurricane hunters, the Aerosonde system provides measurements from closer to the water’s surface than previously captured. NASA later began using the Northrop Grumman RQ-4 Global Hawk for extended hurricane measurements.

Conservation

In 2011, Lian Pin Koh and Serge Wich conceived the idea of using UAV for conservation-related applications, before coining the term 'Conservation Drone' in 2012.^[174]

By 2012 the International Anti-Poaching Foundation was using UAVs.^[175]

Anti Poaching

In June 2012, World Wide Fund for Nature (WWF) announced it will begin using UAVs in Nepal to aid conservation efforts following a successful trial of two aircraft in Chitwan National Park, with ambitions to expand to other countries, such as Tanzania and Malaysia. The global wildlife organization plans to train ten personnel to use the UAVs, with operational use beginning in the fall.^[176][177] In August 2012, UAVs were used by members of the Sea Shepherd Conservation Society in Namibia to document the annual seal cull.^[178] In December 2013, the Falcon UAV was selected by the Namibian Govt and WWF to help combat rhino poaching.^[179] The drones will be monitoring rhino populations in Etosha National Park and will use RFID sensors.^[180]

In 2012, the WWFund supplied two FPV Raptor 1.6 UAVs^[181] to the Nepal National Parks. These UAVs were used to monitor rhinos, tigers, and elephants and deter poachers.^[182] The UAVs were equipped with time-lapse cameras and could fly for 18 miles at 650 feet.^[183]

In December 2012, the Kruger National Park started using a Seeker II UAV against rhino poachers. The UAV was loaned to the South African National Parks authority by its manufacturer, Denel Dynamics of South Africa.^[184][185]

Anti-whaling activists used an Osprey UAV (made by Kansas-based Hangar 18) in 2012 to monitor Japanese whaling ships in the Antarctic.^[186]

In 2012, the Ulster Society for the Prevention of Cruelty to Animals used a quadcopter UAV to deter badger baiters in Northern Ireland.^[187] In March 2013, the British League Against Cruel Sports announced they had carried out trial flights with UAVs and planned to use a fixed-wing OpenRanger and an "octocopter" to gather evidence to make private prosecutions against illegal hunting of foxes and other animals.^[184] The UAVs were supplied by ShadowView. A spokesman for Privacy International said that "licensing and permission for drones is only on the basis of health and safety, without considering whether privacy rights are violated."^[184] CAA rules prohibit flying a UAV within 50 m of a person or vehicle.^[184][188]

In Pennsylvania, Showing Animals Respect and Kindness used drones to monitor people shooting at pigeons for sport.^[189] One of their octocopter drones was shot down by hunters.^[190]

In March 2013, the Times published a controversial story that UAV conservation nonprofit ShadowView, founded by former members of Sea Shepherd Conservation Society, had been working for several months with antihunting charity the League Against Cruel Sports to expose illegal fox hunting in the UK.^[191] Hunt supporters have argued that using UAVs to film hunting is an invasion of privacy.^[192]

In 2014, Will Potter proposed using drones to monitor conditions on factory farms. The idea is to circumvent ag-gag prohibitions by keeping the drones on public property, but equipping them with cameras sensitive enough to monitor activities on the farms.^[193] Potter raised nearly $23,000 in 2 days for this project on Kickstarter.^[193]

Surveying

Oil, gas, and mineral exploration and production

UAVs can be used to perform geophysical surveys, in particular geomagnetic surveys^[194] where the processed measurements of the Earth's differential magnetic field strength are used to calculate the nature of the underlying magnetic rock structure. A knowledge of the underlying rock structure helps trained geophysicists to predict the location of mineral deposits. The production side of oil and gas exploration and production entails the monitoring of the integrity of oil and gas pipelines and related installations. For above-ground pipelines, this monitoring activity could be performed using digital cameras mounted on one or more UAVs.^[195]

Disaster relief

Drones can help in disaster relief by gathering information from across an affected area to build a picture of the situation and give recommendations to direct resources.^[196]

T-Hawk^[197] and Global Hawk^[198] drones were used to gather information about the damaged Fukushima Number 1 nuclear plant and disaster-stricken areas of the Tōhoku region after the March 2011 tsunami.

Archaeology

In Peru, archaeologists use drones to speed up survey work and protect sites from squatters, builders, and miners. Small drones helped researchers produce three-dimensional models of Peruvian sites instead of the usual flat maps – and in days and weeks instead of months and years.^[199]

Drones have replaced expensive and clumsy small planes, kites, and helium balloons. Drones costing as little as £650 have proven useful. In 2013, drones flew over at least six Peruvian archaeological sites, including the colonial Andean town Machu Llacta 4,000 m (13,000 ft) above sea level. The drones continue to have altitude problems in the Andes, leading to plans to make a drone blimp.^[199]

An archaeologist said, "You can go up three metres and photograph a room, 300 metres and photograph a site, or you can go up 3,000 metres and photograph the entire valley."^[199]

In September 2014, drones weighing about 0.5 kg were used for 3D mapping of the above-ground ruins of the Greek city of Aphrodisias.^[200]

Venezuela

In 2012, Cavim, the state-run arms manufacturer of Venezuela, claimed to be producing its own UAV as part of a system to survey and monitor pipelines, dams, and other rural infrastructure. The UAV had a range of 100 km, a maximum altitude of 3,000 m, could fly for 90 minutes, and measured 3 by 4 m.^[201][202]

Cargo transport

UAVs can transport medicines and medical samples into and out of remote or otherwise inaccessible regions.^[93]

Initial attempts at commercial use of UAVs, such as the Tacocopter company for food delivery, were blocked by FAA regulation.^[203] A 2013 announcement that Amazon was planning deliveries using UAVs was met with skepticism.^[204]

In 2013, in a research project of DHL, a small quantity of medicine was delivered via a UAV.^[205][206]

In 2014, the prime minister of the United Arab Emirates announced that the UAE planned to launch a fleet of UAVs^[207] to deliver official documents and supply emergency services at accidents.^[208]

Google revealed in 2014 it had been testing UAVs for two years. The Google X program aims to produce drones that can deliver items.^[209]

July 16, 2015, A NASA Langley fixed-wing Cirrus SR22 aircraft, flown remotely from the ground, operated by NASA's Langley Research Center in Hampton and a hexacopter drone delivered pharmaceuticals and other medical supplies to an outdoor free clinic at the Wise County Fairgrounds, Virginia. The aircraft picked up 10 pounds of pharmaceuticals and supplies from an airport in Tazewell County in southwest Virginia and delivered the medicine to the Lonesome Pine Airport in Wise County. The aircraft had a pilot on board for safety. The supplies went to a crew, which separated the supplies into 24 smaller packages to be delivered by small, unmanned drone to the free clinic, during a number of flights over two hours. A company pilot controlled the hexacopter, which lowered the pharmaceuticals to the ground by tether. Health care professionals received the packages, then distributed the medications to the appropriate patients.^[210]

Farms

Japanese farmers have been using Yamaha's R-50 and RMAX unmanned helicopters to dust their crops since 1987.^[211][212] Some farming initiatives in the U.S. use UAVs for crop spraying, as they are often cheaper than a full-sized helicopter.

UAV is also now becoming the invaluable tool by farmers in other aspect of farming, such as monitoring livestock, crops and water levels. Farmers also use it for fast data gathering on crop health, improving yield plus reducing input cost. Sophisticated UAV has also been used to create 3D image of the landscape to plan for future expansions and upgrading ^[213]

Existing UAVs

UAVs are being developed and deployed by many countries around the world. Due to their fast proliferation, there is no comprehensive list of current UAV systems or current holders.^[214] For a list of models by country, see: List of unmanned aerial vehicles. The use of unmanned aerial systems, however, is not limited to state powers: non-state actors can also build, buy and operate these combat vehicles.^[31]

The export of UAVs or technology capable of carrying a 500 kg payload at least 300 km is restricted in many countries by the Missile Technology Control Regime.

China has exhibited some UAV designs, but its ability to operate them is limited by the lack of high endurance domestic engines, satellite infrastructure, and operational experience.^[215]

Events involving UAVs

Ethical concerns and regulation

Ethical concerns

The uses of UAVs raise several issues about their impact on humans.

UAVs can threaten airspace security in numerous ways, such as the concern about allow a flying robot to take the decision to kill, the worrying use of UAVs carrying explosive payloads, the hazards from UAVs kinetic energy during crashes, privacy intrusion or even noise pollution.

The "unmanned" aspect of UAVs has raised moral concerns. Some believe that the asymmetry of fighting humans with machines that are controlled from a safe distance lacks integrity and honor that was once valued during warfare. Others feel that if such technology is available, then a moral duty exists to employ it to save as many lives as possible.^[216]

Military analysts, policy makers, and academics debate the benefits and risks of lethal autonomous robots (LARs), which would be able to select targets and fire without approval of a human. Some contend that LAR drones would be more precise, less likely to kill civilians, and less prone to being hacked.^[217] Heather Roff replies that LARs may not be appropriate for complex conflicts, and targeted populations would likely react angrily against them.^[217] Will McCants argues that the public would be more outraged by machine failures than human error, making LARs politically implausible.^[217] According to Mark Gubrud, claims that drones can be hacked are overblown and misleading, and moreover, drones are more likely to be hacked if they're autonomous, because otherwise the human operator would take control: "Giving weapon systems autonomous capabilities is a good way to lose control of them, either due to a programming error, unanticipated circumstances, malfunction, or hack, and then not be able to regain control short of blowing them up, hopefully before they've blown up too many other things and people."^[218]

Regulation

Ethical concerns and UAV-related accidents have driven states to regulate the use of UAVs.

To operate a UAV for nonrecreational purposes in the United States, according to the Federal Aviation Administration (FAA), users must obtain a Certificate of Authorization.^[219] The use of UAVs for law-enforcement purposes is also regulated at a state level. For commercial use in the United States, the FAA mandates that operators must first petition for an exemption under Section 333 to be approved for commercial use cases. ^[220]

The Irish Aviation Authority policy is that unmanned aerial systems may not be flown without the operator receiving a specific permission from the IAA.^[221] New regulations, including a registry of UAVs over 1 kg were introduced in December 2015.^[222][223]

In April 2014, the South African Civil Aviation Authority announced that it would clamp down on the illegal flying of UAVs in South African airspace.^[224]

In Oct 2015, the US Department of Transportation and FAA indicated a task force would be formed to determine the requirements for registering commercial drones.^[225]

In December 2015, the FAA announced that Americans would have to register all drones weighing over 250 grams.^[226] The FAA's Interim Rule can be accessed here. This regulation went into effect on December 21, 2015 and requires that hobby type UAV's between 250 grams and 55 pounds need to be registered no later than February 19, 2016.^[227] The FAA's registration portal for drones can be accessed here.

Notable requirements of the new FAA UAV registration process include:

• Effective December 21, 2015, if the UAV has never been operated in U.S. airspace (i.e. its first flight outside), eligible owners must register their UAV's prior to flight. If the UAV previously operated in U.S. airspace, it must be registered by February 19, 2016.
• In order to use the registration portal, visitors must be 13 years of age or older. If the owner is less than 13 years old, then a parent or other responsible person must do the FAA registration.
• Each registrant will receive a certificate of aircraft registration and a registration number and all UAV's must be marked with the FAA issued registration number.^[228]
• The FAA registration requires a $5 fee, though the FAA is waiving the fee for the first 30 days of the new registration period - until January 20, 2016. The registration is good for 3 years, but can be renewed for an additional 3 years at the $5 rate.^[229]

The new FAA rule provides that a single registration applies to as many UAVs as an owner/operator owns or operates. Failure to register can result in civil penalties of up to $27,500, and criminal penalties which could include fines up to $250,000 and/or imprisonment for up to three years.^[230]

UAVs in popular culture

• Toys (1992) depicts unwitting child soldiers in training to fly UAVs.
• UAVs were used in episodes of the science-fiction television series, Stargate SG-1 (1997-2007) and Dark Angel (2000-2002).
• A UCAV AI, called EDI, was central to the sci-fi action film Stealth (2005).
• UAVs also feature in video games, such as Tom Clancy's Ghost Recon (2001-), Battlefield (2002-), Call of Duty (2003-), F.E.A.R. (2005), and inFamous (2009).^[231]
• An MQ-9 reaper controlled by a rogue supercomputer appears in the film Eagle Eye (2008).
• The hapless would-be terrorists in the film Four Lions (2010) are targeted by and attempt to shoot down an RQ-1 Predator.
• The Bourne Legacy (2012 film) features a Predator UAV pursuing the protagonists.
• An episode of the TV show Castle, first broadcast in May 2013, featured a UAV hacked by terrorists.^[232]
• The British movie Hummingbird (2013) ends with ambiguity as to whether the main protagonist is taken down by a drone or not.
• 24: Live Another Day, the ninth season of "24", revolves around the usage of UAVs resembling the BAE Systems Taranis by terrorists who have created a device to override control from a military base.
• The film Good Kill features the life of an USAF drone pilot.

UAE Drones for Good Award

In 2014, the government of the United Arab Emirates announced an annual international competition and $1 million award, UAE Drones for Good, aiming to encourage useful and positive applications for UAV technology in applications such as in search and rescue, civil defence and conservation. The 2015 award was won by Swiss company Flyability, the 2016 edition awarded Loon Copter's sea-hybrid UAV.^[233]

See also

References

External links

Wikimedia Commons has media related to Unmanned aerial vehicles.

Wikiquote has quotations related to: Drones

News and stories :

• SUAS news, breaking news for professional UAV operators
• Dronelife, UAV news
• Sapiendrone, the most important stories about UAV's

Research and groups :

• Center for Unmanned Aircraft Systems, a National Science Foundation Industry & University Cooperative Research Center
• UVS International Non Profit Organization representing manufacturers of unmanned vehicle systems (UVS), subsystems and critical components for UVS and associated equipment, as well as companies supplying services with or for UVS, research organizations and academia.
• The Remote Control Aerial Platform Association, commercial UAS operators

Civil - hobbyist :

• DIYDrones, forum for drone makers, with a useful glossary :
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• Sky View Photography, New Zealand Commercial Drone Photography

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