exploiting unmanned aircraft systems

8/6/2019 Exploiting Unmanned Aircraft Systems

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AIAA Infotech@Aerospace 2010

Exploiting Unmanned Aircraft Systems

Dr. Werner J.A. Dahm

USAF Chief ScientistAir Force Pentagon

Headquarters U.S. Air Force 21 April 2010

Their Role in Future Military Operations

and the Emergent Technologies that will Shape Their Development



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Current Unmanned Aircraft Systems of the U.S. Air Force and DoD

U.S. Army

MQ-1C WarriorRQ-7 Shadow

RQ-11 Raven

Wasp III BATMAV

U.S. Navy / Marines

RQ-2 Pioneer

RQ-11 Raven Scan Eagle

RQ-8 Fire Scout

U.S. Air Force RQ-4 Global Hawk

MQ-1 PredatorMQ-9 Reaper

RQ-11 Raven

Wasp III BATMAV

RQ-170Sentinel



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Rapid Growth in UAS Use by USAF



USAF Need for RPA Pilots, Operators,and Ground Crews is Growing Quickly

2004 2009 2011

RQ-4 Global Hawk MQ-1 Predator MQ-9 Reaper

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Emerging Roles and New Concepts for Large and Medium Size UAVs

UAS moving beyond traditionalsurveillance and kinetic strike roles

Longer-endurance missions requirehigh-efficiency engine technologies

In-flight automated refueling will bekey for expanding UAS capabilities

May include ISR functions beyondtraditional electro-optic surveillance

LO may allow ops in contested ordenied (non-permissive) areas

Electronic warfare (EW) by stand-injamming is a possible future role

Wide-area airborne surveillance(WAAS) is increasingly important

Directed energy strike capability islikely to grow (laser and HPM)

Civil uses include border patrol and

interdiction, and humanitarian relief



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Ultra-Long Endurance Unmanned Aircraft

New unmanned aircraft systems (VULTURE)and airships (ISIS) can remain aloft for years

Delicate lightweight structures can survivelow-altitude winds if launch can be chosen

Enabled by solar cells powering lightweightbatteries or regenerative fuel cell systems

Large airships containing football field sizeradars give extreme resolution/persistence



New Multi-Spot EO/IR Sensors for UAVs

Multi-spot EO/IR cameras allow individuallysteered low frame rate spots; augment FMV

Gorgon Stare now; ARGUS-IS will allow 65spots using a 1.8 giga-pixel sensor at 15 Hz

Individually controllable spot coverage goesdirectly to ROVER terminals on ground

Autonomous Real-Time Ground UbiquitousSurveillance - Imaging System (ARGUS-IS)



UAS Automated Aerial Refueling (AAR)

Aerial refueling of UAVs from USAF tanker fleet isessential for increasing range and endurance

Requires location sensing and relative navigationto approach, hold, and move into fueling position

Precision GPS can be employed to obtain neededpositional information

Once UAV has autonomously flown into contactposition, boom operator engages as normal

Key issues include position-keeping with possibleGPS obscuration by tanker and gust/wake stability

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Flight Testing of UAS AAR Algorithms

August 2006 initial flight tests of AFRL-developedcontrol algorithms for automated aerial refueling

KC-135 with Learjet-surrogate UAS platform gavefirst “hands-off” approach to contact position

Subsequent positions and pathways flight testand four-ship CONOPS simulations successful

120 mins continuous “hands-off” station keeping

in contact position; approach from ½-mile away

12 hrs of “hands-off” formation flight with tanker

including autonomous position-holding in turns

Position-holding matched human-piloted flight



Increased Autonomy in UAS Missions

Autonomous mission optimization underdynamic circumstances is a key capability

Must address UAV platform degradation aswell as changes in operating environment

Operator only declares mission intent andconstraints; UAV finds best execution path

Vigilent Spirit is current implementation



Distributed/Cooperative Control of UAVs

Optimized scalable solution methodsfor multiple heterogeneous UAVs

Allows multiple UAVs to act as singlecoordinated unit to meet mission need

Scalability of methods is essential toallow future application to larger sets

np -hard problem; exponential growth



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Distributed/Cooperative Control of UAVs

Task coupling of multiple UAVs is key incomplex environments; e.g. urban areas

Must include variable autonomy to allowflexible operator interaction with UAVs

Allow dynamic task re-assignment while

reducing overall operator workload Demonstrated in Talisman Saber 2009



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Growing DoD Need to Improve Process for Integrating UAS in National Airspace



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Integration of UAS Operations in National,International, and Military Airspace

Authority :

Federal Aviation Authority (FAA)

Separation :

Cooperative : TCAS / ADS-BNon-Cooperative : Visual

Airfields :

Friendly and well known

International AirspaceNational Airspace Military Airspace

CollisionAvoidance ConflictAvoidance

Authority :

Int’l. Civil Aviation Org. (ICAO)

Separation :

Cooperative : TCASNon-Cooperative : Visual

Airfields :

Limited access, not well known

Authority :

Department of Defense (DoD)

Separation :

Cooperative : IFFNon-Cooperative : Radar, Visual

Airfields :

Limited, austere, security



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UAS Autonomous Collision Avoidance and Terminal Airspace Operations

Must address all aspects of UAV situationalawareness and control

Airspace deconfliction, air-ground collisionavoidance, terminal area operations

Must be immune to UAS “lost-link” cases;

“remotely-piloted” becomes “unmanned”

Surface avoidance (vehicles, obstructions)

U-270K

60K

Global Hawk

Heron 1

Predator A

50K

40K

30K

20K

10K

A l t i t u d e

1020

30Endurance (hours)

Hermes, Aerostar,Eagle Eye, FireScout, Hunter

Heron 2

Predator B



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Developing Increased Trust in Autonomy: Verification & Validation of UAS Control

Flight Control Requirements

Control Design

Control Analysis

Software Requirements

Software Design

Software Implementation

Software Test & Integration

System Requirements

System Architecture Design

System Verification & Validation

System Architecture Analysis

Systems and software V&V is amajor cost and schedule driver

High level of autonomy in UAVswill require new V&V methods

IVHM for mission survivability

Complex adaptive systems withautonomous reconfigurability

Approach infinite-state systemeven for moderate autonomy

Data/communication drop-outsand latencies make even harder

Traditional methods based onrequirements traceability fail

Extremely challenging problem;must overcome for UAS “trust”

Requires entirely new approach



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“Formal Methods” vs “Run- Time Method”

for V&V of UAS Control Systems

Formal methods for finite-state systemsbased on abstraction and model-basedchecking do not extend to such systems

Probabilistic or statistical tests do notprovide the needed levels of assurance;set of possible inputs is far too large

Classical problem of “proving that failure

will not occur” is the central challenge

Run-time approach circumvents usuallimitation by inserting monitor/checkerand simpler verifiable back-up controller

Monitor system state during run-time andcheck against acceptable limits

Switch to simpler back-up controller ifstate exceeds limits

Simple back-up controller is verifiable bytraditional finite-state methods

Run-time V&V system



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Batteries & Liquid Hydrocarbon Fuel Cells Will Be Needed to Power Small UAVs

Small UAVs need suitable power sourcefor propulsion and on-board systems

Desired endurance times (> 8 hrs) causebattery weight to exceed lift capacity; ICengine fuel efficiencies are too low

Fuel cells give lightweight power system

but must operate on logistical LHC fuel JP kerosene fuels ideal, liquid propane is

usable; need on-board fuel processor

Solid-oxide fuel cells are best to date;current record held by U. Michigan team> 9 hrs aloft with propane in small UAV



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MAVs: New Aerodynamic Regimes and Microelectromechanical Components

Micro UAVs open up new opportunitiesfor close-in sensing in urban areas

Low-speed, high-maneuverability, andhovering not suited even to small UAVs

Size and speed regime creates low-Reaerodynamic effects; fixed-wing UAVsbecome impractical as size decreases

Rotary-wing and biomimetic flapping-wing configurations are best at this size

Requires lightweight flexible structuresand unsteady aero-structural coupling



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Low Reynolds Number Flow Associated with Flapping-Wing Micro Air Vehicles

Unsteady aerodynamics w/ strong couplingto flexible structures is poorly understood

AFRL water tunnel with large pitch-plungemechanism allows groundbreaking studies

Advanced diagnostics (SPIV) combined withCFD are giving insights on effective designs

MAV aerodynamics, structures, and controlare accessible to university-scale studies



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AMASE: Air Force Research Laboratory’s

AVTAS Multi-Agent Simulation Environment

Desktop simulation environment developedat AFRL for UAV cooperative control studies

Used within AFRL to develop and optimizemultiple-UAV engagement approaches

Public-released by AFRL to universities; nolicense restrictions and no acquisition cost

Self-contained simulation environment thataccelerates iterative development/analysis

AMASE User Interface



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AMASE Can Be Used to Develop/Assess

New Collaborative Control Algorithms

Example shows comparison of control laws formission with multiple areas and no-enter zones

Heterogeneous UAVs make intuitive approachtoo complex; results show performance differs

Allows effectiveness of control algorithms tobe quantitatively assessed and compared

Enabled maturation of process algebra laws forUAVs flown in Talisman Saber 2009

AMASE modeling details are documented andpublicly available in AIAA-2009-6139

Comparison of two cooperative

UAS control systems



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Concluding Remarks

We are still at the very early stages ofUAS evolution, roughly where aircraftwere after WWI; much is changing

Developments over next decade willspan from large UAVs to MAVs as key

technologies and missions evolve: Advanced platforms and sensors

Operations in non-permissive areas

Automated aerial refueling

Coordinated control of multiple UAVs

UAS integration across airspace V&V to provide trust in autonomy

Creative approaches and technologyadvances will be needed to exploit thefull potential that UAVs can offer

exploiting unmanned aircraft systems

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