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MaritimeSurveillance
borderpatrol
CommercialJet
StratosphericTelecommunications
Airship
High-AltitudeImagery
Tactical LawEnforcement
EnvironmentalSensing
Media/TrafficReporting
Velocity Obstacle (absolute)Translations of the relative
VO along ��’
Every velocity vector ofUAV A lying inside VOAB arebound to collide with UAV B
Shadowof UAV BVelocity
Velocity Obstacle (relative)A triangle limited by the two tangent
line of UAV B avoidance spherefrom UAV A
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AvoidanceSphere
UAV AUAV B
Distance
RelativeVelocity
OriginalFlight Path
Inside cooperative sphereAvoidance maneuvers arebased on cooperative rules,while still considering theoriginal flight path
Inside non-cooperative sphereAvoidance maneuvers are strictlyconducted to escape as soon aspossible to safety
Protected Zone
Non-cooperativeSphere
CooperativeSphereTraffic
WarningSphere
1.1 span40 sec25 sec
1.5 sec
1% 0.001% 0% 0.003% 0% 0.005% 0% 0.007% 0%2.5% 4% 1%
Collision Probabilitiesvia MonteCarlo Simulationin Area 1 km x 1 km
3 Agents 4 Agents 5 Agents2 Agents
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BackgroundLike any other technology which first started at military bases,UAVs will start affecting civilian live in just a couple years fromnow. Currently there are already industries that provides lowend UAVs technologies for various non-military purpose, mostof them are remote-controlled toys. However, with theincreasingly faster advancement of technology, these UAVswill soon be more than toys. Department like Police and FireBrigade began to count the possibility of deploying UAVs forspecific missions, frequently, and in a non-secluded area.Previous researches give several predictions on what willbecome of UAVs in the future that affects civilians life.
Civilian purposes UAVs will of course required to fly in a non-secluded area, or even in some populated area. This situationcan be hazardous, for the (1) UAV itself, (2) other (civilians)UAVs, (3) the manned-flight, and most importantly, (4) peoplein the flight area. Therefore, in order to be used widely in anon-secluded area, or also known as the National AirspaceSystem (NAS), UAVs are required to have an well standardizedCollision Avoidance System, which should be able todemonstrate an equivalent level of safety.
Thus, the research aims to define and investigate theautonomous collision avoidance system (ACAS) forUAVs, in context of integrating UAVs into the NationalAirspace System.
Cooperative and Non-cooperative Avoidance
The avoidance structure for UAVs is set to have two layer ofsafety. These are the Cooperative, and the Non-cooperativeavoidance layer. The first one use a common rules ofavoidance which expected to be followed by every UAVinvolved. The later is avoidance purely by trheating the otheUAV as a rogue obstacle/intruder
Avoidance Algorithm: Velocity Obstacle Method
A method called the Velocity Obstacle (VO) Method , orsometime the Forbidden Zone Beam Method, is used to defineavoidance criteria. The VO-method was chosen due to itssimple implementation and geometrically understandablecompare to others. To be suitable for the implementation inUAVs ACAS, however, several modifications were made,producing a new branch of the Velocity Obstacle Method,which be referred as the Selective Velocity Obstacle Method(SVO).
SVO will also acomodate rules that form the cooperativeautonomous collision avoidance system for UAVs (Co-ACAS)
Rules of Cooperative Avoidance
Adapted form the Rules of Air in the manned-flight, the rulesfor are:
1. On encounter, The one on the right handhave the right of way
2. On encounter, both UAV should move to theright side
3. On , the one that are about to be takenover have the right of way
4. Avoidance should not go over or under, or in front ofother UAV that have right of way
Having the Right of way means the UAV could keep goingmaintaining its original flight path, while expecting the otherUAV will conduct the avoidance, hence resolve the conflict. Ifnot resolved, then the non-cooperative avoidance should beconducted.
Converging
Head-on
Taking Over
SimulationsUsing the VO-method and cooperative avoidance rules, a 2-Dimensional simulations were conducted for all converging,head-on and taking over encounters. The simulation weredone using Matlab program that was developed throughoutthis research, which are able to simulate up to 5 agents of UAVin various conditions and configurations.
Collision Probabilities (Monte Carlo Simulations)
To predict the collision probabilities from various initialconditions and configurations, several Monte Carlosimulations were set. Using 1000000 number of samples, andrandomly distributed positions (Cartesian), airspeed, andheadings.
Three set of Monte Carlo Simulation were conducted, i.e, forscenario (1) without any ACAS implemented, (2) with ACASimplemented but no rules (non-cooperative), and (3) with Co-ACAS implemented.
The result were in favor of the Co-ACAS, resulting zerocollisions in all samples.
1. SenseDepends on sensorscapabilities, obstacle
type, and environmentalconditions
2. DetectCalculate a few steps aheadthe probabilities of collisions,depends on UAVs sizes andVelocities, and Headings
3. AvoidanceChange flight pathto ensure safety.Depends on UAVsmaneuverabilityand performance.
UAV AWith Sense, Detect,
and Avoid System
UAV BThe Obstacle
sensing range
Non-Cooperative Avoidance
• just avoid as fast as possible, using everydegree of freedom (thus, )
• Avoidance could be conductedsphere, or
, whichever comes first
• Avoidance conducted to to theprotective sphere
• Sensors areNoise are expected
Several Sensor use in the research are new and small withvery limited performance to be light for UAVs. This create anew challenge of avoidance: Sense and Avoid, withoutDetection
No Rules,3D
at the edge of the 1.5sas soon as obstacle sensed and/or
conflict detected
avoid collisions
on-boards, high frequency, and shortranges.
and its still continuing
What Next?
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Real experiment on UAVs Cooperative Avoidance usingwith simulated ADS-B
Setting up standard requirements for UAV to integratewith the National Airspace System
Setting up standard sensor requiremnets for specific UAVcategories
Hybrid Modeling on avoidance and control
Simulation for Non-cooperative avoidance and escapemaneuver
Publications- Y.I. Jenie, E. van Kampen, B. Remes (2013) “Cooperative Autonomous Collision Avoidance System for Unmanned Aerial Vehicles”, CEAS EuroGNC 2013 conference, Delft (To be Presented)- Y.I. Jenie, E. van Kampen, C.C. de Visser, Q.P. Chu (2013) “Selective Velocity Obstacle Method for Cooperative Autonomous Collision Avoidance System for UAVs”, AIAA Guidance,
Navigation and Control Conference, Boston Massachusetts (Abstract Submitted)- Y.I. Jenie, (2013) “Hybrid Modeling of Velocity Obstacle Method in Autonomous Collision Avoidance System for UAVs “, AIAA Modeling and
Simulation Technology Conference,E. van Kampen, C.C. de Visser, Q.P. Chu
Boston Massachusetts (Abstract Submitted)
Predictions on what will become of UAVs in the future that affectscivilians life
Cooperative and Non-Cooperative Avoidance structure definitions From top, simulations of (1) Converging encounter, (2) Head-on Encouinter(3) Taking Over, and (4) Eight symmetric converging
Definitions of Sense-Detect and Avoid. Several sensors are so light andsimple that cannot be used to conduct detection
Velocity Obstacle Method graphical explanations
Monte Carlo simulation result on collision probabilities of cooperativeavoidance for UAV, Number of Samples : 1000000
Autonomous collision
avoidance system for UAVsTowards integration with National Airspace System
PhD Candidate : Yazdi Ibrahim JenieDepartment: C&OSection: Control and SimulationsSupervisor: E. van KampenPromoter: M. MulderStart date : 06-06-2011Funding: IDB Merit for High TechnologyCooperations: -
Aero
space
Engin
eering
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