uav see & avoid employing vision sensors march 4, 2004 eric portilla northrop grumman...

HEADER / FOOTER INFORMATION (SUCH AS PRIVATE / CONFIDENTIAL)

UAV See & Avoid Employing Vision Sensors

March 4, 2004

Eric PortillaNorthrop Grumman CorporationIntegrated Systems

Aerospace Control and Guidance Systems Committee Meeting

2


See and Avoid Role in Collision Avoidance

Collision Avoidance Has Many Layers of Protection See & Avoid Functionality Is Last

Line of Defense All Preventative Measures Fail

Procedural Air Traffic Management

See & Avoid Sensors UAV Blurs Functional Boundary

Source Of Data Not Important Work With Cooperative Sensors

Procedural

CooperativeTraffic Avoidance

Air TrafficManagement

See & Avoid

3


Manned Vehicles See & Avoid Detection (See)

Cooperative Situational Awareness Transponder Communication Position Broadcasts Ground Radar Uplink

Pilot Eyes Verification of Situational Data Non-Cooperative Vehicles

Avoidance Collision Avoidance Algorithms Pilot Intangibles

Experience Reasoning Data Fusion and Evaluation

4


Sensor Requirements Driven By Avoidance

Provide Sufficient Information Tracking

Associate Current to Previous Data ID Data Correlation

Path Projection Determine Threat Estimate Time To Collision

Adequate Detection Range Time To Perform A Maneuver

5


TCAS II Surveillance Leverage Aircraft Transponders

Interrogates on 1030 MHz Mode A/C All Calls & Mode S

Replies On 1090 MHz Altitude ICAO Address (Mode S Only)

Directional Antenna Relative Bearing (~ +/- 5°)

Response Time Used To Calculate Range

Certified and Mandated Required By FAA

>30 Passengers >33,000 lbs Gross Take-Off Weight

6


Automatic Dependent Surveillance – Broadcast (ADS-B) Broadcasts

Own GPS Position, Altitude Accurate

ID Intent

Range (>100 nmiles) Rebroadcasts Extend Range

Three Datalinks Universal Access Transceiver Mode-S VDL – VHF (Asia and Europe Only)

Requires Compatible Equipment Not Mandated Currently Not Widely Used

7


Class A Airspace

TransponderEquippedAircraft


100nmi


Non-TransponderEquippedAircraft


ADS-B Conceptual Diagram

8


Traffic Information System–Broadcast (TIS-B) Ground-Based System

Integrates Primary Radar (No Altitude) Transponder Returns

Broadcasts Information ADS-B Format

“Fills The Gap” For Situational Traffic Awareness Provides Non-Cooperative Radar Data

Requires Ground Infrastructure Currently Only Pockets of Coverage

Alaska Capstone Ohio Valley Prescott, Az

Currently Only Transponder Data

9


TIS-B Conceptual Diagram

Class A Airspace



100nmi




Rebroadcast Equipment

Rebroadcast Equipment

PrimaryRadar

PrimaryRadar

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Radar Gimbaled or Electronically

Scanned Configured To Meet Field

Of Regard Requirements Detected Threat Data

Elevation Angle Bearing Angle Range

Good Range (8 - 10 nm for GA)

All Weather No ID

Requires Correlation Algorithm

11


Vision Sensors

Multiple Fixed Staring Sensors Configured To Meet

Field Of Regard Requirements

On-board Image Processing for Moving Target Detection

Detected Threat Data Elevation Angle Bearing Angle Image Size

Does Not Provide Range

12


Detection Techniques

Detection Own Vehicle Motion

Causes Image Movement Creates An Optical

Flow Field Intruder Aircraft Do Not

Move With The Background Flow Field

Discontinuity

9

SBIR Phase II/IIE Technical Approach Demonstration

Processed Video(Slow Motion)

• Aircraft motion causes image of background to move across detector

• Missile trajectories do not move with the background

• Optical flow field discontinuity results

• “Discontinuity filter” identifies missile location

13


See & Avoid Sensing Architecture

Sensor Data Management

and Correlation• Establish

Sensor Data Tracks

• Correlate Sensor Data to Intruders

Radars

VisionSensors

KF-based Optimal Tracking

Filter• One Filter for

Each Intruder• FDI

– Sensor Errors

– Sensor Correlation Errors

AutonomousAvoidance

Subject to Ownship Performance Limitations

• Reliable and Fault-Tolerant Detect, See, and Avoid (DSA) Capability Through Multiple Dissimilar Sensors Integration

ADS-BTIS-B

TCAS

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Combined Sensor Configuration Benefits Realized

Protection Against All Vehicles Coop & Non-Coop

Multiple Dissimilar Sensors Redundancy Fault Tolerance Reliability

Concept of Operations: Fuse Multi-Sensor Data Processing Track Reports:

TCAS, ADS-B & TIS-B Can Be Correlated On-Board Provide Same ICAO Address ID’s

Vision And Radar Require Track Correlation Sensor Level? System Level?

15


Sensor Protection Volumes

TCAS/ADS-B/TIS-B: Cooperative, emission All aspect All weather

Radar: Non-cooperative, emission All weather

Vision: Non-cooperative, no

emission

16


Fusion Architectures: “Pre-Detection Fusion”

Pros: Theoretically Optimal Topology Allows Optimal Associations More Accurate Global Tracks

Cons: Computationally Prohibitive With Many Targets (NP Hard) High Integration Risk (Sensors with Different Sample Rates) Susceptible to Sensor Degradation; Difficult to Detect and

Isolate Faults

Sensor 1

Sensor 2

Sensor n

Centralized

Measurement

Association

and Tracking

Local

Measurements

Local

Measurements

Global

Tracks

Local

Measurements

17


Fusion Architectures: “Post-Detection Fusion”

Pros: Reduced Complexity for Local Multi-Target Trackers Improved Modularity & Easier Integration Improved Sensor Fault Detection & Isolation Capability

Cons: Less Accurate Data Associations and Global Tracks

Sensor 1

Sensor 2

Sensor n

Tra

ckA

sso

ciat

ion

Local

Measurements

Tra

ck

Fu

sio

n

Multi-TargetTracker

Local

Measurements

Multi-TargetTracker

Local

Measurements

Multi-TargetTracker

Local

Tracks

Local

Tracks

Local

Tracks

Local

Tracks

Global

Tracks

Correlated

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Summary

Equivalent Level Of Safety Detect, Recognize, Decide, and Maneuver Perform at Least as Well as if a Human Pilot Was

Onboard In Reality Much Higher

Vision Sensors Easily Out Perform Pilot Eyes Data Processing Remains The Key!

Multiple Sensors Create Robustness But Add Complexity Data Fusion

Target Duplication False Targets Sensor Transitions

uav see & avoid employing vision sensors march 4, 2004 eric portilla northrop grumman...

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