SOARS

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SOARS

Matt EdwardsArseny DolgovJohn Shelton

Johnny JannettoGalina Dvorkina

Nick DriverEric Kohut

Kevin Eberhart

Self Organizing Aerial Reconnaissance System

Critical Design ReviewASEN 4018 Senior Projects

11/15/06

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Presentation Outline• Overview and Objectives• System Architecture

• Objectives• Requirements• System Design• Expected Performance

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Project Overview• Objective: Design, build and test an autonomous aerial system (UAS)

capable of imaging multiple targets within a 1km circle as quickly as possible with 99% probability of object detection (according to Johnson criteria).

• AFRL COUNTER Project• Optimal imaging altitude <100m for a small aerial vehicle• Minimize risk to larger master vehicle

31. AFRL COUNTER Project. Used with permission.

hmax = 70 m

Truck

Target

(X,Y,Z)

Slave

Master

Ground Station

GPS Coordinates, Heading

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Test Scenario

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Requirements Overview• Image at least 3 targets, satisfy Johnson Criteria

• Time: <8 minutes• Flying distance: >4 km

• Slave UAV >1km radius of operation in relation to stationary (assumed) Master vehicle

• New critical requirement:• Image lag < 2 seconds from slave to ground-station

• Targets given by GPS location and heading from ground station

• Slave UAV• Max weight: 1.5kg• Maximum width for below-wing mounting:

120 cm

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Requirements Detail

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Slave Vehicle

Communications

Power

Control

Imaging

Range > 4km

Bandwidth >250kbps

Resolution >600lines

Working Distance <90m

30° < FOV <60°

Heading within 30°Rate < 12°/s

Roll within 30° Rate < 115 °/s

Pitch within 30° Rate < 12°/s

Position accurate to 10m

· Telemetry/Images Sent over >1km to Master· Delay to receiving image: <2sec· >3 Targets imaged, satisfying Johnson Crit.· < 10% Image Blur· Travel at least 4km in 8 minutes· Autonomous navigation to GPS coord, heading· Deployable from SIG Master vehicle

<2 seconds image delay

Speed > 30km/h

Master Vehicle

· Relay 640x480 images in <2 sec· RF Link endurance >20min· >2km range to Ground Station· Manually Piloted RC· Must be able to carry Micropilot module

Power

Must fit inside 5x10x5 cm box

Range: >2km

> 20 min operating time for avionics/comm subsystem

Data relay, >250kbps< 2 sec delay

Avionics

Ground Station

Communications

Graphical User Interface

Control Software

· Slave telemetry update rate: 1Hz· Identify image w/ location and timestamp· Send target (GPS, heading) commands to

slave via master· Range to Master: >2km· Receive 640x480 images in <2 sec

GS-Master Handshaking

Receive Data at 1Hz

Range >2km

Bandwidth >250kbps

GPS XY InputHeading Input

Display 640x480 image

Display slave telemetry: position, velocity

Ensure slave receives command

Slave loiters above preprogrammed target, acquiring images.

Fully loaded take-off and deployment of two slaves. Advanced flock management.

Slave flies to and loiters above any target specified by GS and sends back pictures.

As below, but coordinates and pictures relayed through master vehicle.

Demonstrate “theoretical” slave deployment capability w/ designed

mechanism.

Demonstrate ground-deployment of slave.

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Deliverables

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• Selection of slave vehicle• GS to Master to Slave RF link

• Image reception• Target specification• Demonstrate <2 sec image delay

• Slave telemetry (GPS position, altitude, heading, speed)

• 3 Images taken with correct position, attitude (Johnson criteria)

• Autonomous navigation• Deployment feasibility

Future COUNTER Mission

Target System

System Architecture: Slave

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PCB Design& Fab

•Slave requires custom interface and power board to house camera and send data to CU Autopilot.•Custom autopilot and controls software will be developed to meet target imaging requirements.

SLAVE VEHICLE

CU Autopilot

PIC MicrocontrollerControl Software

1000mAhLiPo Battery

ESC

GPS

Rate Gyro

Servos

Motor

Altimeter

TO MASTER @ 2.4Ghz

Short-Range ZigBee Transceiver, 250kbps OTR

Send BufReceive Buf

Daughter Board

CMOS JPEGCamera

3.3 V Regulator

Level Shift

115kbps Asynch

Power Subsystem

Processing Element

Communications

System Architecture: Master

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PCB Design& Fab

•Master houses two COTS radios•1 long-range point-to-point (for communication with ground-station)•1 short-range multipoint (for communicating with multiple networked slaves)

•CU autopilot provides data for verification, maintains master UAV loiter•Custom microcontroller software handles command dispatch and data/telemetry

Power Subsystem

Processing Element

Communications

MASTER VEHICLE

Long Range Radio Modem, 800kbps OTR

1000mAhLiPo Battery

3.3V Regulator

Servos

Motor

Microcontroller – PIC18F8722

Short-Range ZigBee Transceiver, 250kbps OTR

Send Buf Receive Buf Send BufReceive Buf

TO SLAVES @ 2.4GhzTO GROUND STATION @ 2.4 Ghz

5.0 V Regulator

Control Software

UART0

Send Buf

Receive Buf

Level Shift

CU Autopilot

PIC MicrocontrollerStock Software

UART0

Receive Buf

Send Buf

800kbps Asynch

250kbps Asynch

ESC

GS Board

Long Range Radio Modem, 800kbps OTR

USB Power

Microcontroller – PIC18F8722

Send Buf Receive Buf

TO MASTER @ 2.4Ghz

5.0 V Regulator

Control Software

UART0

Send Buf

Receive Buf

800kbps Asynch

UART1

Receive Buf

Send Buf

250kbps Serial to USB Converter

System Architecture: Ground Station

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PCB Design& Fab

Computer

Power Subsystem

Processing Element

Communications

Target Location Input

Heading Input

PC Interface

•Ground station houses 1 long-range radio for sending commands to master•Custom microcontroller and software interface to PC graphical interface

•GUI allows user to enter target location, issue commands•Image display

Slave Component Layout

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2.4GHz RF Antenna

GPS Antenna

ZigBee Radio

Rate Gyro

LiPo Battery Pack

ESC

RC Receiver

Camera Mount Under Wing

Master & Slave Mounting

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Autopilot Control Method

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• Lyapunov vector field used for navigating to designated target at desired GPS location and heading.

• Custom autopilot code will use roll rate-gyro and GPS for heading control• Altitude hold to be implemented with pressure altimeter. Elevators and thrust

used for altitude control.

Software Design

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Slave Receive Interrupt Service Routine

GS Receive Interrupt Service Routine

Power-OnInit UART0Init UART1

Baud RateParity

Data Bits

Setup SR ZigBeeAddress

Packet SizePower, etc

Setup LR ModemAddress

Packet SizePower, etc

Enable UART0/UART1 Interrupt

IDLE

UART0 Receive (GS)

UART1 Receive (Slave)

Parse out packetSlave ID

Target Spec: XYZ, H

Ready to send?

Transfer Data to UART0

YES

Data Packet (imagery, etc)

Perform computation/make

decision??

Ready to send?

Transfer Data to UART1

YES

• Interrupt-driven operation ensuresthat both radios are serviced bymaster vehicle

• Master waits for input fromradios, receives commands

• Retransmits commands to slaves

• Sends back images,telemetry

Expected Performance• Imaging

• Aircraft

• Communications

• Autopilot

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Imaging Performance• 640x480 JPEG compression camera

• 6 lines of resolution within target (meets Johnson criteria) at 100m range• 60° FOV leaves >30° margin in pitch, roll and yaw

• Plots show that maximum perpendicular velocity during approach < 20m/s.

• At this speed, camera blur is well below 10%

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-100 -80 -60 -40 -20 0 20 40 60 80 100-30

-20

-10

0

10

20

30Plot of Velocity

Range to Target (m)

Vel

ocity

(m

/s)

Perpendicular Velocity

Tangential Velocity

about 10 m/s

about 20 m/s

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 150

100

150

200

250

300

Blur Factor

Max

imum

Tan

gent

ial V

eloc

ity (m

/s)

t = 0.007

t = 0.009

t = 0.011

t = 0.013

Communications Performance• Communications subsystem must ensure <2 seconds image propagation

delay• Camera outputs 16kbyte JPEG images• Slowest link in system must be >115kbps

• Current system limited by image retrieval speed from camera• 115kbps bottleneck in camera interface• No other camera available with built-in JPEG compression• Most cameras output RAW format in 8-bit parallel, image size too big (>400kbytes)

• Communications system has large margin (250kbps minimum data rate) to leave room for protocol overhead, errors and dropped packets

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Image Path Delay < 2 seconds

Ground Station Master Vehicle Slave Vehicle

800kbps 250kbps

Camera Module

MCU

115kpbs

Radio

500kpbs

MCU

Radio 1Radio 1

500kpbs500kpbs

Graphical User Interface

MCU

250kpbs

Radio

500kpbs

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Autopilot Performance•Use of custom Lyapunov field for pointing and direction control (simulation below)•Vector field center can be adjusted to switch to different targets•Simulation results show that particle traveling at 20m/s is guided to within 30° of target heading on approach, and particle passes directly overhead of target.

-100 -50 0 50 100 150 200 250 300 350 400-500

-400

-300

-200

-100

0

100

200

x position

y po

sitio

n

projected path of particle in slave vector field starting (0 -300)