SOARS

1
SOARS
Self Organizing Aerial Reconnaissance System

• Arseny Dolgov
• Nick Driver
• Galina Dvorkina
• Kevin Eberhart
• Matt Edwards
• Johnny Jannetto
• Eric Kohut
• John Shelton

Critical Design Review ASEN 4018 Senior
Projects 11/15/06 Professor Dale
Lawrence Professor James Maslanik
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Presentation Outline

• Overview and Objectives
• System Architecture
• Critical Test Results
• Design Elements
• Electrical Design
• Software Design
• Integration and Verification
• Project Plan Management
• Appendix

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3
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 lt100m for a small aerial
  vehicle
• Minimize risk to larger master vehicle

Master
GPS Coordinates, Heading
Ground Station
1. AFRL COUNTER Project. Used with permission.
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Test Scenario
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Requirements Overview

• Image at least 3 targets, satisfy Johnson
  Criteria
• Time lt8 minutes
• Flying distance gt4 km
• Slave UAV gt1km radius of operation in relation to
  stationary (assumed) Master vehicle
• Targets given by GPS location and heading from
  ground station
• Slave UAV
• Max weight 1.5kg
• Maximum width for below-wing mounting 120 cm
• New critical requirement Image lag lt 2 seconds
  from slave to ground-station
• Motivation Operator must react quickly if a
  threat is detected
• Camera image retrieval takes at least 1 second

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Deliverables
Future COUNTER Mission
Target System

• Selection of slave vehicle
• GS to Master to Slave RF link
• Image reception
• Target specification
• Demonstrate lt2 sec image delay
• Slave telemetry (GPS position, altitude,
  heading, speed)
• 3 Images taken with correct position, attitude
  (Johnson criteria)
• Autonomous navigation
• Deployment feasibility

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Requirements Summary
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System Architecture Slave

• 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.

Design and Fabricate PCB (Printed Circuit Board)
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System Architecture Master

• 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

Design and Fabricate PCB
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System Architecture Ground Station

• Ground station houses 1 long-range radio for
  sending commands to master
• Laptop uses software to interface directly to
  radio no need for MCU.
• MATLAB interfaces with/controls Aerocomm
  development board via serial link
• MATLAB GUI allows user to enter target location,
  issue commands
• Image and telemetry display

Target GPS XYZ Heading ?
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Slave Component Layout
GPS Antenna
Rate Gyro
ZigBee Radio
RC Receiver
Ducted Fan
2.4GHz RF Antenna
ESC
Camera Mount Under Wing
LiPo Battery Pack
Elevon Control Surfaces
Custom Canopy
Winglet Stabilizers
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Complete System Assembly
Comm Board Battery Pack
SIG Rascal 110 ARF
Slave Vehicle
Mounting Pylon
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Expected Performance

• Autopilot
• Imaging
• Communications
• Propulsion Power

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Autopilot Performance

• Vector field guides slave UAV to arbitrary target
  and heading
• Total distance traveled for three targets 7 km
• Minimum speed for mission length lt8 min 33 mph

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Trajectory Control
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Imaging Performance

• Quick Imaging Geometry Facts
• Max Imaging Range 80 m
• (actual 65 m)
• Camera can see 19,000 m2
• Airplane is in imaging window
• for 2.7 s

Tangential Velocity Required lt60 m/s Actual 15
m/s
Cruise velocity 17 m/s
Pitch Rate Required lt0.4 rad/s Actual 0.2 rad/s
Depression Angle 45 deg
Radial Velocity Required lt80 m/s Actual 8 m/s
Imaging Altitude 45 m
Ground distance to target 45 m
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Communications Performance

• Communications subsystem must ensure lt2 seconds
  image propagation delay
• Camera outputs 16kbyte JPEG images
• Slowest link in system must be gt115kbps
• 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 (gt400kbytes)
• Communications system has large margin (250kbps
  minimum data rate) to leave room for protocol
  overhead, errors and dropped packets

Actual Path Delay 1.4 s
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Critical Pre-CDR Test Results
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Critical Testing Camera Jitter

• Image blur/distortion due to engine jitter and
  vibrations is unpredictable and must be tested
• High-frequency (kHz range) vibrations cause CCD
  to move while rows of pixels are read resulting
  image gets shifted between row reads
• Engine must be stopped during imaging

Blur Shutter too slow
Engine OFF
Rolling Shutter Distortion
Engine ON, 80 Throttle
Engine ON, Camera Rotated 90
Fast Global Shutter
1 Electronic Shuttering for High-Speed CMOS. -
Dalsa Corp.
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Critical Testing Camera Resolution

• JPEG compression might cause loss of effective
  camera resolution must be verified
  experimentally
• Resolution test pattern used to verify actual
  resolution
• Test indicates no noticeable loss in camera
  resolution
• Camera meets design-to specification of gt300 lines

Lines become indistinguishable at approximately
400 lines of resolution marker
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Critical Testing Power System

• Wingless ducted fan tested at 56mph
  (manufacturers optimal speed) in the wind tunnel
  to simulated actual load conditions
• Measured battery discharge voltage and current
• ElectriFly 3 Li-Polymer Cells
• 11.1 Volts
• 910 mAhr
• Ran for 5.5 minutes

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Electrical Design
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Electrical Design Communications

• Master to Ground Aerocomm AC1524 Modem
• Master to Slave X-Bee PRO ZigBee Radio
• Multiple selectable channels on each radio to
  prevent interference

Required 250 kbps Actual 800 kbps
Required 250 kbps Actual 250 kbps
Required 2 km Actual 3.2 km
Required 1 km Actual 1.6 km
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Electrical Design Power

• Slave UAV power requirements driven by propulsion
  system (avionics consume lt2 compared to motor)
• Master UAV requirements driven by high-power RF
  transceivers

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Electrical Design Power

• Slave avionics must operate for gt8 minutes
• Battery 3-Cell 1800mAh LiPo
• Master avionics must operate for gt30 minutes
• Battery 3-Cell 1000mAh LiPo
• Master UAV power supply design-to
• Input Voltage 7.5V-11.1V due to LiPo discharge
  variation
• Outputs
• 1A _at_ 5.0V for Long-Range transmitter
• 500mA _at_ 3.3V for Short-Range Zig-Bee radio

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Master UAV Comm Board Layout

• Minimize trace length for high-frequency/data
  rate signals
• Power supply decoupling close to MCU pins to
  minimize noise from RF
• Bottom-layer ground plane to reduce noise

Long Range Radio Modem
PIC Microcontroller
Power Supplies
ZigBee short-range Radio
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Electrical Design Slave UAV Daughter Board

• Slave daughter board connects to main autopilot
  board
• Provides camera connection and power (from main
  LiPo battery)
• Provides SPI-to-Asynchronous bridge from MCU to
  Camera
• Translates voltage signals between 5.0V and 3.3V

Camera Header
Level Shifter
Power Supply
SPI Header
Crystal
SPI Bridge Chip
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Software Design
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Software Design

• Design-to
• Slave
• Control algorithm must ensure proper entry into
  imaging cone
• Perform imaging within allowable window of
  opportunity
• 250kbps image uplink rate
• Update X,Y,Z, heading, velocity at 1Hz
• Master
• 250kbps data throughput
• Manage at least 2 slaves
• lt 2 seconds image data lag
• Ground Station
• Allow Lat/Long/Heading target designation
• Image display
• Telemetry display update at 1Hz

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Software Slave

• Software performs major function of
• Hardware Configuration
• Control Implementation
• Imaging Control/Transmission
• Telemetry Transmission
• Servo and Peripheral communications handled via
  interrupt service routine
• Major additions are ability to receive ground
  commands in flight and imaging system

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Slave Imaging Software

• Compressed image sent as packets (64-512 bytes)
• Image will be taken with 6 byte configuration
  information
• Location information (Lat, Long and Altitude)
  will be attached to image transmission

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Slave Received Command Handling

• The ID is one byte of data specifying what the
  MCU should do with the following data.
• Two main options
• Next Target
• Emergency Mode
• Manual Control
• Turn off Engine

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Software Design Master

• Master vehicle acts as client to ground station
  and as server to slaves
• Ground station initializes master service
  requests
• Master initializes slave service requests
• Get image
• Get telemetry
• Download targets
• Chosen Network Topology
• Ground to Master Point-to-Point
• Master to Slave(s) Point-to-Multipoint

2.4Ghz Zig-Bee
2.4Ghz Radio Modem
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Master Software Design

• Interrupt-driven operation ensuresthat both
  radios are serviced bymaster vehicle
• Master waits in idle most of the time
• Ground issues data request
• Interrupt occurs from serial data being received
• Master accumulates packet
• Performs decision
• Issues commands and datarequests to slaves
• Slave response causes interrupt
• Cycle repeated

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Software Data Transmission Model

• Need to optimize packet size to meet lt 2 sec
  image delay requirement
• Zig-Bee data frames have at least 120bits
  overhead

Packet too small Overhead Dominates
Packet too big Wasted Idle Time
Optimal Packet Size Delay Approaches 115kbps
limit
Total Image Delay Time
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Software Packet Length Optimization

• Transmission time does not meet requirement for
  very short or very long packets.
• Optimal packet size 50bytes

Maximum Zig-Bee Packet Size
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Software Ground Station

• Ground station runs MATLAB GUI which controls LR
  radio
• GUI allows user to enter target information,
  visualize slave telemetry and take pictures

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Integration Testing
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Systems Integration and Validation

• Integration and Testing Progression
• Level 1 Isolated Component Testing
• Performance verification of individual components
• Level 2 Subsystems Integration and Testing
• Aircraft, Control System (slave vehicle),
  Imaging, Communications
• Level 3 Systems Integration and Testing
• Test systems functionality

Subsystems Integration Integrate isolated
components into relevant subsystems
Systems Integration Integrate individual
subsystems into complete system
Integrated System Validation Validate complete
integrated system performance
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Level 1 Component Testing

• Aircraft Communications
• Slave avionics and propulsion test Autopilot
  (Zig-bee) transceiver test
• Range and battery discharge verification Master
  communications link
• Long period axial oscillation frequency Ground
  station communications link
• Flight test (GPS speed/altitude verification)
  Verify GUI (display slave altitude,
• Sig Rascal performance verification speed,
  current target image)
• (GPS speed/altitude verification)
• Autopilot Imaging
• Particle vector field simulation High frequency
  motor vibration
• Simulink vector field simulation with Stryker
  Camera resolution determination
• Simulink vector field simulation with
  Miglet Rotational blur (spinning table)
• Flight test Miglet (autonomous control) Camera
  data output rate
• JPEG compression error

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Level 2 Subsystems Testing

• Aircraft Communications
• Slave controllability Verify air-to-air
  air-to-ground comm.
• - RC from ground Verify transceiver ranges
• Master flight capability with slaves
  attached Quantify bit error in data transmission
• Slave deployment from master (simulated)
  -Ground/master, master/slave
• Determine transmission time between
• ground and master, master and slave
• Autopilot Imaging
• Generate target vector field for GPS coord.
  Take image per autopilot instruction
• sent from external comm. link Compress image
  to JPEG
• Command elevon servos to execute flight path
  Pass image to slave transceiver
• Instruct camera to take image
• Receive images from camera, tag picture data
• with telemetry and pass to comm. link

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Level 3 Integrated System Validation

• Flow Up Integrated System Testing
• Ground/ Master
• Ground station to master comm. link
• Ground station sends GPS coordinate to master/
  master receives GPS coordinate
• Master to ground station comm.
• Master sends picture and telemetry data to ground
  station and
• Master/Slave
• Master sends GPS coordinate and is received by
  slave
• Slave sends picture and telemetry data to master
• Slave/Autopilot
• GPS coordinate received by autopilot (Zigbee)
• Autopilot generates flight path and target vector
  fields
• Autopilot communicates with elevons and ESC to
  actively control slave to follow flight path
• Autopilot/Camera

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Level 4 System Requirements Verification

• Aircraft
• 3 targets imaged in under 8 minutes from
  acquisition of first GPS coordinate
• 99 probability of detection (Johnson Criteria)
• Communications
• Image and telemetry data received by GUI within
  2 sec of time captured
• Autopilot
• 3 target locations navigated to and over flown
  with 99 probability of
• detection (Johnson Criteria)
• lt 15 degree heading error at time of imaging
• lt /- 6 m deviation from intended altitude
• lt /- 5 m/s derivation from intended flight speed
  at time of imaging
• Imaging
• Image 3 targets each with 99 probability of
  detection (Johnson Criteria)
• Images have sufficient resolution that a human
  can discern 1 x 0.5 x 1.5m object

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Systems Integration Flow Chart
Level 1 Component Testing Level 2
Subsystems Integration Level 3 Systems
Integration Level 4 System verification

Time
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Project Plan Management
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Project Management Overview

• Organizational Chart
• Work Breakdown Structure
• Critical Path Elements
• Budget Predictions/Expenditure

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Organization
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Work Breakdown Structure
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Critical Path Elements

• Defined as elements with highest unknown time
  requirement and risk which are heavily depended
  on elsewhere in the project.
• Imaging Software/Interface
• PCB Verification
• Control Software/Algorithms
• Communications Software

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Budget Analysis
Category Name/Item Description Unit Price () Quantity Total Cost Purchased Amount ()
Controls Microcontroller Unit 20.00 3 60.00    
  GPS (Units) 75.00 2 150.00    
  Rate Gyros 50.00 3 150.00    
  Radio Development 120.00 1 120.00    
  Radios 35.00 2 70.00    
  Receiver 60.00 3 180.00    
  Autopilot 500.00 1 500.00    
  PCB Manufacturing 100.00 3 300.00    
Vehicles SIG Rascal 399.99 1 399.99    
  Motor 40.00 1 40.00    
  Slave Plane 150.00 3 450.00 3-Nov-06 99.99
  Glue 8.00 1 8.00 3-Nov-06 7.99
  6 Channel Radio 180.00 1 180.00 3-Nov-06 34.99
  Battery 60.00 3 180.00 3-Nov-06 39.99
  Battery Charger 100.00 1 100.00 3-Nov-06 36.48
  Electronic Speed Control 85.00 3 255.00    
  Servo 15.00 10 150.00 3-Nov-06 159.99
  Servo Extension Wires 5.00 1 5.00 3-Nov-06 4.29
Power Slave Motor 40.00 3 120.00    
  Speed Control 40.00 1 40.00    
  Battery Charger 50.00 1 50.00    
  Voltage Regulators 50.00 3 150.00    
Communications Modules 199.95 2 399.90    
Imaging Camera 50.00 3 150.00    
  Evaluation Board 50.00 3 150.00 5-Nov-06 55.80
Sub-Total Sub-Total Sub-Total Sub-Total 4,357.89 Total Spent 439.52
TOTAL with 25 Margin TOTAL with 25 Margin TOTAL with 25 Margin TOTAL with 25 Margin 5,810.52  Total Left   5,480.48

• Total Available
• 5,900.00
• Funding
• Senior Project
• Funds 4000
• EEF 1900

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Appendix
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Electrical Design Communications

• Network topology trades
• Server-client point-to-point direction connection
  network
• Suitable for high-data rate
• Minimal protocol and handshaking overhead
• Long ranges possible
• Simple to design, robust
• Minimal required CPU intervention
• Server to multiple-client point-to-multipoint
  connection network
• Suitable for medium data rates
• Lots of protocol and handshaking overhead
• Short-range
• More difficult to design
• Allows for more complex networks with multiple
  clients

RADIO MODEM
ZIG-BEE
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Testing Plan

• Testing and Verification Tree
• Requirements Verification Breakdown
• Order of Testing
• Component Verification
• Major System Test Procedures

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Testing and Verification Tree
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Master Vehicle Requirement Verification
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Master Vehicle Requirement Verification
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Ground Station Requirement Verification
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Testing Progression
Component Level Testing
Miglet Initial Flight Testing
Sub System Level Testing
Autopilot Testing
Software And Interface Testing
System Level Testing
Communications System Test
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Major Systems

• Ground Station System Test
• Goal To verify proper operation of the User
  Interface and display software
• Master Vehicle System Test
• Goal To verify proper operation of the Master
  Vehicles communications system and handshaking
  ability in conjunction with the Ground Station
• Slave Vehicle System Test
• Goal To verify proper operation of the Slave
  Vehicles integrated subsystems in conjunction
  with the Ground Station and the Master Vehicle
• Communications System Test
• Goal To verify proper operation of the
  communications system prior to integration with
  the SOARS system

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Ground Station System Test

• Procedure
• Place master and slave within LOS of the ground
  station
• Have ground station request image from slave
  through the master
• Record time requested and time elapsed to ground
  station display
• Verify location of the slave and master with
  handheld GPS receiver

• Test Location Arvada Associated Modelers Club

Stationary
2 km
1 km
Stationary
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Master Vehicle System Test

• Procedure
• Launch the master and place on station 2 km from
  the ground station and place the slave within LOS
  of the master
• Have ground station request image from slave
  through the master
• Record time elapsed to ground station display
• Ensure flight endurance of 20 minutes

2 km
1 km
Stationary
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Slave Vehicle System Test

• Procedure
• Launch master and slave and place on station at 2
  km and 1 km, respectively
• Have slave conduct target run on field setup
• Record time elapsed to ground station display
• Ensure slave flight endurance of 10 minutes
• Observe test images

Target
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Communications System Test

• Connect Test Procedure
• Use internal testing option of communications
  system program
• Plug both radios into two different USB ports on
  the same computer
• Run test program for 10 minutes
• Save file
• Repeat test for varying time and test settings
  (continuous, break on error)
• Range Test Procedure
• Plug both radios into two different USB ports on
  two different computer
• Place computers 2 km apart at test field and
  verify distance through a handheld GPS receiver
• Run same settings as in previous test to ensure
  proper operation for communications system

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Hardware Integration Flow Chart

• Slave

3 Cell/ 910mAh LiPo Battery
6 Ch Futaba receiver
Autopilot
ESC
Throttle Servo
380 Brushed motor (Ducted Fan Unit)
Elevon Mixer
Elevon Servos
Imaging (camera)
Master
Futaba 6EXS Controller
Futaba 6 Ch. receiver
ESC
Throttle Servo

• - Blue boxes denote isolated subsystem components
• - Orange boxes denote primary integrated
  subsystems

Elevator/Aileron Servos
GUI (Laptop)
Ground Transceiver
Slave
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Imaging Camera Choice
Study Results the C328-7640 Camera Module will
be our initial imager
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Imaging Specific Requirements

• We can now calculate maximum imaging range using
  Johnson Criteria (80 m)
• Given this range, we can calculate maximum pitch,
  yaw, roll, and velocity and ensure our chosen
  airplane conforms to these requirements in its
  planned flight path
• Max tangential velocity 60 m/s
• Max radial velocity 80 m/s
• Max pitch/yaw 0.2 rad/s
• Max roll 2 rad/s

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Imaging Fulfillment of Requirements

• We will fly our airplane at a cruising speed of
  17 m/s (40 mph) directly over the target, imaging
  at just under max imaging range
• Altitude 45 m (allows for error in altimeter)
• Satisfies all blur requirements
• Pitch Rate 0.1 rad/s (lt0.2 rad/s)
• Yaw Rate 0 rad/s by definition of flight path
• Roll Rate 0 rad/s by definition of flight path
• Radial Velocity 8 m/s (lt80 m/s)
• Tangential Velocity 15 m/s (lt60 m/s)
• Imaging window time of 3 seconds

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Power Ducted Fan Test

• Measured Baseline Normal and Axial Forces in Wind
  Tunnel with Motor Off
• Measured Forces With Motor On
• Results Inconclusive
• Reexamine Test Set Up

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Power - Backup

• Normal Force Plot

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Power Motor Test

• Measure Ducted Fan Forces and Motor Power
  Consumption
• Speed 370 Brushed Motor
• 0.8 W Resistance
• 5.5 Minutes

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Power - Conclusions

• Need to Increase Battery Capacity
• Current 910 mAh (stock) lasts 5.5 min
• Need 1800 mAh for gt8 min
• Found Pro Lite 11.1 V, 20C discharge battery

Battery Capacity Mass (g) Volume (mm)
ElictriFly GPMP0815 910 mAh 79 20 x 34 x 62
Pro Lite TP20003 2000 mAh 120 19 x 47.6 x 63.5
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Electrical Design Master UAV Comm Board
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Electrical Design Slave UAV Daughter Board
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Project Risk
Software Failure
Cannot control aircraft to requirements
Failure of communications relay
Microcontroller cannot handle all operations
Battery endurance not to requirement
Unable to take picture in desired location
Payload Mass too High
LOW Medium High
Impact on System
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Facility Requests

• Wind Tunnel
• Dynamic thrust test and battery power testing.
• Table Mountain Radio Quiet Zone
• Secured for flight testing of slave, master and
  ground system.
• Aerospace Electronics Lab

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Schedule Overview

• Aircraft Selection and Stability
• Power and Electrical
• Imaging
• Controls
• Communications
• Software/Electrical Hardware
• Safety/Testing
• Management
• Presentations/Documentation

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Schedule (Slide 1)
78
Schedule Software (Slide 2)
79
Schedule Integration and Testing
80
Schedule Project Management
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Control System Requirements

• Path Tracking
• Altitude Control
• Slave
• Path tracking to allow imaging of target
• Master
• Circular loiter

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Control System Selection

• Using existing graduate student board
• Modifying autopilot
• Consists of developing new vector field
• New model and controller to fit different
  aircraft

83
Design and Verification Process

• Design of vector fields for trajectory tracking
• Verifying vector field via particle simulation
• Model aircraft dynamics and controller design
• Verification of system via Simulink Model
• Flight Test

84
Vector Field Design

• Globally attractive
• Field switched for individual targets

85
Master Vector Field

• 300m Diameter Loiter Circle

86
Altitude Control

• Throttle Control
• Elevon Control
• Combination

87
Camera Mounting

• Camera module is embedded in the foam wing, far
  enough away from the fuselage to prevent blocking
  the FOV

PCB and CMOS sensor
Camera Lens
Pylon Attachment Point
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Slave UAV Interconnect Diagram
Power
Data
Battery

-
16 gage high-current wire
4-Channel Bus
PWMBus
Autopilot
ESC
RC Receiver
Motor
Servos
Camera Power Interface Board
Asynchronous Serial Bus
Camera Module
89
Master UAV Interconnect Diagram
Power
2.4 GHz Antenna 1
2.4 GHz Antenna 2
Data
Comm Board
RF Coax
RF Coax
Battery

-
16 gage high-current wire
4-Channel Bus
PWMBus
Autopilot
ESC
RC Receiver
Motor
Servos