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ImAP RSD Ongo-02a
Image Acquisition and Processing of Remotely Sensed Data
Team Members
Advisor: Dr. Basart Client: Space Systems Control Laboratory
(SSCL) – Matt Nelson Chief Engineer EE 491: Matt Clausman, Jesse Griggs, Christina
McCourt, Andy Schulte, Shobhit Vaish EE 492: Usman Aurakzai, Chia-Yuan Chang
Presentation Outline
Overview of Horizon Detection System System Requirements System Block Diagrams Thermopile System Imaging System Testing Semester Summary Questions
ImAP Overview
Horizon Detection System (HDS)
Absolute frame of reference is not available Reference the ImAP payload pitch and roll to the
horizon (yaw is not accounted for)
ImAP Video
Video taken from High Altitude Balloon Experiments in Technology (HABET) payload at approximately 25,000 feet.
HDS Functional Requirements
Horizon angle accurate to ±3° when operated between 20,000 and 30,000 feet
Minimum sample rate of 10 Hz
Operate during daylight hours
Less than 30% cloud cover
Horizon angle range of ±30°
HDS Functional Requirements
Industrial temperature range of -40°C to +85°C
Powered by 11.1 V nominal lithium-ion battery
3 hour run time using 4 Amp-hour battery pack
Market Research
Horizon detection using imagingMore advanced statistical image
processing algorithmsSupercomputers to process data
Conclusion: Too expensive
Horizon detection using thermopilesLower altitude and using model planeDifferent control scheme
Conclusion: Too simple
System Block Diagram
ImAP Payload
Thermopile Overview
Thermopile System
Measure sky, ground, and horizon temperature
Nominal thermopile accuracy ±1°C (factory calibrated over -40°C to +85°C)
Thermopile resolution 0.02°C
Thermopile time constant 30 ms (-3 dB Bandwidth = 33 Hz)
Thermopile System (continued)
Uncalibrated worst case angular accuracy of ±4°
Used mainly for image processing sanity check by comparing thermopile and imaging systems outputs
Simple temperature and angle calculations
Inexpensive
Thermopile System Algorithm
Average Horizon Temperature:
Angle of Sky in View:
horizon fov 1
2
Tavg Tgnd
Tsky Tgnd
Tavg sky Tsky gnd Tgnd
fov
sky fov Tavg Tgnd
Tsky Tgnd
Horizon Angle:
Thermopile System Process
Thermopile System Hardware
Thermopile Test Board Layout
Thermopile Test Board - Page 1
Thermopile Test Board - Page 2
Thermopile Test Board - Page 3
Thermopile Test Board - Page 4
System Block Diagram
ImAP Payload
Imaging System
Mount horizon facing camera sideways for 640 vertical lines of resolution
0.175° angular resolution
Output horizon line equation and R2 value for least squares fit line
Utilize 3 different algorithms
Imaging System (continued)
Accuracy varies significantly with conditions
Very computation intense therefore requires hardware processing (FPGA)
Expensive
Imaging System Process
Imaging System Blue Algorithm
Imaging System Gray Algorithm
Algorithm Comparison
Disadvantage: Numerous clouds in the sky may cause incorrect horizon detection
Advantage: Performance unaffected by most clouds in the sky
Disadvantage: Incorrectly detects horizon when haze or fog is present near the horizon
Blue Algorithm Gray AlgorithmAdvantage: Performance unaffected by haze or fog near the horizon
Decision Algorithm Count the number of edge
pixels above the estimated horizon fit line
Calculate the trapezoidal area above the estimated horizon fit line
If cloud content is above the threshold value, use Blue Algorithm
If cloud content is above the threshold value, use Gray Algorithm
Cloud content =
Number of edge pixels above line
Total number of pixels above line
Imaging System Hardware
Bus Arbiter
Controls the bus time given to each client
Camera Interface is highest priority, VGA Controller is lowest priority
Allows 64 cycles of uninterrupted transfer
3 cycles overhead for each new read/write operation
SDRAM Controller
Accepts variable length packets
Automatically activates and deactivates rows
Performs Auto-Refreshes
7 overhead cycles for each new read/write operation
Camera Interface
Reads data from CMOS VGA Camera
Buffers data until the bus is available for transfer into SDRAM
Allows triggered or continuous frame acquisition
Each image requires 921 KB of RAM
Imaging System Bus Bandwidth
200 MB/s Bus Speed 64 Byte packets nominal SDRAM Controller 89.1% data throughput Bus Arbiter 95.3% data throughput Overall data throughput 84.9% or 170 MB/s Capable of transferring 184 VGA frames per
second Estimated 12 FPS process rate with 15 frame
transfers to process
HDS Testing
T2
Optical Rotary Encoder Electrical resolution: 256 quadrature
cycles per revolution Angular resolution: 0.351 °
Single axis pivoting table with an optical rotary encoder to measure the horizon angle of the imaging and thermopile systems
Testing Platform
HDS Testing
Test PlatformOptical Rotary
EncoderMicrocontroller Computer
HDS Testing Procedure
Verify the accuracy of the Imaging System Algorithms Use the test platform to compare the angle values
provided by the optical rotary encoder to the horizon angle calculated by the Imaging System
Verify Imaging System hardware and circuit robustness Temperature, humidity, and mechanical shock
HDS Testing Procedure Test thermopile accuracy, precision, and drift
Use a constant temperature black body and data log the thermopile temperature values
Verify Thermopile System Use the test platform to compare the angle values
provided by the optical rotary encoder to the value calculated by the Thermopile System
Verify thermopile hardware and circuit robustness Temperature, humidity, and mechanical shock
Team Hours and Budget
Semester Milestones
Oct 11
• System Design Research• Hardware & Software research
Dec 7• System Implementation
• Horizon Detection Systems
Dec 12
• Documentation• Plan, Design & Final Report
Dec 19
• System Testing• Testing Plan• Actual Testing
Current Accomplishments
Thermopile algorithm determined
Thermopile Test Board layout complete
Image processing algorithms determined
Image processing camera to SDRAM to VGA Controller complete
Next Semester Tasks
Complete testing platform construction
Test and verify thermopile algorithm
Continue testing and verification of image processing algorithms
Implement image processing algorithms in FPGA
Next Semester Tasks
Implement thermopile algorithm in microcontroller
Design and layout single Thermopile and Imaging Systems circuit board
Test and verify Thermopile and Imaging Systems board
Deliver service manual to client (SSCL)
Demonstration
Questions?