Image Acquisition and Processing of Remotely Sensed Data (ImAP RSD)

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Image Acquisition and Processing of Remotely
Sensed Data (ImAP RSD)

• Dec08-01 Inertial Measurement Unit (IMU)
• Team Luis, Julian, Amar, Matt
• Client Matthew Nelson - Space Systems and
  Controls Lab (SSCL)
• Advisor Dr. Basart

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Presentation Outline

• Background/History
• Requirements Specification
• Project Plan
• Design
• Testing/Verification on IMU system
• Project Evaluation

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Background/History
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ImAP RSD Motivation

• Methods of monitoring crop health over large
  areas are currently cost and labor intensive
• Airplane
• Manual Inspection
• ImAP RSD initiated by SSCL HABET program to
  develop an improved method of monitoring crop
  health
• Automated photography via high-altitude weather
  balloon
• Accomplished by integrating multiple subsystems
  including
• Horizon Detection, Inertial Measurement Unit,
  GPS, Processing, and Camera systems

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ImAP RSD Concept Sketch
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ImAP System Description

• The ImAP RSD system will be mounted as a payload
  attached to a high-altitude weather balloon.
• The onboard sensor systems will be used to
  determine payload flight path and orientation
• This system will capture images at predetermined
  waypoints using flight prediction software
• Collected field images will be analyzed to
  extract image intensities and make geometric
  corrections
• The corrected images will be transferred to a
  plant pathology team who will interpret the
  images

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Horizon Detection System

• Developed by previous team to determine pitch and
  roll
• Thermopile System
• Compares sky and ground temperatures to determine
  horizon
• Image System
• Aquires images and uses DSP to determine horizon
• Completed in Spring of 2008

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Requirements Specification
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Dec08-01 Problem Statement

• The ISU SSCL requires an Inertial Measurement
  Unit (IMU) and data logging system for the ImAP
  RSD project.

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Block Diagram
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Operating Environment

• The payload will operate at altitudes from 20,000
  30,000 feet
• The payload will experience temperatures ranging
  from -40 to 80C

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User Interface

• RCA power jack
• 11V
• Serial Port
• RS-232
• BCD to primary processor
• Logomatic universal data logger
• SD Card
• Post Flight Analysis

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System Requirements

• Functional Requirements
• FR01 IMU shall measure balloon oscillation
  frequency and angular rotation rate to 1.215
  degree per second.
• FR02 IMU shall measure linear acceleration to
  0.01g for each of the three principle axes.
• FR03 Data logging system shall log at a 100HZ
  rate with 10 bit or greater precision.
• FR04 IMU shall operate over a temperature range
  of -25 C to 85 C
• Non-functional Requirements
• NR01 IMU shall receive power from a 11.1V
  nominal lithium-ion battery
• NR02 IMU shall function for a minimum of 2 hours
  using a 4 Amp-hour battery
• NR03 IMU may measure temperature and voltage
  levels during flight.

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Market Survey IMU

• Commercial IMUs
• SEN-00839 IMU with 2 degrees of freedom for
  99.95
• Inertia-Link-2400-SK1 IMU for 2795.00
• Military grade IMUs
• Buying an IMU would defeat the purpose of a
  student project

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Deliverables

• Project Plan v
• Design Report v
• Final Report
• Project Poster v
• IRP Presentation
• IMU v
• IMU User Manual v

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Project Plan
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Work Breakdown Structure S08
Personnel Gyro and Accelerometer Research Microcontroller and Flash Memory Research Gyro and Accelerometer testing Microcontroller and Flash Memory Testing/Programming Operational Manual Documentation, planning organization Total Hours
Luis 20 10 20 18 20 30 118
Julian 10 20 10 35 20 20 115
Matt 25 8 20 15 15 30 113
Amardeep 20 10 20 20 25 20 115
Total 75 48 70 88 80 100 461
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Work Breakdown Structure F08
Personnel IMU Circuit Board Design Testing for Data Acquisition Gyro and Accelerometer Calibration System Integration Operational Manual Documentation, planning organization Total Hours
Luis 30 25 25 25 20 125
Julian 50 7 35 20 20 132
Matt 30 35 15 20 20 120
Amardeep 40 25 10 25 25 125
Total 150 92 85 90 85 502
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Resource Requirements
Estimated Hours
Estimated Cost
Insert Parts list cost
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Project Schedule S08
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Project Schedule F08
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Risks

• Unfavorable weather
• Continue or cancel mission
• Power Failure
• Schedule another flight

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Design
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Theory of Operation
An accelerometer coupled with a rate gyro can
efficiently be used for attitude determination
purposes. Rate gyros measure angular rotation
rates. By subtracting out known linear
accelerations, an accelerometer can be use as a
tilt measurement device. These two angles can be
combined in an optimal fashion to accurately
determine attitude.
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Pendulum Model of HABET system
The HABET balloon and payload system has been
modeled as a simple, 2-D rigid pendulum. From
this model we can determine angular rates, as
well as the normal and tangential components of
acceleration that the payload will experience.
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Rate Gyro Model
The equation of motion on the left can be
numerically integrated to obtain rotational
rates. This model is only for roll/pitch rates.
These rotational rates will help us choose the
appropriate rate gyro for our project. We have
simulated this model on Simulink. The results
follow.
Fig. Model for determining roll/pitch rates.
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Rate Gyro Simulink Model
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Rate Gyro Simulink Results
Results Roll/pitch rates under 75/sec. From
past data, we have determined that yaw rates
typically range from 20- 50. FFT results
suggest a sampling rate greater than
90Hz. Conclusion Rotational rates and sampling
rate obtained from math model meet functional
requirements. Rate gyro used in this project,
MLX90906, measures 300deg/sec, which satisfies
both functional requirements and math model.
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Accelerometer Model
By assuming a simple pendulum, the acceleration
equation reduces to the one boxed in red. This
equation measures tangential and normal
components of acceleration. These acceleration
values will help us choose the appropriate
accelerometer for our project. We have simulated
this model on Simulink. The results follow.
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Accelerometer Simulink Model
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Accelerometer Simulink Results
Results Greatest magnitude of acceleration
expected is under 1.5g. FFT results suggest a
sampling rate greater than 80Hz. Conclusion Acce
leration and sampling rate obtained from math
model agree with our functional requirements.
Accelerometer used in this project, MMA7260Q,
measures 2gs, which satisfies both functional
requirements and math model.
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Data Storage Space and
We are required to log for a maximum of 3 hours.
A 1 GB SD Card will be used for data
storage Using a baud rate of 19200 symbols/sec,
we can log for approximately 28 hrs (maximum) at
this rate
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Electric schematic
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Mechanical CAD of IMU Casing and PCB boards
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Power Budget
Device Maximum I A Quantity Flight Duration hr Amp-Hours
MMA7260Q Accelerometer .0008 1 3 .0024
MLX90609 Gyroscope .02 3 3 .18
ATMega128 .019 1 3 .057
Logomatic .08 1 3 .24
LM78XX Voltage Regulator .008 1 3 .024
The power budget for the IMU components totals at
.5034 Amp-Hours and will be powered by a 4.8
Amp-Hour battery leaving 4.2966 Amp-Hours for
other systems.
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Software Flow
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Testing/Verification of IMU system
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Rate Gyro Testing/Calibration

• Calibration
• EMI effects Electromagnetic interference
  degrades or obstructs the performance of the
  circuit.
• Output verification using test platform
• Encoder test platform ?
• Rate gyro ? angular rate
• We compare it by differentiate and
  angular rate

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Accelerometer Testing/Calibration

• Calibration
• EMI Shielding Electromagnetic interference
  degrades or obstructs the performance of the
  circuit.
• Tilt measurement using test platform

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Test PlatformRotations
Maximum 400deg/s
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Test PlatformAccelerations
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Accelerometer Tilt Angle Measurements
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Project Evaluation
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Earned Value Analysis
Spring 2008
Tasks Budgeted Hours Actual Hours BCWS BCWP ACWP
IMU Research 75 72 750.00 750.00 720.00
MCU Research 48 42 480.00 455.00 420.00
Sensor Testing 70 75 700.00 684.00 750.00
Programming/SW Debugging 88 760 880.00 810.00 760.00
Documentation 100 109 1,000.00 984.00 1,090.00
Subtotal 3,810.00 3,683.00 3,740.00



Fall 200
Tasks Budgeted Hours Actual Hours BCWS BCWP ACWP
IMU Design 150 173 1,500.00 1,430.00 1,730.00
Testing/Data Acquisition 92 123 920.00 850.00 1,230.00
Sensor Calibration 85 46 850.00 810.00 460.00
System Integration 90 104 900.00 850.00 1,040.00
Operation Manual 85 60 850.00 815.00 820.00
Subtotal 5,020.00 4,755.00 5,280.00

Total 8,830.00 8,438.00 9,020.00
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Earned Value Analysis
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Earned Value Analysis
Schedule Variance BCWP-BCWS -392 Behind Schedule
Cost Variance BCWP-ACWP -582 Over Budget
Cost Performance Index BCWP/ACWP 0.935476718
Schedule Performance Index BCWP/BCWS 0.955605889
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Conclusion/Lessons Learned

• We spent more hours on the project than
  anticipated.
• The system integration and debugging consumed
  most of our time.
• We tried to make the system as simple as
  possible.
• The assumptions can be wrong for the same
  component made by different supplier and buffers
  for this should be accounted.
• Ask for expert help sooner.

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References

• Dynamics of Flight, Stability and Control B.
  Etkin, L. Reid. John Wiley and Sons, 1996
• Aurzkai et al. ImAP Fall 2007

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Appendix
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Euler angle rates
p,q,r are angular rates measured by the rate gyro
in the body frame. To transform into the inertial
frame, we utilize the transformation matrix, T.
We run this through RK4 and produce the desired
angles, and thus the payload attitude.
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Acceleration on a point b with respect to CM on
an arbitrary object.
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Tilt Calculations
Vout Output of Accelerometer Voffset 0g
offset of Accelerometer 1g Earths Gravity
Angle of tilt
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Hardware

• 3 MLX90609 1-axis Gyroscope
• 1 ADXL330 3-axis Accelerometer
• 1 GB SD Card
• 1 Atmel Mega 128 Processor
• 1 Logomatic SD Data Logger
• Various Electrical components (resistors,
  capacitors, etc)

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HardwareMLX90609 Gyroscope

• Requirement
• Measure angular rotation to 300 degrees per
  second for each of the three principle
  axes(FR01). Operational temperature
  -40-85C(FR06).
• Reasons for choosing this part
• The MLX90609 is a 1 axes gyro that includes a
  breakout board for
• evaluation purposes.
• Measures 300 /s which is not excessive and will
  not have resolution issues,
• but also measures more than the required
  specifications.
• Low Price 59.95
• The selling point of this gyro is the angular
  rate measurement and the temperature
• range.

Rate Gyro MLX90609 ADXRS150 IDG-300
Full Range 300 /s 150 /s 500 /s
Noise Performance 0.03 /s/vHz 0.05 /s/vHz 0.014 /s/vHz
Sensitivity 0.006V//s .001 V//s 0.002 V//s
Temperature Range -40-85C -40-85C 0-70C
Price 59.95 69.95 74.95
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HardwareADXL330 (Accelerometer)

• Requirements
• Measures linear acceleration to 0.01g for each of
  the three principle axes(FR02). Operational
  temperature -40-85C(FR06).
• Reasons for choosing this part
• Includes a breakout board which will make the
  evaluation process easier.
• Very low noise density 280µg/vHz rms
• Very good sensitivity change due to temperature
  0.015/C
• Non-linearity 0.3
• Low Price 34.95

Accelerometer ADXL330 LIS3LV02DQ MMA7260Q
Full Scale 3.6g 2g 1.5g
Sensitivity Vs Temperature .015 /C .025 /C .03 /C
Non-Linearity 0.3 3 1
Price 34.95 43.95 39.95
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HardwareAtmel Mega 128 Microprocessor
Requirements Power and weight Reasons for
choosing the part light weight price
Microcontroller Atmel mega 128 Pic 18 series
Throughput 16 Mhz 10Mhz
Flash program memory 128 KBytes N/A
On chip RAM 4 KBytes 512 16384 Bytes
Price 100 129
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HardwareLogomatic Serial SD Data Logger

• Requirements
• We needed some system that had the FAT system
  ready to use. There is a lot of code that has to
  be written to be able read anything legible from
  the SD card
• Reasons for Choosing this Part
• Automatically logs incoming data from the UART
  (saves time, and power)
• Comes with a lot of FAT16/32 code for free on
  Sparkfun.com (saves a lot more time)
• Has a place holder for the SD card which saves
  spaces
• An alternative was the DosOnChip (44.95) board
  which also utilizes a FAT system , but it has
  really poor documentation and is unavailable
  indefinitely.
• Price 59.95