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Eye Movement Measuring System

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Less invasive/faster recovery vs. eye coil implantation. Data conversion ... Complete HTML and Excel versions available online. Eye Movement Measuring System ... – PowerPoint PPT presentation

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Title: Eye Movement Measuring System


1
Eye Movement Measuring System
  • April 10, 2002 Group 9
  • Bonnie Kroll
  • Anica Rothrock
  • Lendy Stuber

2
Eye Movement Measuring System Project Review
  • Project
  • 1) Design an optimal magnet/sensor configuration
    to measure eye movement
  • 2) Implement an algorithm to output accurate
    coordinates with real-time capabilities

3
Eye Movement Measuring System Project Motivation
  • Features
  • Magnet/sensor system
  • Lasts longer than eye coil methods
  • Less invasive/faster recovery vs. eye coil
    implantation
  • Data conversion
  • Currently not available for magnet/sensor system
  • Possibly faster and more accurate than coil system

4
Eye Movement Measuring System Design Requirements
  • System Requirements
  • Magnets
  • Are ? 1mm x 2 mm x 3mm
  • 90 apart
  • Sensors
  • Array cannot obscure vision or be unsafe
  • Optimal if magnets do not pass plane of sensors
  • Must surround magnets
  • Algorithm
  • Samples at a rate of at least 200 Hz
  • Accurate to at least 0.2 degrees

5
Eye Movement Measuring System Analytic Efforts -
Hardware
  • Magnets - Computer modeling of magnetic fields
  • To determine relative strength and orientation of
    magnetic fields within modeled system
  • Flux at surface 1500 Gauss
  • Magnetic field range proportional to 1/r3

6
Eye Movement Measuring System Analytic Efforts -
Hardware
  • Sensors - Configuration testing in EE lab
  • To determine optimal placement and orientation
    for GMR sensors
  • Power supply 5 Volts
  • Sensitivity Range 20mm

7
Eye Movement Measuring System Analytic Efforts -
Hardware
  • Sensor Array Mask- Design considerations
  • Type of plastic
  • Material thickness 3mm
  • Proper shape to fit subject
  • Dimensions 43mm x 44mm x 27mm
  • Attachment of sensors
  • Slot dimensions 1.5mm x 5 mm
  • Attachment of mask to subject
  • Angle of bolt attachment 45º

8
Eye Movement Measuring System Analytic Efforts -
Software
  • Data Analysis - Acquisition/filtration using
    Spike2
  • To compare the sensor output data to known
    position coordinates
  • To reduce noise and produce a cleaner signal
  • Sampling rate 200 Hz
  • Gain 20
  • Offset None
  • Filters Lowpass 30 Hz

9
Eye Movement Measuring System Analytic Efforts -
Software
  • Data Analysis - Creation of useable data
  • To manipulate data and place it into a table
  • To visualize sensor activity in relation to eye
    movement

10
Eye Movement Measuring System Analytic Efforts -
Software
  • Software development - Implementation of
    algorithm
  • To convert the sensor voltage output to X-Y
    position data

11
Eye Movement Measuring System Design Details
  • Overview of System

12
Eye Movement Measuring System Design Details -
Hardware
  • Two Magnet Configuration
  • NIB Magnets
  • Located on outer surface of eye
  • Positioned 90º from each other
  • Oriented North out
  • Optimal position 9mm apart (in 5.5mm radius
    eye)

13
Eye Movement Measuring System Design Details -
Hardware
  • Four Sensor Configuration
  • GMR Sensors
  • Located 6-7mm from magnets
  • Positioned 14x14mm square
  • Oriented perpendicular to magnet dipole

14
Eye Movement Measuring System Design Details -
Hardware
  • Wires/Connectors
  • 34 gauge enamel insulated magnet wire
  • CTM-12-03-L-DV 10 pin socket
  • FTM-12-03-L-DV 10 pin header
  • 30 gauge Kynar insulated wire
  • 1/2 inch 28 gauge ribbon cable
  • Standard 10 pin 0.1 inch IDC connector
  • RG174 coaxial cables
  • CPM88 mini coaxial

15
Eye Movement Measuring System Design Details -
Hardware
  • Amplifier
  • NPI DPA2F Amplifier
  • AD620 Instrumentation Amplifier
  • Data Acquisition box
  • CED Power 1401

16
Eye Movement Measuring System Design Details -
Software
  • Spike2
  • To capture and analyze data
  • Gives a direct link from the data acquisition box
  • Excel
  • To create look-up table
  • To eliminate false data
  • MatLab
  • To create and test the proposed algorithm
  • Provides a large collection of tools, user
    scripts and mathematical library

17
Eye Movement Measuring System Design Details -
Software
  • Algorithm
  • Step 1. Read data in.
  • Step 2. Find nearest neighbor.
  • Step 3. Find direction of acquired point in
    relation to nearest neighbor.
  • Step 4. Create framing region.
  • Step 5. Calculate position in framed region by
    interpolation.
  • Step 6. Output position in degrees.

18
Eye Movement Measuring System Design Details -
Safety
  • DesignSafe
  • Main Concern
  • Safety of subject
  • Other Concerns
  • Maintenance of disease-free environment
  • General workplace safety
  • Proper electrical systems precautions
  • Complete HTML and Excel versions available online

19
Eye Movement Measuring System Material and
Manufacturing
  • Hardware
  • NIB Magnets 2.40
  • GMR Sensors 40.00
  • Versacel Plastic (Mask) 3.00
  • Wires/Connectors 20.00
  • AD620 or NPI Amplifier 80.00 10,000.00
  • CED1401 Data Acquisition Box 7,165.00
  • Software
  • Spike2 1,900.00
  • Matlab 460.00

Total 9,670.40 19,590.40
20
Eye Movement Measuring System Material and
Manufacturing
  • Overview of Manufacturing Process
  • 1. Take subjects measurements
  • 2. Form mask out of Versacel plastic (thermoform
    to fit monkey, drill holes for eyes, nose,
    sensors)
  • 3. Solder 34 gauge magnet wires to sensors
  • 4. Insert sensors into mask
  • 5. Make appropriate connections/ transitions to
    connect sensors to amplifier
  • 6. Connect amplifier to Power CED 1401 data
    acquisition box
  • 7. Connect CED to computer to view data in Spike2

21
Eye Movement Measuring System Conclusions
  • Did we solve the problem?
  • Future directions?
  • What did we learn?
  • What would we do differently?

22
Eye Movement Measuring System Contact
Information
  • Group 9-Eye Movement Measuring System
  • Bonnie Kroll-presenter
  • Anica Rothrock
  • Lendy Stuber
  • bmegroup_at_cec.wustl.edu
  • http//userfs.cec.wustl.edu/bmegroup

23
Eye Movement Measuring System Questions
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