System Architecture EOG HCI Electrooculography Human Computer Interface • Currently, 12 million people within the U.S require assistance for ordinary tasks. While computer technology can help individuals with upper body movement disabilities independently handle a wide range of activities, they cannot provide computer inputs with a standard keyboard or mouse. The purpose of this project was to provide these people with a cost-effective control system for home computers. • Electrooculography (EOG) is a technique that measures steady state corneal-retinal potential of the eye balls. EOG signals are collected by two pairs of surface electrodes placed around the eyes. Compared with other biological signals, they have larger amplitude and distinguishable patterns for different types of eye movements. Furthermore, the signals linearly change as eyes rotate away from the center. • Taking advantages of EOG signals, this project developed a low-cost and power-efficient device, “Eye-Mouse” ,which used eye movements to control joystick-like movements of the computer cursor in the four cardinal directions. Using 3D printer, a set of adjustable goggles were designed and fabricated to house the EOG electrodes. Afterwards, a circuit was designed to provide a differential EOG signals on the needed range by the ADC (Analog to Digital Converter) on the microcontroller unit. The circuit was prototyped on breadboard, Vector board and PCB. Following signals were fed to the ADC on the vertical and horizontal channels. Horizontal Movement Introduction Implementation Results 12096.15385 2066.769231 3365.307692 0 2000 4000 6000 8000 10000 12000 14000 Eye-Mouse EOG Verbatim Laser Logitech Optical Time (ms) Comparison of Average Time for 13 Trials Average Time for Movement Vertical Movement 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 Eye-Mouse EOG Microsoft Opticle Logitech Laser R 2 Value Comparison to Minimum Fitts's Law Requirement Performance of Mouse Minimum Requirement of Fitts's Law Movement Result Comparison to Conventional Mice Horizontal 0.264 linear correlation co - efficient 41.1% less performance Vertical 12096 ms average movement time 77.5% slower movement R² = 0.1522 R² = 0.7743 R² = 0.264 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 0 1 2 3 Time (ms) Index of Difficulty Logitech Laser vs Microsoft Optical vs Eye- Mouse EOG Microsoft Opticle Logitech Laser Eye-Mouse EOG Linear (Microsoft Opticle) Linear (Logitech Laser) Linear (Eye-Mouse EOG) y = 10.049x + 3295 y = -2.2857x + 2082.8 y = 680.68x + 7331.4 0 5000 10000 15000 20000 25000 30000 35000 0 5 10 15 Time (ms) Trial Logitech Optical vs Verbatim Laser vs Eye- Mouse EOG Logitech Optical Verbitim Laser Eye-Mouse EOG Linear (Logitech Optical) Linear (Verbitim Laser) Linear (Eye-Mouse EOG) • User wears EOG goggles. • A single cable from goggles connects to The EOG HCI. • USB cable from EOG HCI connects to PC. • Mouse cursor movement is visible on PC Monitor screen. • Cross-platform compatibility. A testing application was designed based on Fitts’s Law. Performance was compared to two other conventional mice: Movement time was compared against two other conventional mice and averages of consecutive movement between the same distance were recorded: Top Level Architecture PC Monitor User wearing EOG Apparatus Electrode Cable EOG HCI PC USB Cable PC Video Output User wearing EOG HCI Spectacles COMPUTER Multi-Channel ADC SAM4S ARM MCU USB CIRCUIT Raw EOG Signal Mouse Movement Algorithm HID Compliant Mouse Movement Digital Horizontal and Vertical Values Mouse Movement Speed and Direction 5V Power Power Filtering Power Convertion Signal Amplification Signal Filtering Signal Differentiation Signal Offset Analog Difference Signal (between 0V to 1V) Level-2 Architecture Digitized signals then are processed on the microcontroller to determine the eye movements. An algorithm was setup for blinks, horizontal, and vertical eye movements to associate them with joystick-like movement of the mouser cursor on the screen. Since Eye-mouse is detected as a generic USB mouse, it is multi- platform compatible.
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System Architecture
EOG HCIElectrooculography Human Computer Interface
• Currently, 12 million people within the U.S require assistance for
ordinary tasks. While computer technology can help individuals with
upper body movement disabilities independently handle a wide range
of activities, they cannot provide computer inputs with a standard
keyboard or mouse. The purpose of this project was to provide these
people with a cost-effective control system for home computers.
• Electrooculography (EOG) is a technique that measures steady state
corneal-retinal potential of the eye balls. EOG signals are collected by
two pairs of surface electrodes placed around the eyes. Compared
with other biological signals, they have larger amplitude and
distinguishable patterns for different types of eye movements.
Furthermore, the signals linearly change as eyes rotate away from the
center.
• Taking advantages of EOG signals, this project developed a low-cost
and power-efficient device, “Eye-Mouse” ,which used eye movements
to control joystick-like movements of the computer cursor in the four
cardinal directions.
Using 3D printer, a set of adjustable goggles
were designed and fabricated to house the
EOG electrodes. Afterwards, a circuit was
designed to provide a differential EOG
signals on the needed range by the ADC
(Analog to Digital Converter) on the
microcontroller unit. The circuit was
prototyped on breadboard, Vector board and
PCB.
Following signals were fed to the ADC on the
vertical and horizontal channels.
Horizontal Movement
Introduction
Implementation Results
12096.15385
2066.769231
3365.307692
0 2000 4000 6000 8000 10000 12000 14000
Eye-Mouse EOG
Verbatim Laser
Logitech Optical
Time (ms)
Comparison of Average Time for 13 Trials
Average Time for Movement
Vertical Movement
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90
Eye-Mouse EOG
Microsoft Opticle
Logitech Laser
R2 Value
Comparison to Minimum Fitts's Law Requirement
Performance of Mouse Minimum Requirement of Fitts's Law
Movement Result Comparison to Conventional Mice
Horizontal 0.264 linear correlation co-efficient 41.1% less performance
Vertical 12096 ms average movement time 77.5% slower movement
R² = 0.1522
R² = 0.7743
R² = 0.264
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
0 1 2 3
Tim
e (
ms)
Index of Difficulty
Logitech Laser vs Microsoft Optical vs Eye-Mouse EOG
Microsoft Opticle
Logitech Laser
Eye-Mouse EOG
Linear (MicrosoftOpticle)
Linear (LogitechLaser)
Linear (Eye-MouseEOG)
y = 10.049x + 3295
y = -2.2857x + 2082.8
y = 680.68x + 7331.4
0
5000
10000
15000
20000
25000
30000
35000
0 5 10 15
Tim
e (
ms)
Trial
Logitech Optical vs Verbatim Laser vs Eye-Mouse EOG
Logitech Optical
Verbitim Laser
Eye-Mouse EOG
Linear (LogitechOptical)
Linear (VerbitimLaser)
Linear (Eye-MouseEOG)
• User wears EOG goggles.
• A single cable from goggles
connects to The EOG HCI.
• USB cable from EOG HCI
connects to PC.
• Mouse cursor movement is
visible on PC Monitor screen.
• Cross-platform compatibility.
A testing application was designed based on Fitts’s Law.
Performance was compared to two other conventional mice:
Movement time was compared against two other conventional mice
and averages of consecutive movement between the same distance
were recorded:
Top Level ArchitecturePC Monitor
User wearing EOG Apparatus
Electrode Cable
EOG HCI
PC
USB Cable
PC Video Output
User wearing EOG HCI Spectacles
COMPUTER
Multi-Channel ADC
SAM4S ARM MCU
USB
CIRCUIT
Raw EOG Signal
Mouse Movement Algorithm
HID Compliant Mouse Movement
Digital Horizontal and Vertical Values
Mouse Movement Speed and Direction
5V PowerPower Filtering
Power Convertion
Signal Amplification
Signal Filtering
Signal Differentiation
Signal Offset
Analog Difference Signal (between 0V to 1V)
Level-2 Architecture
Digitized signals then are processed on the microcontroller to
determine the eye movements. An algorithm was setup for blinks,
horizontal, and vertical eye movements to associate them with
joystick-like movement of the mouser cursor on the screen.
Since Eye-mouse is detected as a generic USB mouse, it is multi-
platform compatible.
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