Ocular Prosthesis Team Members: Adam Lee, EE Faculty Advisors: May0013 Team Members: Adam Lee, EE Juhaidi Abd-Hamid, EE Ryan Littler, CprE Brian Mestan, CprE Faculty Advisors: Dr. Ralph Patterson III Dr. Charles Wright

Presentation Overview General Background End-product Description Technical Solution Electrodes, Filter/Amplifier Circuit Microcontroller Design Wheelchair Interface Milestones Budget Conclusion Questions

General Background Severely disabled are unable to perform everyday tasks due to loss of muscle control. In many cases, basic eye movement is retained. Eye motion can be detected allowing the disabled access to a variety of devices. Previous work in this field: Utah Arm, Eye mouse, ISU wheelchair Our project focuses on using eye movement to control a wheelchair.

End-Product Description Interface to control an electric wheelchair using eye movement rather than joystick. Features: Controlled by simple eye movements and combinations Safety features Full 360-degree movement Compact to fit on wheelchair Shock and temperature resistant Inexpensive

Electrooculogram Signals Biological phenomenon (like ECG, EEG) Small positive charge at front of the eye Micropotential created by eye movement (50–100uV) Electrodes can detect this potential in regions around eyes

Technical Description

Filter/Amplifier Design Function: Convert micropotentials into useable input for microcontroller.

Filter/Amplifier Design Problem/Solution: Research to determine best placement and type of electrodes. Small signal levels(50-100uV) – Amplification. Noisy signals – Filtering.

Filter/Amplifier Design Implementation: Instrumentation Amplifier High-Pass Filter Amplification Offset Adjust Voltage Converter Low-Pass Filter

Microcontroller Design Functions: Decode eye movements into corresponding wheelchair movements. Provide emergency stop capability and other safety features. Distinguish “real commands” from noise and errant signals.

Microcontroller Design Problem/Solution:

Microcontroller Design Implementation: MCHC11A1FN 8bit – 8 channel A/D 256byte internal RAM, 32KB battery-protected static RAM 2MHz system clock Interactive C compiler Development on MIT Handy Board

Wheelchair Interface Function: Emulate joystick of wheelchair using signals from microcontroller.

Wheelchair Interface Problem/Solution: Cannot use the microcontroller output directly to control wheelchair. Circuit is needed to convert microcontroller outputs into signals that are typically seen from the joystick.

Wheelchair Interface Implementation: Wheelchair based off 6V signal. To move chair – 6V signal is raised or lowered by summing with signal from microcontroller. Op-amps used to implement summing circuit. Circuit is tuneable to select base speed and precision of movement.

Milestones Project success measured by completion of: Research on placement/type of electrode for system (100%) Design of amplifier and filter electronics (70%) Design of microcontroller system (10%) Design of interfacing circuitry (70%) Subcomponent testing: amplifier/filter, microcontroller program, and interface circuitry (20%) System level testing (0%)

Financial Budget

Conclusion Meaningful project with important solution. Proof of concept that could open up a wide-range of other devices to disabled. Inexpensive compared to current IR solution. Areas of Future Work: Universal interface Infrared voltage detection Remote control Serial/USB ports

Questions ?