1. 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

2. Presentation Overview
Problem Statement
Design Objectives
End-product Description
Assumptions & Limitations
Technical Description
Project Planning
Lessons Learned
Conclusion

3. Problem Statement
People suffering from severe disorders, such as ALS and cerebral palsy, are unable to perform basic tasks due to loss of muscle control.
Surprisingly, basic eye movement is left unimpaired.
Eye motion can be detected allowing the disabled access to a variety of devices.
Our project focuses on using eye movement to control a wheelchair.

4. Design Objective
Design an interface to control an electronic wheelchair by using eye movement rather than joystick.
Requirements and constraints:
Controlled by simple eye movements
Safety features
Full 360-degree movement
Compact to fit on wheelchair
Shock and temperature resistant
Inexpensive (~ $100)

5. End-product Description
Basic prototype has been developed that detects electrooculogram (EOG) signals from the body and uses them to control an electronic wheelchair.
Uses simple commands, safe to use, and allows full 360-degree of travel.

6. Assumptions & Limitations
EOG of sufficient strength to use as a control signal.
Similar EOG signals across users.
Similar EOG signals for similar electrodes.
Correct placement of electrodes.

7. Assumptions & Limitations
Simple eye movements for commands = only simple wheelchair motions.
Device must be “tuned” for each user.
Wheelchair must stop before turning.
Forward movement may begin off-center.
New electrodes required for each session.

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

9. Technical Description

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

11. Filter/Amplifier Design
Problem/Solution:
Research to determine best placement and type of electrodes.
Small signal levels(20-50uV) – Amplification.
Noisy signals – Filtering.

12. Filter/Amplifier Design
Implementation:
Instrumentation Amplifier
High-Pass Filter
Amplification
Offset Adjust
Microcontroller

13. 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.

14. Microcontroller Design
Eye movement decoding:
Look Up = High voltage
Look Down = Low voltage
Look Right = High voltage
Look Left = Low voltage
Blink = similar to a look up

15. Microcontroller Design
Eye movement encoding:

16. Microcontroller Design
Eye movement decoding:

17. Microcontroller Design
Eye movement decoding:

18. Microcontroller Design
Eye movement decoding:

19. Microcontroller Design
Eye movement decoding:

20. Microcontroller Design
Eye movement decoding:

21. Microcontroller Design
Eye movement decoding:

22. Microcontroller Design
Eye movement decoding:

23. Microcontroller Design
Eye movement decoding:

24. Microcontroller Design
Eye movement decoding:

25. Microcontroller Design
Eye movement decoding:

26. Microcontroller Design
Eye movement decoding:

27. Microcontroller Design
Eye movement decoding:

28. Microcontroller Design
Eye movement decoding:

29. Microcontroller Design
Implementation:
Development on MIT Handy Board

30. Microcontroller Design
Implementation:
MCHC11A1FN
8bit – 8 channel A/D
32KB battery-protected static RAM
2MHz system clock
Interactive C compiler – allows multitasking

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

32. 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.

33. Wheelchair Interface Implementation: Wheelchair based off 5.9V signal.
To move chair – 5.9V signal is raised or lowered by summing with signal from microcontroller.
Op-amps used to implement summing circuit.

34. Demonstration

35. Milestones

36. Future Work Further development of this design with the
following features:
Smoother wheelchair motion.
More accurate wheelchair motion.
Self-adjusting circuitry for Amplifier/Filter.
Speed control.
All purpose interface (control other devices).

37. Financial Budget
* Donated

38. Team Effort

39. Lessons Learned General project skills: Technical skills:
Project planning
Distribution of work
Adhering to project milestones
Communication among team members
Weekly meetings with advisor
Technical skills:
C programming and multitasking
Amplifier and filter design
Biomedical engineering (in form of EOG)

40. Conclusion Designed basic prototype for future development.
Meaningful project with important solution.
Proof of concept that opens up a wide-range of other devices to disabled.

41. Questions ?