Eye Controlled Operation for Disabled People Using EMG

1. Eye Controlled Operation for Disabled People Using EMG Fahim Ibn Karim (052437) Rashedul Amin Tuhin (052439) Tasnim Manzar (052441) Project webpage: http://eyecontrolled.wordpress.com A Project Presentation by: Supervised By: Prof. Dr. Ashraful Haque EEE Department, IUT

2. Project Overview • EMG signal acquisition from Extraocular Muscles (Eye movement Muscles) • Processing the signals • Simulation and Implementation Objective Helping disabled people to perform several operations (i.e. simple on/off, speed control etc)

3. EMG Overview • EMG – Electromyography • Electromyography measures the electrical impulses of muscles at rest and during contraction. • Amplitudes of EMG signal range between 0 to 10 mV (peak-to-peak) or 0 to 1.5 mV (rms). • Frequency of EMG signal is between 0 to 500 Hz. • The usable energy of EMG signal is dominant between 50-150 Hz.

4. The Human Eye Movement Muscles

5. Extraocular Muscles Notations: • Superior Rectus (SR) • Superior Oblique (SO) • Lateral Rectus (LR) • Inferior Rectus (IR) • Inferior Oblique (IO) • Media Rectus (MR)

6. muscle movements A given extraocular muscle moves the pupil, at the front of the eye, in a specific direction or directions, as follows: • medial rectus (MR)— inward, toward the nose (adduction) • lateral rectus (LR)— outward, away from the nose (abduction) • superior rectus (SR)— upward (elevation) • rotates the top of the eye toward the nose (intorsion) • inward (adduction) • inferior rectus (IR)— downward (depression) • rotates the top of the eye away from the nose (extorsion) • inward (adduction) • superior oblique (SO)— • primarily rotates the top of the eye toward the nose (intorsion) • secondarily moves the eye downward (depression) • tertiarily moves the eye outward (abduction) • inferior oblique (IO)— • primarily rotates the top of the eye away from the nose (extorsion) • secondarily moves the eye upward (elevation) • tertiarily moves the eye outward (abduction)

8. cardinal positions of gaze • Conjugate eye movements • Vergence eye movements • saccadic eye movements • Smooth pursuit movements These movements are simplified • up/right (1.3.5) • up/left (1.6) • Up (1) • Down (4) • right (3) • left (6) • down/right (3,4) • down/left (6,4,2)

9. Electrodes • Plastic piece and snap on for holding electrode elements • Dimension of 1 inch between electrode contacts • 4 electrode extensions and 1 body reference extension

10. Electrodes • EL1 (TDE23) 4mm silver / silver chloride electrodes • plugged into the white and black differential measurement sockets • A third positioned anywhere to make “Isolated Ground”

11. Positions of the Electrodes Positions shown in the diagram above are (right and left): A) Medial frontalis, B) Lateral frontalis, C) Levator labii superioris, D) Zygomaticus major.

12. EMG Amplifier: Preamplifier • Industry standard instrumentation amplifier op-amp (INA2128) • Accuracy: providing high bandwidth at high gain and output offset current • Differential amplifier circuit with 2 inputs • High gain to boost the EMG signals • Body Reference Circuit or Feed Back (OPA2604)

13. EMG Amplifier: Preamplifier Factors to be considered: • Boost signal to TTL standard level (± 5 V.) • Enough gain • Noise/Artifact problem • Filter, stability of electrodes attached to skin, proper grounding • DC offset or bias problem • Bias adjustment

14. EMG Amplifier: Preamplifier Industry standard instrumentation amplifier op-amp (INA2128)

15. EMG Amplifier: Preamplifier BURR-BROWN INA2128 Application Information

16. Preamplifier with Body Reference Circuit (1 channel) EMG Amplifier: Preamplifier (cont.) Gain Equation: Find RG at Gain = 1,000: Find Gain at RG = 22 ohm:

17. EMG Amplifier: Preamplifier (cont.) Preamplifier with Body Reference Circuit (1 channel) Common Mode Rejection Ratio (CMRR) calculation

18. Inverting Summing Amplifier Circuit Sign Changing Circuit (Inverting Amplifier Circuit) Averaging Body Reference Circuit • Common body reference circuit for 4 channels • Using summing amplifier circuit and sign changing circuit For independent R1, R2, R3, and R4: For independent R1, and R2: For R1= R2= R3= R4: For R1= R2:

19. Averaging Body Reference Circuit Average Body Reference Circuit

20. Averaging Body Reference Circuit Common Body Reference Output:

21. EMG Amplifier: Filter • Suppress noise that has been amplified by the preamplifier • Help to sink any DC current that cause bias to the output • Select particular signal frequency range • Use RC High Pass Filter of 12 Hz

22. EMG Amplifier: Filter (cont.) 1st orderRC High Pass Filter with Cutoff Frequency of 12Hz 1st order RC High Pass Filter Cutoff Frequency: Cutoff Frequency of 12 Hz:

23. Amplifier and Bias Adjustment • Provide abilities to amplify and adjust reference level of output signals • Individual amplifier and bias adjustment unit for each channel • Use Non-Inverting circuit for amplifier unit • Use Voltage Follower Offset Adjustment circuit for bias adjustment unit • Provide Gain of 21 times • Provide Offset of ± 9 volts

24. Amplifier and Bias Adjustment Ideal Non-Inverting Amplifier Circuit Non-Inverting Output:

25. At : At : Amplifier and Bias Adjustment Amplifier Circuit with Gain Adjustment Amplifier Circuit with Gain Adjustment Amplifier Gain: Computing the value of R34 :

26. Amplifier and Bias Adjustment Output of the circuit: Offset Adjustment for Voltage Follower

27. volts ) Case 1: at 0% of : ( ohms; volts ) Case 2: at 50% of : ( ohms; Bias Adjustment Circuit Case 3: at 100% of : ( ohms; volts ) Amplifier and Bias Adjustment Output of the circuit:

28. volts ) Case 1: at 0% of : ( ohms; volts ) Case 2: at 50% of : ( ohms; Bias Adjustment Circuit Case 3: at 100% of : ( ohms; volts ) Amplifier and Bias Adjustment Output of the circuit:

29. Limitations of gain and bias adjustment • The output can not exceed +9V or -9V (power supply voltage). • If 2 volts fed and gain is 3 and offset is +2 volts, then the output is [(2x3)+2]=8 volts, and we are ok with it. But If 2 volts fed and gain is 10 and offset is -9 volts, then it gives [(2x10)-9]=11 volts, but opamp will still produce 9 volts.

30. Future work (Brainstorming … ) • A/D conversion, Normalizing and processing the EMG signals • Simulation and Modification (if needed) • Logic Design for performing different actions • Simulation with MATLAB and Documentation • Code, Code and Code for PIC microcontroller • Implementation to perform several operations (i.e. simple on/off, speed control etc)

31. Pre AMP RC filter Amp with Bias adjustment EMG amp device Project Block Diagram input Simulation EMG capture prog. EMG capture software ADC ADC Computer MCU/Control circuit output

32. Sources • S. Siriprayoonsak: "Real-Time Measurement of Prehensile EMG Signals," thesis defense, August 24, 2005, SDSU • Gianluca De Luca: Fundamental Concepts in EMG Signal Acquisition, 2001 Rev.2.1, March 2003, DelSys Inc • Sylvia Ounpuu: Electromyography (EMG) Fundamentals & Interpretation 6/14/1999 Chaoyang University of Technology • "Cursor Control Using Voice and Facial EMG Signals", by Grant Connell

33. Q & A

34. Thank you for patient hearing.