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Midway Design Review

Midway Design Review. Team Vibraid November 2013. Vibraid. Michael Balanov (Mike) EE. Spyridon Baltsavias (Spiros) EE. Reona Otsuka (Leo) EE . Andrew Woo (Andy) EE. Assistive technology for the deaf community.

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Midway Design Review

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  1. Midway Design Review Team Vibraid November 2013

  2. Vibraid Michael Balanov (Mike) EE SpyridonBaltsavias (Spiros) EE Reona Otsuka (Leo) EE Andrew Woo (Andy) EE

  3. Assistive technology for the deaf community • Fact: Over 5% of the world’s population – 360 million people – has disabling hearing loss • Deaf/hard of hearing people have limited awareness of surroundings • High demand but production of hearing aids meets only 10% of global need • Currently deaf people have to use specific aids for different applications • Expensive • Impractical

  4. Vibraid: Vibration + Hearing Aid • Convert sound to vibration • Research shows haptic feedback usefulness • Lip-reading, frequency detection • Alert user of impending danger/sound source • Enable tactile sound localization

  5. Physical Design • Waist Belt • Intuitive polar representation • Horizontal orientation • Relatively minimum obstruction

  6. Previous Block Diagram

  7. Revised Block Diagram MDR Focus 4 4 4 8 4 4 variable resistance variable resistance switch signal • Main changes: • No Arduino – hardware implementation • Filtering • No light output

  8. MDR Deliverables • PDR proposal: Sound to Vibration & Light • Demo time! • Additional Deliverables: progress towards 2-way directionality • Input Block: • Andy: Microphone requirement testing • Spiros: Envelope Detector design • Processing & Motor Block • Mike: Comparator logic & motor activation • Leo: Sensitivity logic & DC voltage testing

  9. Input Block • Purpose: • Record sufficient sound data • Pass it on for processing in a format suitable for amplitude comparison • Microphone characteristics: • 4 omnidirectional microphones (Freetronics.com) • Vendor provided frequency response: 60Hz to 15kHz • 2 outputs • AC audio voltage • “SPL” output DC voltage proportional to amplitude • Mics placed in 4 locations (right/0°, front/90°, left/180°, back/270°)

  10. Microphone Range Test (Voltages) • Procedure: • Measure “SPL” voltage of noise • Range: 0.00V-0.08V, depending on environment • Measure “SPL” voltage of test-sound • Computer-generated 440Hz tone • Sound directed towards front of microphone • Sound level from 3ft away: ~70dB (measured with dB meter application) • Determine maximum range for which voltage>noise+0.1V • Average Results: • 10ft detection: yes • 15ft detection: no

  11. Microphone Frequency Response

  12. Microphone Sound Detection Test (2 microphones) Mic A Radius R 15 in Mic B

  13. Corresponding angle for each microphone 90/270 135/315 45/225 Mic A 0/180 180/0 Mic B 315/135 225/45 Degree relative to Mic A/Degree relative to Mic B 270/90

  14. Mic SPL Voltage Reading for various angles R = 10 inches R = 15 inches

  15. Example Mic comparison Radius = 10 inches (#) = Stronger Mic at given location 2.87/1.21 (1) 1.47/0.88 1.52/0.53 Mic 1 (1) (1) (2) (1) 1.22/0.83 1.06/1.52 (2) (1)/(2) Mic 2 1.28/1.60 1.52/1.52 (2) Voltage output of Mic 1/Voltage output of Mic 2 1.34/2.42

  16. Test Conclusion and Evaluation Inconsistency across each microphone Unexpected spikes/drops of voltage in some angles Microphones are not completely omni-directional No simple relationship between distance and sound amplitude Consider directional microphones

  17. Input Block pt.2 “SPL” output

  18. Envelope Detector Design

  19. Input – DC Block – Amplification

  20. Amplification – Rectification– Smoothing

  21. Processing Block • Purpose: • Receive sensitivity knob input to determine if microphone input should be received • Receive microphone output in order to compare amplitudes • Determine quadrant of incoming sound • Produce output signal with motor activation information to be read by Output Block

  22. Processing Block Circuit

  23. Output Block • Purpose: • Receives control signals from Processing block • Activates motors in appropriate location • Indicates relative sound amplitude • Motor characteristics • “Coin” vibration motors, used in cellphones • Noticeable vibration on skin • Small voltage rating • 2 motors per key location (front, back, sides)

  24. Output Block Circuit

  25. Interface Block • Purpose: • Allow user customization for three features • Microphone sensitivity • Adjusts the threshold voltage for comparator block • Frequency range detection • Switches between 3 frequency filters and bypass • Motor strength • Modifies the motors strength according to user preference b • Method • Potientiometers for tunable voltage divider • Switch to disconnect and reconnect to desired circuit

  26. Output and Interface Potentiometers • Microphone sensitivity • Motor strength

  27. Summary of Requirements

  28. Gantt chart

  29. CDR Deliverables • Goal: Demonstrate 4-way detection and vibration directionality • Correct quadrant determination • Meet range, frequency specs • Implement working user interface • Prototype filter • Implement levels of motor activation • Portable power supply

  30. Q&A

  31. Power Specifications

  32. Preliminary Cost Analysis

  33. Pros and Cons of Design • Pros • Intuitive polar representation • Horizontal orientation • Adjustable • Cons • User may need to tuck in their shirt • Hand/clothing obstruction

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