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Midway Design Review Team Vibraid November 2013 Michael Balanov (Mike) EE Reona Otsuka (Leo) EE Vibraid Spyridon Baltsavias (Spiros) EE Andrew Woo (Andy) EE 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 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 Physical Design • Waist Belt • • • Intuitive polar representation Horizontal orientation Relatively minimum obstruction Requirements Table Specification Value Circumference 75-105cm (small-large) Width <10cm Thickness <2cm Weight <1kg Previous Block Diagram Revised Block Diagram MDR Focus 4 4 4 8 4 4 variable resistance switch signal • Main changes: • • • No Arduino – hardware implementation Filtering No light output variable resistance 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 Input Block • Purpose: • • • Record sufficient sound data Specification Value Pass it on for processing in a format suitable for amplitude comparison Detection Directionality 4 directions Detection frequency range 100Hz to 10kHz, 90% of time Detection radius for 50dB-120dB sound within frequency range >3m (10ft), 90% of time Microphone characteristics: • • • 4 omnidirectional microphones (Freetronics.com) Vendor provided frequency response: 60Hz to 15kHz 2 outputs • • • Requirements Table AC audio voltage “SPL” output DC voltage proportional to amplitude Mics placed in 4 locations (right/0°, front/90°, left/180°, back/270°) 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 Microphone Frequency Response SPL Voltage Vs Frequency 2 1.8 1.6 SPL Voltage (V) 1.4 1.2 1 0.8 0.6 0.4 0.2 0 0 2000 4000 6000 8000 Frequency (Hz) 10000 12000 14000 Microphone Sound Detection Test (2 microphones) Mic A Radius R 15 in Mic B Corresponding angle for each microphone 90/270 135/315 Mic A 45/225 0/180 180/0 Mic B 225/45 270/90 315/135 Degree relative to Mic A/ Degree relative to Mic B Mic SPL Voltage Reading for various angles R = 10 inches Mic #/Degree 0 45 90 135 180 1 0.33 1.49 2.82 1.36 2 1.61 1.47 2.23 3 1.22 1.52 2.87 4 1.52 225 270 315 0.88 1.40 1.01 1.39 1.83 1.30 0.85 1.41 1.31 1.47 1.06 1.52 1.34 1.28 1.52 2.42 1.60 0.83 0.53 1.21 0.88 Mic #/Degree 0 45 90 135 180 225 270 315 1 1.52 0.88 1.60 1.09 0.15 0.52 0.10 0.24 2 1.46 0.70 1.96 0.81 0.83 1.45 1.44 1.28 3 0.50 1.16 1.79 1.60 1.13 0.86 0.79 1.08 4 0.48 0.40 1.57 R = 15 inches 0.69 0.05 1.18 0.08 0.41 Example Mic comparison Radius = 10 inches 2.87/1.21 (1) 1.47/0.88 (1) 1.06/1.52 Mic 1 (1) (2) (1) (1)/(2) 1.52/1.52 (#) = Stronger Mic at 1.52/0.53 given location Mic 2 (2) 1.34/2.42 1.22/0.83 (2) 1.28/1.60 Voltage output of Mic 1/ Voltage output of Mic 2 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 Input Block pt.2 • “SPL” output Envelope Detector Design Input – DC Block – Amplification Amplification – Rectification– Smoothing 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 Requirements Table Specification Value Vibration Directionality Simultaneous vibration in 2 adjacent locations Vibration response time <o.5sec Processing Block Circuit Comparator/Sensitivity Logic DC testing Input 1 (V) Input 2 (V) Output (V) 0.02 0.02 -0.91 0.02 2.43 -0.91 0.02 4.91 -0.91 2.43 0.02 4.33 2.43 2.43 -0.91 2.43 4.91 -0.93 4.91 0.02 4.33 4.91 2.4 4.33 4.91 4.91 -0.92 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) Requirements Table Specification Value Vibration Directionality Simultaneous vibration in 2 adjacent locations Vibration to corresponding detection 99% of times Vibration response time <o.5sec Output Block Circuit Input 1 (V) Input 2 (V) -0.91 -0.91 4.33 4.33 -0.91 4.33 -0.91 4.33 NAND output (V) 4.75 4.83 4.82 0.00 Inverter output (V) 0.01 0.01 0.01 4.91 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 Requirements Table Specification Value Tunable sensitivity Block-all till pass-all Tunable frequency detection 4 modes: full range, 100Hz to 4kHz, 4kHz to 7kHz, 7kHz to 10kHz Tunable motor strength No vibration (0V) to Max supply (5V) Output and Interface Potentiometers Microphone sensitivity Motor strength Summary of Requirements Specification Value Belt circumference 75-105cm (small-large) Belt width <10cm Belt thickness <2cm Product weight <1kg Detection directionality 4 directions Detection frequency range 100Hz to 10kHz, 90% of time Detection radius for 50dB-120dB sound within frequency range >3m (10ft), 90% of time Vibration response time <o.5sec Vibration directionality Simultaneous vibration in 2 adjacent locations Vibration to corresponding detection 99% of times Vibration response time <o.5sec Tunable sensitivity Block-all till pass-all Tunable frequency detection 4 modes: full range, 100Hz to 4kHz, 4kHz to 7kHz, 7kHz to 10kHz Tunable motor strength No vibration (0V) to Max supply (5V) Gantt chart 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 Q&A Power Specifications Preliminary Cost Analysis Pros and Cons of Design • Pros • • • Intuitive polar representation Horizontal orientation Adjustable • Cons • • User may need to tuck in their shirt Hand/clothing obstruction "SPL" Voltage vs. Distance 3 SPL Voltage (V) 2.5 2 1.5 75dB voice, matching freq. 1 70dB tone, 440Hz 0.5 0 0 2 4 6 8 Distance (ft) 10 12 14 16