Midway Design Review

Team Vibraid

November 2013

VibraidMichael Balanov(Mike) EE

Spyridon Baltsavias(Spiros) EE

Reona Otsuka(Leo) 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

• Main changes:

• No Arduino – hardware implementation

• Filtering

• No light output

44

4 4 4 8

switch signal

variable resistance

variable resistance

MDR Focus

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

• 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°)

Requirements Table

Specification Value

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 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

0 2000 4000 6000 8000 10000 12000 140000

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

SPL Voltage Vs Frequency

Frequency (Hz)

SPL

Volt

age (

V)

Mic B

Mic A

Radius R

Microphone Sound Detection Test

(2 microphones)

15 in

Mic B

Mic A

Corresponding angle for each microphone

0/180

225/45

180/0

135/315

90/270

45/225

270/90

315/135

Degree relative to Mic A/Degree relative to Mic B

Mic SPL Voltage Reading for various angles

Mic #/Degree

0 45 90 135 180 225 270 315

1 0.33

1.49

2.82

1.36

0.88

1.40

1.01

1.39

2 1.61

1.47

2.23

1.83

1.30

0.85

1.41

1.31

3 1.22

1.52

2.87

1.47

1.06

1.52

1.34

1.28

4 1.52

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

0.69

0.05

1.18

0.08

0.41

R = 10 inches

R = 15 inches

Mic 2

Mic 1

Example Mic comparison

1.22/0.83

1.52/1.52

1.06/1.52

1.47/0.88

2.87/1.21

1.52/0.53

1.34/2.42

1.28/1.60

Voltage output of Mic 1/Voltage output of Mic 2

Radius = 10 inches

(#) = Stronger Mic at given location

(2)

(1)

(1)

(1)

(1)

(1)/(2) (2)

(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) NAND output (V)

Inverter output (V)

-0.91 -0.91 4.75 0.01-0.91 4.33 4.83 0.014.33 -0.91 4.82 0.014.33 4.33 0.00 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

Motor strengthMicrophone sensitivity

Summary of RequirementsSpecification 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

0 2 4 6 8 10 12 14 160

0.5

1

1.5

2

2.5

3

"SPL" Voltage vs. Distance

75dB voice, matching freq.

70dB tone, 440Hz

Distance (ft)

SPL

Volt

age (

V)