Project31 Presentation

8/3/2019 Project31 Presentation

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Active Monitoring andAlerting for Hypotonia of the

Jaw

Shabab Mustafa and Jason Strack

Group 31


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Outline Problem & Solution

List of parts Design

Testing Future work


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Problem

Jaw open forextended periods oftime

Who suffers? Stroke victims Downs syndrome

Effects

Drooling

Embarrassing

Solution

Create a device tomonitor the jawposition

Alert the user whenneeded

Close the jawautomatically


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Our Device

Accelerometer placement Base device placement


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Circuit Block Diagram


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Circuit Diagram (Eagle)


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Batteries

2.4Wh each 3.2V

750mAh

Rechargeable

Fairly safe Non-toxic

Virtually incombustible

No memory effect Expect 3 days of continued use

Two LiFePO4


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Accelerometers

Comes with circuit board

Three axes Only using two axes each

2.23.6V operating voltage We operate at 3.53V

1.65mW power consumption

Sensitive to 3 or 11g We use 3g

Better sensitivity

Mounts to jaw and temple One is stationary reference

One moves with jaw

Added silicone rubber

Two MMA7341Ls


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Microcontroller

1.8-3.6V operating voltage Operating at 3.56V

0.66mW power consumption

8 ADC inputs Using 4 from accelerometer signals

Emits 0.5 second output

MSP430G2231


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Regulators

7805

VIN = 5.5V to 20V

VOUT = 5V IOUT = 1A

UA78M33KC

VIN = 5.3V to 25V

VOUT = 3.3V IOUT = 500mA


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Transistor as a Switch

2N2222A

NPN

400mW VCE,max = 10V

BVEB0,max = 6V

Microcontroller to Timer


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555-timer and Op-Amps

LM555

Timer IC

5V Operation Pmax = 1180mW

Signals for both audioand electric stimulation

LF347

Better than LM374

Quad op-amp 570mW

VCC = 18V

Noise-cancelling and clipping


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Output and Casing

Board-mounted 3.5-mm jack and 3.5-mmheadphones (32 Imp.)

Electrodes

Black box Discrete

Hip-mounted

Easily accessible front-panel


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Building an Oscillator

Initially built an AC oscillator Periodic charging/discharging of capacitors

Needed DC, square wave TENS Unit

Chose 555-timer


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AC Oscillator Output


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555 Monostable Timer (1)


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555 Monostable Timer (2)

1s interval 5s interval


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555 Astable Timer (Stage 1)


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Programming


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Determining Jaw Open

ADC converts 0V to max voltage (3.53V) to values from 0-1023 Accelerometer range is only 238

Change in angle must be calculated

init_accel[i] and accel[i] get digital acceleration readings diff[i] = init_accel[i] accel[i]

i = 0 is accelerometer 1s x-axis, 1 is Y1 axis, 2 is X2 axis, 3 is Y2 axis

angle = arcsin( ((diff[3]/((1-diff[2])/119)) (diff[1] /((1-diff[0])/119)) )/119 )

Microcontroller lacks necessary flash memory for math.h However arcsin(x) can be approximated as x + x3/6 + 3x5/40 + 5x7/112

Only accept 60 change in x1-axis if( (diff[0] > 103) || (diff[0] < -103) ) declare jaw closed

if( angle > 0.524 || angle < -0.524) angle > 30jaw is open


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Timing Microcontroller Signal

Track time, reset if jaw closedtime = wdtCounter / (float)WDT_FREQUENCY/1000;

while ((wdtCounter time) < 3000){if( jawOpen() = 0 ) time = wdtCounter; }

If closed for 3 seconds send signal Signal lasts one half second

After this resumes checking jaw


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Accelerometer Testing

Measured x and y axes Rotated both axes in circles

X-axis voltage 1.15-1.97V

Y-axis voltage 1.18-2.00V Accelerometer 2 not working

Was working before demo

Started acting up around demo

Not working now, do not have

picture


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Microcontroller Testing

Insert angle values in code Check with LED to test microcontroller

Next use actual accelerometersAgain use LEDs to test

Move accelerometers in various positions


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Future Work

Reserve one channel of 3.5mm jack for electrodes

Mount jacks on side panel for easier part replacement Headphones

Accelerometers Sealing

Battery holder

Adjustable frequency Separate timers

Use/manipulate a timer such that low when inactive Circuit protection for electrodes

Thinner wire 30 40 AWG


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Future Work

Could add two 3-axis magnetic sensors

Would measure jaw for all head positions

Would add cost and complexity Could use optical distance sensor instead More simple, but also larger and more power consumption

Test electrical stimulation

Control output wave shape with microcontroller Will reduce needed circuitry, reduce power, give cleaner output

Package everything to fit on ear Easier to attach and remove device

Considerable improvement in being discreet


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Questions?

Documents

Project31 Presentation