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Baby Sleep Position Monitoring Device

Baby Sleep Position Monitoring Device. Team #13 Nicholas Yap & Koon Seng Chia ECE 445. Outline. Overview Project Design Project Build & Functional Tests Overall Verification Successes & Challenges Ethical issues Recommendations Summary. Overview. Introduction.

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Baby Sleep Position Monitoring Device

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  1. Baby Sleep Position Monitoring Device Team #13 Nicholas Yap & Koon SengChia ECE 445

  2. Outline • Overview • Project Design • Project Build & Functional Tests • Overall Verification • Successes & Challenges • Ethical issues • Recommendations • Summary

  3. Overview

  4. Introduction • Sleeping in the prone sleep position triples the risk of SIDS • Sudden Infant Death Syndrome (SIDS) Upright Prone

  5. Objective • To create a device that monitors the sleep position of the baby in a crib and corrects it if needed. • Warn the parents if our device fails to turn the baby over

  6. Features • Accelerometer to keep track of baby sleep position • Force Sensitive Resistors to keep track of position of the baby on the bed • Automated, safe and simple “baby turning” system using a piece of cloth and two motorized rollers • An alarm to alert parents should our device fails

  7. Video Demo

  8. Project Design

  9. Project Design

  10. Project Build &Functional Tests

  11. Components on baby • ADXL 322 • Microchip PIC16F877A • Linx TXM-900-HP3

  12. ADXL 322 Accelerometer • Used to detect baby’s sleeping position • Analog voltage output for each axis • Varies depending on how the axis is oriented relative to gravity

  13. Test Results for ADXL 322 • X-axis initially aligned with gravity • Rotated clockwise and anticlockwise Output voltage increased as we rotated the accelerometer from +g to -g

  14. PIC16F877A Micro-controller • Converts analog voltage from accelerometer into a digital signal using built-in ADC module • Checks for prone position when upright and vice versa • Reads from accelerometer every second No Upright Prone Prone Position? Yes Yes Upright Position? No

  15. Useful Values • Upright: V<=1.5V 45o 45o • Prone: • V>=1.94V GROUND 45o 45o GROUND

  16. Transmitter and Receiver • Used to transmit a digital signal representing the baby’s sleeping position from the micro-controller on the baby to the micro-controller on the crib

  17. Test Results for TX/RX • Connected transmitter to a function generator • Set function generator to generate square waves of varying duty cycles to simulate digital data

  18. Transmitted Data • “Prone” sleeping position – Transmit “1” • “Upright” sleeping position – Transmit “0”

  19. Components on crib • Linx RXM-900-HP3 • Microchip PIC16F877A • Buzzer • Force Sensitive Resistors • HiTEC HS-7954SH

  20. Force Sensitive Resistors • Used to determine position of baby on the crib • Variable resistor • Resistance changes with force applied

  21. Tests Results for Force Sensitive Resistors Voltage Across FSR Increasing Force applied • Resting Resistance of about 1MΩ • Resistance decreases with increasing force

  22. Setup of Force Sensitive Resistors • Voltage Divider • 4 placed side by side in the bedding Crib FSR 1 FSR 2 FSR 3 FSR 4

  23. Algorithm for Baby Bed Position Sensor • Not present: A<X, B<X,C<X,D<X ; X:noise threshold • Left: (A+B)>=(C+D) • Right/Centre: (A+B)<(C+D) FSR 2 FSR 1 FSR 3 FSR 4 • A B C D

  24. Sleep Position Correction System • Two motorized rollers with a cloth attached in between • Turns baby over by raising one side while keeping the other side stationary

  25. Tests Results for HiTEC Servo Motors • Signal Characteristics: • 20ms period square wave • Amplitude: 3 to 5 V • Vary duty cycle to control speed and turn direction

  26. PIC16F877A Micro-controller • Checks for: • Maximum safe height to raise the sheet to • Sleeping position of the baby • Bed position of the baby • Controls: • Which motor to operate • Alarm system

  27. Alarm System • A simple buzzer that can be used in conjunction with existing baby monitoring devices • Loudness increases with increasing voltage

  28. Overall Verification

  29. Overall Verification • Input Test • Required behaviors of entire system • Refer to page 4 of handout

  30. Overall Verification • Performance Requirements • Maximum device temperature ≤ 95F • Detect prone sleeping position within 2 s • Corrective action completed within 40 s • Motorized rollers must be able to lift up to 40lbs

  31. Overall Verification • Tolerance Analysis 45o 45o GROUND 45o 45o GROUND

  32. Successes & Challenges

  33. Challenges • Serial communication between PICs • Transmit baby sleep position every second • Noisy output voltage from voltage regulator • Added capacitor across output pin and ground • Motor speed calibration • Trial and error with lots of patience

  34. Successes • Generally on schedule • Overcame all challenges • Consulted and updated TA regularly • Safe and simple “baby turning” system

  35. Ethical Issues

  36. Ethical Issues • Protect baby from electric shocks and overheating • Possible risks in using the device • Thorough system testing • Honest performance figures

  37. Recommendations

  38. Recommendations • Low battery alert • Raise opposite side of sheet to enhance turning safety • Reduce size of baby box by using: • 8-pin micro-controller • Low power transmitter • Surface mount components • Smaller batteries • Can pin device to clothes if small enough

  39. Summary • Overview • Project Design • Project Build & Functional Tests • Overall Verification • Successes & Challenges • Ethical issues • Recommendations

  40. Questions & Answers

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