Mid-Semester Presentation

Senior Design I

February 24, 2011

Child Safer Seat

Child Safer Seat Team

Dr. Raymond WintonAcademic adviser

Blake Bennett EE

ProgrammingTechnical

Documentation

Ayman Busaad

EEHardware

Implementation

Hardware Design

Chris Howell EE

Hardware DevelopmentTechnical

Documentation

Kenneth Gustine

EEProgramming

Website design

• Problem

• Solution

• Block Diagram

• Constraints-Technical-Practical

• Trade-off

• Progress

• Timeline

• Questions

Outline

The interior temperature of a car can rise by 20°F within only ten minutes which can cause a child death due to hyperthermia. [1]

Before airbags, 1990 – 1992: 11 deaths due to hyperthermia [1]

After airbags, 2006 – 2009: 108 deaths due to hyperthermia [1]

Problem

Combined a device with a car child seat which can determines when a child is in danger due to extreme temperatures and alerts help if a situation becomes hazardous.The device can alert via text messaging (SMS) to a

number that is programmed into the device.

Solution

Block Diagram

Thermo Sensor

Processor

Power Supply

PressureSensor

Antenna

Technical ConstraintsName Description

Compatibility Device must be compatible with standard cellular networks.

Weight SensingDevice must be capable of detecting the presence of a child weighing at least five pounds in a safety seat.

Temperature SensingDevice must measure ambient temperatures from 30° to 100° Fahrenheit.

Temperature Operation Device must operate from 0° to 180° Fahrenheit.

Battery LifeDevice must have a minimum battery life of three months under normal operating conditions.

Practical Constraints

Type Name Description

Sustainability Maintainability Battery replacement or recharging must be a convenient,intuitive process.

Manufacturability Personalization Device must be programmable with multiple user phonenumbers.

Battery replacement or recharging must be a convenient, intuitive process

Sustainability: Maintainability

Device must be programmable with multiple user phone numbers.

Manufacturability: Personalization

Cellular Network Trade-off

Service Network Price Setup Providers Coverage Storage

GSM Lowest Easy Many Plentiful SIM card

CDMA Medium Complex Many Plentiful None

GSM Trade-OffManufacturer Model Advantages Disadvantages

Telit GC864 PYTHON, ADC/DAC, Price No breakout boardNo antenna connector

Siemens GSM/GPRS modem MD720-3

Everything set up Very Expensive

Telit GE865-QUAD PYTHON, antenna connector, ADC/DAC, Price, breakout board

No on board SIM

Telit GM862-QUAD PYTHON, GPS, on board SIM and antenna connector

 Very Expensive

Force Sensitive ResistorAdvantage: Can be easily integrated into child seatDisadvantage: Analog signal transmitted to system

Snap-action Pushbutton SwitchAdvantage: Binary signal transmitted to systemDisadvantage: Maybe difficult to integrate into car seat

Pressure Sensor Trade-Off

Options Advantage Disadvantage

AA batteries •Ease of replacement•Low initial cost

•Ongoing battery cost

Battery Pack •Low maintenance cost•Manufacturer controls battery type

•Higher initial cost•Charging inconvenience

Vehicle Power Supply •No batteries•Smaller device

•Inconvenient to user•External wires•Power stops with removal of keys

Power Source Trade-offs

Temp Sensor Trade-off

Options Disadvantages Advantages

Digital •Higher power consumption

• Easy to Sample• More Accurate• Output less susceptible to Noise

Analog • Less Accurate• Noise susceptibility

• Lower power consumption• Precision only dependent on microcontroller’s ADC

GSM module : Telit GE865 Received, on boardTemp sensor: LM60 Received, on boardAntenna: Received, on boardSIM card holder: Received, on boardPressure sensor: ResearchingPower Supply: Researching

Progress

Progress cont.

Timeline

Time line January Febuary March April

Research

Hardware Testing

Programming

Prototype Testing

Optimizing

[1] J. Null. (2011, January 17) Hyperthermia Deaths of Children in Vehicles. [Online]. Available: http://ggweather.com/heat/

References

Questions