Smart Car Seat GT Design Expo Spring 2017 / Mbed 2 deprecated Smart_Car_Seat_v1

This is the first version of the mbed program for the Smart Car Seat developed by the Smart Car Seat Team of GaTech Design Expo Spring 2017.

Dependencies:   Adafruit_FONA FSR SDFileSystem mbed

Fork of Smart_Car_Seat_v1 by Jea Du Kim

Team Members

Bryan Bates – OBD/Bluetooth System
Robert Dunkin – Physical Wiring/Power
Jgenisius Harris – Cooling System
Jea Du Kim – Sensor System
Emily Pitts – Smartphone Application
Tyler Woei-A-Sack – GSM Communications

Advisor

Dr. Mick West

Overview

The purpose of this project was to design a child’s safety car seat with Internet of Things capabilities and a cooling system that activates in the case of an emergency. It is comprised of a network of sensors, a wireless notification system, and a cooling system.

How Does It Work

The Smart Car Seat is initially set up using a smartphone application where the user inputs their phone number. The number is saved to an SD card and is read by the GSM module when it sends the text messages. If the infrared thermometers read a critical temperature and the force sensitive resistors detect someone, the cooling system will turn on and a text message will be sent to the phone number on file.

Smart Car Seat Program

Components

This project involves the usage of the mbed LPC1768.

Force Sensitive Resistors

This project uses 4 Square FSR Interlink 406, two placed on the seat and two placed on the back rest to detect if someone is sitting on the seat.

As they are still resistors, the orientation of the pins do not matter, as long as one end goes into VCC and the other leads to a voltage divider and an AnalogIn like shown in the diagram. With a 10K Ohm voltage divider, a raw analog value of 0.5 for each FSR should be enough to distiguish an object of the size of a small child on the sensor.

Any additional information can be found at the Force Sensitive Resistors page.

MLX90614 IR Thermometers

This project uses two MLX90614 IR Thermometer placed on the back of the headrest to measure the temperature of the child sitting on the seat and the ambient temperature.

At around room temperature, the Thermometers should read approximately 22 C. When reading the temperature from the palm, the sensors should read approximately between 30 and 35 C.

With the MLX90614 and I2C, you can run up to 127 thermometers through the same SCL and SDA connection as long as they have different 7-bit addresses. The default I2C address for the MLX90614 is 0x5A, but it can be changed with this program.

Any additional information can be found at the MLX90614 I2C IR Thermometer page.

SD Card File System

This project uses the basic SD Card reader that works with the mbed to store all the contact information for the system.

Any additional information can be found at the SD Card File System page.

GSM Module

This project used the FONA 808 MiniGSM provided from Adafruit to send messages to the contact information stored in the SD Card.

Both the 800 and the 808 uses the same protocols, so any additional documentations, information, and project libraries can be found at the Adafruit FONA 800 Project page.

Bluetooth Module

This project uses the HC-05 Bluetooth Module to connect with an Android app to update or change contact information stored in the SD Card.

The Bluetooth module simple acts as a wireless Serial connection, so there is no need for additional Libraries other than the Serial.

Any additional information about Serial connections can be found at the Serial page.

Cooling System

The Cooling System involves the use of a MOSFET Relay and a combination of 5V Fans, Peltier Plates, and Heatsinks to provide cold air when commanded to.

Any additional information about Relays can be found here.

diff -r 5a4b2c91de63 -r a33e55fecf16 main.cpp
--- a/main.cpp	Wed May 03 21:14:11 2017 +0000
+++ b/main.cpp	Wed May 03 23:03:22 2017 +0000
@@ -129,6 +129,7 @@
             }
             if (danger) {       //When child is in "danger"
                 fona.sendSMS(pnum, message);    //FONA will send message to the contact
+                wait(1);        //Adjust wait time after sending a message
             }
         } else {
             led3 = 0;
@@ -136,7 +137,7 @@
             CtrlRelay = 0;      //When child is no longer on the seat
             danger = false;     //The system resets
         }
-        wait(1);
+        wait(1);        //Adjust wait time after reading
     }
 }