Vehicle Monitoring System ECE 445: Senior Design Project Ishan Ahuja Caleb Perkinson Samuel Utomi May 2, 2016

Introduction Auto insurance providers have no accurate way to gauge risky driving behaviors. This leads to inflated insurance rates for safe drivers. Goal: Create a vehicle monitoring system to record live data about driver behavior to accurately judge safe driving ability.

Objective We intend to create a prototype driver monitoring system which can show a data based snapshot of a driver's abilities. Our system will: Monitor and save driving records through the OBDII port on the consumer vehicle. Allow for access to data through simple online portal. Measure risky behaviors such as fast acceleration and quick turns based on adjustable thresholds.

Block Diagram

Hardware

Objectives -Detect poor driving behavior -Monitor car status through OBD port -Know car’s location in case of theft, etc. -Plug-and-Play

Microcontroller Gyro/Accelerometer Battery Voltage Battery Temperature Battery Charge On/Off Gyro Interrupt 1 Accelerometer Interrupt 2 Debug LEDs UART Accelerometer Interrupt 2 Gyro Interrupt 2 MUX Select Bits

UART Atmega328 has only 1 UART port Problem: Wi-Fi, OBD, and GPS use UART Used ISL54216 UART Multiplexer 2 Control Pins ISL54216

OBD OBD-II protocols include CAN, J1850 and ISO STN1110 by ScanTool converts these messages into UART Works with simple AT commands to talk with car CAN Transceiver

Layout

Filter Simple Anti-aliasing filter Cutoff Frequency: R = 10kΩ C = 1uF Yields 3dB cutoff of 16Hz R C

Power

Power System

Power Conversion schematic

Design Choices Used a buck converter for 12V-5V conversion Linear regulators for conversion to 3.3V and 1.8V Used datasheet to determine inductance of buck converter Total current consumption < 0.8A Made 330uH inductor

12V to 5V Conversion Output ripple voltage less than 500mV

Battery Charging Circuit

Design Considerations Wanted constant voltage on the source side of the MOSFET Using just NMOS to control meant unstable conditions Decided on using combination of PMOS and NMOS Resistor divider to lower voltage of MCU ADC input Low pass filter to measure battery voltage Low pass filter to measure battery temperature

Thermistor Circuit

Battery Life Using 3600mAh lithium ion battery Max battery voltage = 4.2V When car is off, Atmega: 15.5mA (awake mode) GPS: 31mA(tracking mode) Wifi: 80mA(operating current) Total consumption: 126.5mA Discharges at 0.035C Lasts for 28.4 hours

Software

Objectives Read data from: –Accelerometer –Gyroscope –OBD Transmit data to online server over WiFi Store data in online server Retrieve data on demand

Architecture

UART Communication Used to communicate with OBD and WiFi Required a multiplexer Could only communicate with one device at a time Devices responds with data to input strings AT commands for WiFi module Parameter IDs for OBD Issues Asynchronous – long wait times Unique transmissions speeds Bus must be stopped and restarted

I2C Communication Microcontroller works as master to slave ICs Protocol Send start bit Set I2C slave address Send internal register to set Send register for relevant reading Read data from correct register Decipher data in code Very user-friendly Requires only two lines (Clock and Data)

Code Structure

RESTful Web Service Can receive and send data over HTTP requests APIs stored on Amazon Web Services Receive and store JSON formatted speed data Return all speed data as JSON Return last speed data as JSON Increment/reset/return gyroscope high counter Increment/reset/return accelerometer high counter Data stored in static data structures Hash map for speed data Static integers for counters

Sample POST/GET Request POST /vms/data HTTP/1.1 Host: Content-Type: application/json {"data": 123} GET /vms/data HTTP/1.1 Host:

Access Webpage

Challenges/Improvements Challenges CC3200 microcontroller couldn’t be flashed GPS module wouldn’t communicate Multiplexer got shorted to 12V Improvements Low power mode UI improvements More OBD data points Support for multiple vehicles

Conclusion Can operate on car battery with rechargeable Li-Ion cell Simple Web UI with dynamic updating Functional OBD interface Able to send acceleration alerts from using Gyroscope and Accelerometer

Credits Cara Yang Prof. Tomas Galvin Leung Student Venture Fund

Questions?