Vehicle Monitoring ECE 445 Senior Design Project System

Vehicle Monitoring ECE 445: Senior Design Project System 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 UART Accelerometer Interrupt 2 Gyro Interrupt 2 MUX Select Bits Gyro/Accelerometer Battery Voltage Battery Temperature Battery Charge On/Off Gyro Interrupt 1 Accelerometer Interrupt 2 Debug LEDs

UART Atmega 328 has only 1 UART port Problem: • Wi-Fi, OBD, and GPS use UART • Used ISL 54216 UART Multiplexer • 2 Control Pins • • ISL 54216

OBD • • • OBD-II protocols include CAN, J 1850 and ISO STN 1110 by Scan. Tool 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 = 10 kΩ C = 1 u. F Yields 3 d. B cutoff of 16 Hz R C

Power

Power System

Power Conversion schematic

Design Choices • • • Used a buck converter for 12 V-5 V conversion Linear regulators for conversion to 3. 3 V and 1. 8 V Used datasheet to determine inductance of buck converter Total current consumption < 0. 8 A Made 330 u. H inductor

12 V to 5 V Conversion Output ripple voltage less than 500 m. V

Battery Chargi ng 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 3600 m. Ah lithium ion battery Max battery voltage = 4. 2 V When car is off, Atmega: 15. 5 m. A (awake mode) GPS: 31 m. A (tracking mode) Wifi: 80 m. A (operating current) Total consumption: 126. 5 m. A Discharges at 0. 035 C Lasts for 28. 4 hours

Software

Objectives • • Read data from: – Accelerometer – Gyroscope – OBD Transmit data to online server over Wi. Fi Store data in online server Retrieve data on demand

Architecture

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

I 2 C Communication • Microcontroller works as master to slave ICs • Protocol • Send start bit • Set I 2 C 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: 54. 86. 75. 167 Content-Type: application/json {"data": 123} GET /vms/data HTTP/1. 1 Host: 54. 86. 75. 167

Access Webpage

Challenges/Improve ments • Challenges • CC 3200 microcontroller couldn’t be flashed • GPS module wouldn’t communicate • Multiplexer got shorted to 12 V • 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?