Vehicle Telemetry Platform
Ever wondered what goes on under the hood of your car? Wish you could
peek inside the engine management system and read values from it?
Annoyed that your dashboard displays a cryptic "Check Engine" light
(yep, the engine is still there) but gives absolutely no explanation
what the problem might be?
You don't need a US$10,000 diagnostic console or even a laptop
computer to get access to useful data from your car. With this project
you can connect an Arduino to the engine management system in your car
and log data to a CSV file on a USB memory stick in real time as you
drive around. By reading and storing engine management system data and
combining it with the GPS location you can create your very own "black
box" flight data recorder for your car to record a complete snapshot of
all engine
management parameters at the moment a fault occurs or generate graphs of vehicle performance
.
Because this project stores everything in a standard CSV file on a
memory stick with a normal FAT filesystem it's really easy to load up
the data on your computer and manipulate it in any way you like. When
you get home from a trip you can pull out the memory stick, plug it into
a computer, and open it in a spreadsheet or convert it into other
formats.
Included in this
project is a simple script that converts the raw data into KML, the
Google Earth data format, allowing you to create an interactive 3D
"fly-around" view of a trip. The screenshot below was generated using
Google Earth and shows the vehicle speed plotted as the height of the
line. You can clearly see the speed of the car varying as it goes around
corners and through intersections.
You can also process
the data to generate graphs like the one below that shows vehicle data
plotted using Google Charts, and you can clearly see the coolant
gradually warming up as the car starts from rest; the accelerating and
decelerating during the trip; and finally coming to a halt at its
destination. The engine RPM at each part of the trip is also plotted and
you can see how it interacts with vehicle speed.
Extracting data
from a vehicle's engine management system may seem like magic but in
recent years it has become much easier thanks to a vehicle interface
standard called OBD-II, or On-Board Diagnostics version 2. All
cars and light trucks sold in the US since 1996 have been required by
law to provide an OBD-II interface that provides access to a variety of
operational data about the vehicle. Europe followed in 2001 for petrol
vehicles and 2003/4 for diesels with the "EOBD" (European OBD) standard
which is basically just OBD-II with a different name.
Because car manufacturers try to standardize their production lines,
OBD-II vehicles also found their way into many markets outside the US
from 1996 onwards. Most Japanese car manufacturers, in particular,
deployed OBD-II in other markets very rapidly even when not legally
required to do so. The result is that when you take your car to an auto
mechanic the first thing they usually do is plug in either a dedicated
diagnostic console or a laptop using a special adapter, then run
software that interrogates the engine management system to retrieve
stored data such as a list of faults it has detected since the last
service.
In this project we combine an Arduino with an OBD-II adapter, a GPS
module, and a USB host module to create a flexible platform for
extracting, logging, and reporting on data from your car. You won't get
Formula-1 style telemetry with thousands of samples per second, but
you'll certainly get more information than an annoying "check engine"
light!
