IEEE Spectrum April, 2009 - 15

computing.com) made it a
snap to access the computer's
audio-recording hardware.
Still, I spent a long weekend
getting the rest of the code
written-including such
niceties as a screen for
viewing the raw signals and
two simulated dashboard
gauges for instantaneous
mpg and revolutions per
minute [opposite page].
It worked great, except
for a couple of complications
I hadn't counted on. The
computer I used took forever
to boot-so much for hopping
in the car and darting off.
Also, there was no good place
to position the bulky laptop.
So while the performance
was good and the price was
right, this strategy ultimately
proved impractical.
I thus decided to replace
the laptop with an opensource fuel-economy
computer called MPGuino.
This gadget is based on the
Arduino microcontroller
and is available in kit form
for less than $40 from Spiff's
Electronics Notebook.
Assembling the MPGuino
was a quick job, and having
already located the VSS and
injector signals, the biggest
challenge (as with many
such do-it-yourself projects)
was fashioning a suitable
enclosure. I ended up with
a RadioShack project box,
which I mounted in front
on the car's used-only-for-

loose-screws ashtray. The
calibration values listed for
my model on the MPGuino
wiki (at EcoModder.com)
turned out to be spot-on, so
setup wasn't difficult.
This little "carputer"
has opened my eyes to
how my car uses gas and
what I can do to limit the
burn rate. I've learned, for
example, that idling while
stopped really does waste
a significant amount of
fuel-it's outright painful
to watch your trip-averaged
mpg tick downward while
waiting for a red light to
change. On the other hand,
sprightly acceleration burns
less fuel than I'd expected,
and it's great to watch the
instantaneous-mpg numbers
shoot up as you disengage
the clutch, lift your foot off
the gas pedal, and coast. But
leaving the car in gear to
decelerate is often a good
conservation strategy, as it
can put the engine in fuelcutoff mode, which the
MPGuino shows.
I plan to hone my
ecodriving skills with this
electronic aid. Perhaps by
this July, my 12-year-old,
three-cylinder Geo will
be challenging my town's
many Priuses for bragging
rights. In any event, I'll
be ready if gasoline prices
again climb to levels that
make your ears pop.
-David Schneider

ECU pin-out diagrams:
http://innovatemotorsports.com/resources/ecu_pinout.php
FreeView Sound Software:
http://technical-computing.com/freeviewsound.htm
Arduino microcontroller: http://arduino.cc
Spiff's Electronics Notebook: http://spiffie.org/electronics
MPGuino wiki: http://ecomodder.com/wiki/index.php/MPGuino
www.spectrum.ieee.org

Maplesoft
Maple 12, MapleSim

tools & toys
new mAth

SolidWorks, allowing
an engineer to optimize
major updates from a design in Maple and
maplesoft, wolfram, then send data back to the
Design science,
CAD program.
and tera Analysis
The new Exploration
present engineers
Assistant lets a user vary a
parameter in an equation
with a calculatory
or graph and see the
cornucopia
results. And inexperienced
he venerable math
Maple users now have
programs Maple
new templates that take
and Mathematica
common commands.
long ago outgrew pure math
Mathematica has had many
to include numerical and
of these features for some
symbolic math, graphics,
time. It's great to see that
document preparation,
competition between the
and more. Maplesoft and
two companies is easing the
Wolfram have each recently
learning curve users faced
released a major update-
on earlier releases.
Maple 12 and Mathematica 7-
The new MapleSim is an
and Maple has a new
elegant product that runs
simulation package as
in parallel with Maple 12.
well. The company is
With a few mouse clicks,
increasingly pitching to
you can create, say,
engineers-an approach that
a model of a circuit, or
has long been successful for
a thermal or mechanical
another big math program,
system, and the program
MathWorks' Matlab.
will transparently call
For example, Maple's
on Maple 12 to show
new Dynamical Systems
how it performs. Models
package helps users study
the behavior of discrete and
continuous time systems,
central to many signalprocessing and control
applications. Maple can now
communicate with the two
leading computer-aided
design packages,
Autodesk
Wolfram
Inventor and
Mathematica 7

T

April 2009 * iEEE SpEctrum * NA

21
http://www.computing.com http://www.EcoModder.com http://www.innovatemotorsports.com/resources/ecu_pinout.php http://www.technical-computing.com/freeviewsound.htm http://www.arduino.cc http://www.spiffie.org/electronics http://www.ecomodder.com/wiki/index.php/MPGuino http://www.spectrum.ieee.org
Table of Contents for the Digital Edition of IEEE Spectrum April, 2009
