(Acknowledgement: This project was inspired and made possible by the MPGuino.)
As part of an extensive research project in optimal control, we have developed a sensor suite that we think can be used to map the engine efficiency of YOUR particular car. The engine efficiency is derived from logging data under normal driving conditions for any individual car. In fact, engine efficiency is probably a misnomer, as we are actually calculating complete system efficiency, including drivetrain losses, etc...
While similar to the MPGuino, this project has some notable differences: 1) no screen, 2) GPS logging, 3) accelerometer, and 4) saving data to an SD card.
The principle and application is described in short here:
http://www.eissq.com/ponthy/preprint.pdf (I had to resort to the obscuring the HTML because of the anti-spam features. I'll delete them as soon as the website says I have enough posts to have the right to post links.[Thanks MetroMPG for fixing it.])
As indicated in the above pdf, the solution is comprised of two parts: a hardware logger (shortly described above, with more details later) and a software package based on an Extended Kalman Filter.
The software package is complete, and is more or less in fire-and-forget state. It’s in alpha because documentation is lacking and it would take a few back-and-forths with me to properly set up your Matlab environment.
The software outputs the engine fuel efficiency, and gives you some other nifty outputs, such as the included Google Earth trip tracking (where color indicates speed).
I have full hardware schematics available, and will distribute the originals on demand. I am providing the jpgs for those curious.
In continuing this research, I would like to extend this project to cars outside the few we are already following. We are looking for people who would like to help us out. We are giving away the Eagle schematic and AVR code base in hopes that some of you will be motivated to build your own, with technical assistance from us. In theory, anyone can build one of these, although in reality the two SMC components (ATMega chip and accelerometer chip) are much easier with an oven. The overall parts cost, not including the GPS and board, can be brought in at well under $20. The GPS can be anything that can output NMEA sentences over a serial port. (I use a FV-M8 at 5Hz.)
As of this moment, I have ~10 circuit boards that are completed and tested, and another two for an upgraded model that awaits soldering. I will give these away for free to anyone interested in installing these units. I will include the AVR, the accelerometer, and the SD Card adaptor, as these might be hard to find. The rest are OTS components: resistors, capacitors, etc… I ask only that people pay shipping.
I also have a new version already written and debugged for the XMEGA, which solves some of the limitations of earlier models. It simply remains to finish the circuit schematic and fabricate the boards. If someone were to complete the circuit schematic for the XMEGA, I would be able to run off 10 or so boards, and then distribute them for free.
This could also be ported to the Primer2 or STM8S-Discovery platforms, if someone were so inclined. Thus you have the convenience of the MPGuino with the power of the Kalman Filter. I can offer a bit of assistance on these projects, but not as much as for the Primer2.
For those of you who have a CAN bus, I also have code for a $75 CAN reader, one where you have nothing to solder but one single 8-pin chip.
If it happens that any of you are in Luxembourg, Luxembourg or Auxerre, France, then I can give you a free working model and help you install it.
If anyone in the community is interested in the programming side of this project, the biggest help would come from converting some of the matlab files into C, Python, or some other language that can run on anyone's computer, without having a multi-thousand dollar software license.
I am interested in any and all comments that can help us improve this. (Notably, I am struggling to explain why I get a fuel efficiency that is globally too high, even if the shape of the curve seems to be spot-on. Which in the end is all that is important, as relative efficiency between engines and engine operating points is far more useful than absolute efficiency.)
As I get an idea of the community and internet’s reaction to this project, I will make a website that explains it a bit better. I admit that this post is a bit disorganized, but alas such is the limitation of forums. Unfortunately, as a result of having spent years on this project, I suffer from being too close to the problem and thus am likely assuming that things are clear when they are anything but. Don't be shy, let us know what you're thinking!