Hello, I’m looking for a GPS receiver for a racecar. You maybe heard of Formula Student or FSAE. The racetracks we are driving on, are about 3m wide an have partially very small turns with a 6m radius.
So I think it should be a 10Hz receiver.
Unfortunately I have no experience with modules like you are offering. Because of that I have a few questions about it.
What do I need besides the GPS module to work with the chip. Do I need an evaluation board?
How is the GPS-information provided by the module? Is the information always been output like written in the GPS buying guide in ASCII characters?
We have a CAN-Bus implemented in our car, so it would be great to get the Information over CAN. Is that possible to get somethink like that or do I have to design a GPS-to-CAN board by myself?
Last question: some GPS receivers for cars do provide information about acceleration in x- and y-direction and additionally yaw-rate. Do you have receivers which are able to do that, too?
I hope I could give you a good summary what I need. If you have any questions about our project, I would like to answer it.
I also made some experiment with an EB85A module on my trackbike. If you want to analyse driver’s performance, these GPS modules are not precise enough. Passing ten times on the same point will give you different path.
GPS is good to locate data or events on the track. It is very helpfull when your software can draw track map and classic data view. Take a look at these sites http://www.motec.com or http://www.race-technology.com/
thanks for your fast reply. I already talked with the guys of motec and race-technology. They have great systems for my problem, but they are not affordable for us or don’t fit in our system.
I also reviewed solutions of AIM and 2D-Datarecording. There are the same problems.
So this is the reason why I’m looking for a selfmade solution.
Is the EB85A the most precise module on sparkfun.com or is there something better? I’m new to this problem, so I can’t overview all modules with its facts and options.
I would suggest to go with either EB85 or LS20031. They are widely used and you will find lot of exemples to connect it to a microcontroller.
New version of LS20031 is 10Hz, but Sparkfun doesn’t have it in stock yet. LS20031 is also simpler to connect and have battery already on pcb. This would avoid coldstart, which is much longer, about 45 seconds, than hotstart which is about 3s.
A good module will be: GPS unit connected to a microcontroller containing a CAN interface. Add a switched output to any lap timer to replace magnetic or optical sensor. GPS coordinates handling need double precision floats. It is better to use an 32 bit micro. I used a LPC2148 to make a lap timer with graphic LCD. For your application, LPC2129 or LPC2194 would be a good choice.
If I remember correctly, the FSAE competition is just an autocross right? You don’t need any sort of real time lap timer or anything, correct? So you can probably get a long way with simply logging your runs and doing a post-analysis of the data. So this breaks the project down into two parts, recording the data, and analyzing it later. This is the approach I’ve taken with a personal project of mine. I’ll give what insight I have.
First, let me suggest a commercial product, MaxQData.com. They’ve got several levels of products, and you’d be lucky if you could make something half as useful. I would say that it’s by far the most “standard” tool of this type. And if your pinched for time, buy one of these and be done with it.
As for doing it yourself… Obviously you’ll want a GPS sensor, with at minimum a 5hz update rate. Also an accelerometer might be useful for measuring cornering forces, braking, etc. You probably won’t see any g-forces higher than +/-1.5g, so a 2 or 3g sensor would be adequate.
A couple of options for logging the sensor data:
Get a netbook and a bluetooth GPS unit. I have a GlobalTop G33 unit, it has a 5hz update rate, and an Acer Aspire One netbook. In my miata the netbook fits perfectly into the glove box, but I imagine you could make a pocket to stick it in? And then tape the bluetooth GPS to the roll bar or something. Make sure the netbook has an SSD hard drive, so it can survive the vibration. Then write a simple program for receiving the NMEA text via bluetooth, and logging it to a file. This is a fairly trivial program to write.
The second option is to create some hardware to do it. A micro-controller hooked up to a GPS module, and an SD-Card adapter would get you a long way. Logging information from other sensors could also be done. Accelerometer, maybe something for monitoring RPM, etc.
So that’s the easy part. Analysis of the data is really the difficult part. Plotting the GPS coordinates, and graphing the other sensor information, acceleration, velocity, etc. To my knowledge, there’s no free software available that does this. But, it can be an extremely useful tool for autocross, but its a big project in an of itself. My suggestion would be if your not interested in buying a ready-made unit, that you should contact someone in the computer / software engineering department at your school and seeing if you can get them to help. It would make for a great capstone project.
As to the accuracy of a GPS unit. I have no idea, you’ll have to do your own testing.