I am in the process of building a hardware datalogging device to run with racechrono, the first version (almost complete and ready for testing) has the following:-
X + Y axis Accelemeters built in.
5 Channel Analogue inputs (for water temp, oil temp, throttle, oil press etc)
1 Digital Input for Engine RPM
It will send data via its builtin bluetooth. I will also make one with a 5hz GPS sensor built in.
These will be available to buy when ready, hopefully within 6weeks.
Please add any comments and suggestions here so i can consider and build it into the product.
Yes, the whole idea is to connect up your existing sensors, oil temp, water temp, RPM etc etc, it will accept 12v inputs no problem.
The sample rates i need to decide on, the accelerometer and rpm ones will be 5hz, or could be 10hz if needed, and for the analogues 1hz is probably enough, again not really a limit on sample rate, if you max'd out a serial interface, you would be getting a LOT of data to look at.
Wheel speed may not be that easy as they are probably car specific, never really looked at the output from one, will plug it into my car at somepoint and see what it looks like and if it can be added.
logging to memory card module can be added on at a later time, as is an RS232 input, it will have the hardware for that, but it wont be enabled in the first versions!
aol: i have a working example here outputing in race technology serial format, can you add it into racechrono to log/show accelometer values and the analogue inputs (any any other future ones) I could alternatively change it to output the ODB-II protocol (if documented) but i dont have any experiance in that, it doesnt seem as flexible as the race tech one.
Let's just use the DL-1 format. Nice to have support for DL-1's too. OBD-II protocol is a two-way protocol so it can't be used output only. I have some binary examples of DL-1 output so I will use those to write the support for it. First I will add support for the GPS, later accelerometers and analogue channels. Currently I'm working on the architectural changes to allow other input than NMEA, and very soon I can start writing a decoder for the DL-1 format... Hopefully that goes without problems.
Have you calculated for how much you could sell these units for? Please email me if you have specific questions about development etc.
http://www.xtracing.com/en/gpxpro/index.php - CHEAPEST with all features but no export yet
http://www.racepak.com/IQ3Dash.php - Nicest unit
Question is still how much and are you in EU or US for distribution purposes?
Probably the most important input
Wheel speed; a certain number of pulses per wheel revolution
Allows you to work out % slip under braking and acceleration.
Brake pressure; 10Hz; resistive sensor
You can see how smooth you're being and how quickly you're getting to the threshold.
Throttle position; 10Hz; resistive sensor
Not sure I need to annotate this!
Steering angle; 10Hz; resistive sensor
Again, you can see how smooth you're being and deduce understeer/oversteer.
Damper displacement (x4); 100Hz; resistive sensors
You can see aero performance and damping performance. You need a very high sample rate though.
Accelerometers (x2-x6); 10Hz; resistive sensors
You can see smoothness (again) and how consistently close to the tyres' limit you are. Not only can you use lateral/longitudinal/vertical G but you can also use gyros to see yaw rate and roll rate.
That's 17 inputs but allows you to do rather a lot.
Most of those data loggers linked by Dmitriy have displays etc. This would need to have only the sensors and the "main unit" to make everything one data stream to send to RaceChrono / storage. No display needed (or wanted), as RaceChrono can handle this side :) So more like the DL-1 mentioned earlier: http://www.race-technology.com/dl1_2_27.html
I wonder how easy it is to do small batch of these cheap enough? I guess its not necessary to mention it needs to be MUCH cheaper than the DL-1? :) Also good point by Dima that it needs to comply with the EU and US directives ( http://en.wikipedia.org/wiki/RoHS comes to my mind first ).
Tipical inputs are, Water Temp, Lap Time and splits (with a magnetic sensor), RPM count. And time of working motor, starts every time that pass for an start line, and stop 5 min after pass the last start line.
So, no one have throttle input or brake input (only needs a potentiometer), no one have temperature tires (will be very nice to see temps of my tires in real time)
Been working on it in the last few days, and I have one here up and running.
aol: i can very easily send you a test device if you need a device to plug into PC serial that just spits out some random data values in the correct (race tec) format.
As for price, target is Â£100, Â£150 if it has 5hz GPS on board, obvioulsy extra inputs, gyros etc and it just keeps going up.
As with everything, depends on qty, if there was a big demand, can get them produced in far east, and the price comes tumbling down.
Maybe i should setup a webshop and start taking pre-orders :-)
There is a c version on there too.
Are you thinking of having the data from this box work in the dl1 software???...that would be a strong sell point.
I've got another 4 rounds of the championship this year and I'm planning to do a good few track days this winter, so I'll get a goodly amount of testing going.
Turns out my device will actually have 6 analogue inputs (20hz) + 2 axis accelerometers (20hz) + optional 5hz GPS
So, you connect up your inputs, rpm, analogue for oil temp, etc etc to this little box, and all it does it convert that info, and adds the built in accel values, to an RS-232 output, in Race Technology Serial Format, which you can connect to anything you want, Race Tech Lite Monitor for example or Race Chrono (once it has some support to display or more importantly (hopefully) log the data, as far as the physical interfacing goes there is 2 options, you can either plug the device straight in to the 9 pin socket directly or use the onboard bluetooth (virtual com port)
so no RPM input after all ?
EDIT : if you could add a 5v and/or 12v output to power sensors that would be fine too
Separate GPS antennae on a 5 foot cord so the unit can sit inside car/bike but the antennae can be on the roof/tail of the bike. I don't like putting expencive electronics where they will get damaged.
I'll email you back with a bigger list.
First unit is coming on nicely, the device is regulated internally and will take pretty much any DC power (within reason will work from about 6v-36v) the A/D inputs will be physically switched at the setup stage with dip swtiches on the device, to either be 0-5v inputs, or 0-15v inputs. You will need to set each of the inputs once to choose which port will use which input voltage.
aol: the prototype unit is ready now and sending out the correct DL-1 format for all the channels that will be used.
I need to tidy up the code a bit, add some error checking and such and then solder it up onto the board once finished. Was hoping to have it done by now, but work is getting in the way and off on holiday next week!
I was doing the accelerometer support in between but unfortunately I'm "stuck" with writer's block, so I decided to start working on the DL-1 support again :-)
Just need to crack the RPM clock speed counting maths, and get it working on a higher baud (works perfectly on 4800 but errors as i wind the speed up) and the first one is ready to go out to the first beta tester!
I have a Track event and a race coming up on August 29-30.