Here's a couple more examples of what kind of data you can get with this device:
1) Individual wheel speeds
Here's a launch in the beginning of a run, followed by a couple of corners at a recent autoX:
Front left: cyan blue (25 Hz)
Front right: purple (25 Hz)
Rear left: green (25 Hz)
Rear right: orange (25 Hz)
You can see in the beginning the rear wheels spinning at roughly constant rate, whereas the front wheels speed up with the "real" speed of the car. If you look closely, you can see the slope of the graph for the front wheels increases slightly as the car's own speed approaches the speed at which the rear wheels are spinning (or, in other words, as the rear wheels spin less relative to the speed of the car they generate slightly more traction).
At t = 2025 you can see the rear left wheel starting to slip in a left corner until the LSD engages.
At t = 2026 ... 2030 you can see how a slalom looks like.
At t = 2033 you can see the fronts locking up as I brake on a bumpy patch of the track.
2) Combined acceleration vs pedals
Accelerator: green (25 Hz)
Brake: orange (50 Hz)
Combined acceleration, from the CAN bus: purple (25 Hz)
Combined acceleration, from GPS: cyan (10 Hz)
I was looking at how well (or not well) I trail brake on a ~55 mph straight into a ~25 mph hairpin.
As you can see, the accelerometer data on the CAN bus is pretty noisy.
This is typical for digital accelerometers, and usually some filtering is needed.
Also you can see the GPS data is slightly offset/delayed.
Both of these issues are fixable, see
this discussion on the RaceChrono forum.
Even without filtering IMO the data from the CAN bus is more useful than the 10 Hz data from the GPS.
For example, right before braking I know I was going in a straight line at the rev limiter, so should be ~0 G's.
Indeed, I see a brief drop to 0 in the data from the CAN bus. For comparison, the minimal value in the GPS data here is 0.5 G's!
The CAN-based "combined acceleration" graph jumps up quickly as I step on the brake pedal;
whereas the graph based on the GPS data takes ~0.5 sec to get from the minimal value to the first local maximum.