Issue with distance and time

[madmatt]

I have an issue with i2 and the distance/time channels.

I have noticed that my race time and distance was much less than reality.

The following picture shows corrected distance set using "use distance channel":


While the following picture shows corrected distance set using "use speed channel":


As you can see it is not linear, which is strange. When exporting the results, here is a portion where the singularity occurs:

Code: Select all

Time  Distance
255     1233
255.1   1233.7
255.2   1234.4
255.3   1235.1
255.4   1235.8
255.5   1236.5
255.6   1237.2
255.7   1237.9
255.8   1238.6
255.9   1239.3
256     1240
256.1   1285.5
256.2   1331
256.3   1376.5
256.4   1422
256.5   1467.5
256.6   1513
256.7   1558.5
256.8   1604
256.9   1649.5
257     1695
257.1   1695.5
257.2   1696
257.3   1696.5
257.4   1697
257.5   1697.5
257.6   1698
257.7   1698.5
257.8   1699
257.9   1699.5
258     1700


If it can help, I have noticed that every time the distance "jumps", is at the end of the lap!

Thanks in advance!

[David Ferguson]

Please provide some information on the source of your various channels. What is the logging device? How is the distance channel generated? Are you receiving data from an ODB-II request, sampling a proximity sensor with a small number of pulses per revolution, or something else. What is the sample rate of the logged data channels?

Was the track map (and thus lap distance) made from data in this logged data file?

Are you using I2 Standard or I2 Pro? Do you have distance stretching enabled? (look here... I2->Tools->Corrected Speed and Distance...->Corrected Distance Tab)

[adrian]

It looks like there is a missed beacon correction occurring at the end of each lap and that you have a miss match between the lap distance set in your venue file and the actual measured lap distance.

As David has alluded to it is difficult to determine exactly what is going on with out a bit more information. In addition to the info he asked for are you able to provide the actual log file that shows this issue.

[madmatt]

ECU is a Motec M800, dash is a Motec C125.

I am using i2 standard. The distance stretching parameter makes no difference on the result.

For corrected distance, I've tried both methods (as shown on the pictures above). When using the lap distance method over the speed, the overall distance is correct, however the race time is still wrong.

Data is not received via OBD, but via sensors we directly connect to the ECU. We have a proximity sensor on 1 wheel.

Sampling rate varies, but most channels are logged at 20Hz.

The method used for the track map is using GPS data, and when looking at the track map it generates, it isn't good enough. Using lateral acceleration and speed is worse.

I have attached a log file to this message, and I have sent you via PM the password needed to open it.

Thanks!

[David Ferguson]

The problem is that you are not logging continuously. Your stop logging condition in the C125 triggers while you are still moving so it stops logging.

I suggest you change the stop logging condition to something like:

Engine RPM = 0 for 10 sec AND GroundSpeed = 0 for 10 sec.

That way both the engine and the vehicle have to be stopped in order to stop the logging of data.

Also -- you can calibrate your Ground Speed (wheel speed) to the GPS. I would suggest scaling your Ground Speed calibtation by 1.023