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Logfile Analysis

The logfile viewer is a powerful tool to analyse AutoQuad’s behavior. Almost everything is logged like the IMU sensors, all GPS data, motor output, radio output, all temperatures and voltages.
To use to logviewer there has to be a log obviously. Simply insert a uSD card (confirm specs) in the AutoQuad and start flying. The log is written every 10 seconds so don’t worry about taking the uSD card out of the AutoQuad.

Using the logviewer

Start the Qgroundcontrol station, open the AutoQuad widget (default in the engineer tab) and click on ‘open logfile’

After opening, all recorded parameters are in the right bar.
You can now choose which parameters and values will be presented, you can choose different parameters together like in this example the GPS altitude and the estimated (filtered) altitude POSD to compare. They should more or less be the same. If not, the filter is not working as it should be.

Another example would be to view the GPS accuracy; the GPS_ACC. You should see a value that drops when the GPS fix will be better. In this example it drops from around 55cm to 31cm what is pretty good. The Ublox 6T that is on the release boards will do even better.

Example troubleshoot: Motor output clipped

In this example we display the output of the motors. It can be seen that around the maximum pwm (1900) clipping (capped lines) occurs. We can try to analyse why is that. You can delete some lines from the logviewer to see which of the motor(s) is capped. In this example 1 of the front motors.

That was indeed what was happening, a flip of the quad. The front motor cannot receive more output, that is limited in the AutoQuad.
We can increase that limit a bit, but looking at the cap it would not be enough.
But why ?. Maybe it needs 1 cell battery more (in this case from 3 to 4 cells), or a bigger prop. But during hoover (mid) the output is right around mid center (1500).
So higher voltage or bigger props would not help either. Then an other issue could cause it: not all ESC’s have the same output… And that was indeed the case, one of the ESC’s had another high range point and once all ESC’s where calibrated to the same range the flip would not happen anymore.

This page was created on 24-Jun-12 by menno. Last modified on 19-Aug-14 by kinderkram.