Create Dataflash Log without full Drone Config with Pixhawk?

I’m trying to experimentally compare the effectiveness of various pixhawk vibration-absorbing mounts. I’m using vibration motors to simulate drone vibrations in a controlled way (on increments across a specific range of frequencies and amplitudes).
I have the Pixhawk connected via USB to my laptop with Mission Planner on it…the pixhawk also has an SD-card in it. Also important: for this setup I have no other connections to the Pixhawk (GPS, motors, etc.)
After running a trial, I open the SD-card on my laptop, expecting a .ULG log file of the most recent trial. But I don’t see any.

All I could find regarding this in the Pixhawk website is that:

  • “By default, [logs] are created after you first arm the vehicle.”
  • " Perform a regular flight (i.e. not just a gentle hover) of at least a few minutes and download the dataflash logs"

But how can I create a .ULG dataflash log without having to fully configure my pixhawk into a drone and flying it?
(I’ve attached a quick sketch of the setup I’m using, in case that helps)

Thank you!

Hi @ishaan_ganguly, you are doing a very interesting research.

I will try the next one but I don’t know if you can change it with Mission Planner or you will need QGroundControl.

Change this value to 2.

And change SDLOG_PROFILE to 19 (high rate enabled). This will give you a deeper vibrations log.

Give us your feedback! Good luck!

Thanks for the advice…I think I’ll try using QGroundControl once so I can do this.

But before I do so, I have a couple questions about it:

  • What file type should I expect to say the vibration data in (i.e. .BIN, .KMZ, .ULOG)? I ask because I plan on using for auto-analysis, which only accepts .ULOG files (worst case I guess I can try to convert file types or use a different medium for auto-analysis)
  • I know one concern with logging from boot to shutdown is that the extraneous dataflow could be problematic for memory. Will enabling high-rate be a problem from that stand-point? (boot to shutdown will probably be around 2-3 minutes for my trials)
  • Will the data-log be saved on the SD-card, or on my laptop? Since I’m connecting pixhawk directly to laptop via USB, the telemetry and RLOGs were being saved directly in a designated Mission Planner location on File Explorer in my laptop. If this is also the case with QGroundControl, memory could prove to be less of an issue.

Thanks again for you time!

Hi @ishaan_ganguly ,

Q1) Using PX4 the output will be .Ulog file, so you can us the PX4 flight review platform.

Q2) I always use the log start when arming, so I don’t have experience with the log start from boot. However, I don’t see any risk at the moment. Just try it.

Q3) The log will save within the SD card on the auto-pilot. You can access also to your saved logs on the SD directly from QGroundControl and dowload your PC by USB.
The quality of the SD card is very important (more if you are using “High rate”) if you don’t want to have any data dropout. I recoment you to use quality SD cards (no more than 32Gb) like SanDisk Extreme o others. I recommend not to use the default memory card that comes with the auto-pilot.

The memory of the card is not going to be a problem with 2-3 mins logs.

See you

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