Discussions

Pixhawk Vibrations Log Wrong?

Posted by Tim on May 27, 2014 at 10:58am

I got my 3DR 2014 RTF Quad a couple months ago and have been flying/crashing it ever since.  :-)

My first logs, sans prop balancing, showed high vibrations (so much for "RTF"). In hindsight, that was probably expected since I didn't balance the props.

After I balanced the props (probably only did a fair job), my vibrations went from really bad to way too good. Too good in fact that I think that the accelerometers might be off or broken somehow.

I did some quick hovering today to get some fresh logs. See below for the vibrations graph and then a closeup where I was trying to keep it steady. I did 3 takeoffs and landings as can be seen so I know the accelerometers actually work. The vibrations look way too low. My quad can't be that good/balanced.

Is this normal? Is my Pixhawk somehow bad?

Thanks for any insight.

Tim

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Replies

  • Developer
    Craig Elder May 30, 2014 at 10:05am

    It looks correct to me.  What version of the firmware are you flying?  

    • Developer
      Craig Elder > Craig Elder May 30, 2014 at 12:08pm

      I recommend you update to the current copter 3.1.5 as there are a couple of bugfixes for Pixhawk.  3.1 still has an issue with downloading logs on Pixhawk that we did not include in those bug fix updates so you will need to continue to get the log files directly off the SD card.

      Your low vibrations are because 1) with the RTF, we have a tested solution with the foam and 2) on the Pixhawk we run the accelerometer sampling faster and the filtering better than APM. 

      Your graphs are similar to other RTFs I have seen.

    • Tim > Craig Elder May 30, 2014 at 11:56am

      Hi Craig, thanks for responding.

      According to MP 1.3.5 I'm running 3.1.2; which is what was loaded when I received the RTF.

      My concern is simply that it's too good knowing that I only semi-balanced the props, and when compared to 90% of the other postings on "good" vibrations. This is also compared to my first logs (which I didn't keep unfortunately) which showed very bad vibrations on the first flights before prop balancing.

      Either I'm a magical wiz at balancing props for my first time (no way), or something isn't right.

      If there are no other things to check, I'll live with it and see if I have any other symptoms.

      Thanks for any pointers.

      Tim

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