Autotune Issue - Causes Crash

I used auto tune late last night as there was no wind outside, went well. I didn't "test out" the new PIDS I just hit save and tried them out, well it was a disaster! The copter just did dips in each leg and kept getting more violent each time until it crashed.

I thought I messed something up so I went to terminal went erase and then reset .( i didn't reflash firmware though) and tried again, SAME issue as soon as it was a foot in the air it would go nuts and just kind of flip.

I then erase, reset and re flashed and it flew fine again (default PIDS) I did some FPV (the default PIDS seem to work great) and then on my last battery I decided to do an auto tune again. Went well was a little windier (7km/h winds) then I went saved the PIDS again and tested and once again it did its usualy crazy dance but not as violent this time  ( I also landed it pretty quick)

I attached a screen shot of the PIDS it saved.

http://snag.gy/nSYhC.jpg

Any thoughts?

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Replies

  • Ok, for a start the Imax is at 500 - for some reason mine shows 500 as well, I'm not sure this is a result of auto tune though.

    I have a friend with a similar problem. Auto tune went well but it now just rolls on take off. In his case the auto tune values were not saved, there seems to be a window of opportunity to corrupt the pids by writing a high Rate P should the Pix be turned off rather than disarmed. 

    • I compared my params and I noticed a value called Tune and it was triple,

      Also a value called Tune High and it was larger if I recall correctly as well. 

  • Motor/ESC sync problems.
    In short, it's your motors and ESC firmware that doesn't get along.
    Problems – Problems and solutions in India
    • I dis-agree. It fly's well on default pids. That would suggest ESC and motors are ok.

    • thank you for the insight, but I am not 100% certain that is it (but what do i know!) See the extra information.

      I am using the Q Brain 4in 1 ESC 25a with the Turnigy D2830 motors, I have run auto tune before and it did change my PIDS and it worked fine although it was pretty touchy BUT that was with a physically different ESC yet the exact same model (q brain 4-1 ESC) I also added since then a vibration dampening unit, (the little rubber balls type you can get from eBay)

      Could it be I got lucky before or does this extra information change your opinion?  The vibration dampening units a real pain to get out just to test PLUS it helps with alt hold.

      Thank you :)

      • of course, I could be wrong, and yes, it still sounds like sync problem.

        I've never seen APM/Pixhawk autotune cause a crash on any non-afftected controllers.

        Would suggest that you serarch for info on how to reproduce/check for motor sync problems,  do the stickbanging  - and test.  

        sync problems may be elusive, and naturally not 100% reproducible.  A little bit heavier propeller or different itch, lower/higher voltage etc can change the outcome between similar setup among 2 users as well.

        Basically - on a healthy multirotor - you will not see autotune causing crash.

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