MR60

Unexplained loiter drift V3.1.2

Posted by Hugues on March 24, 2015 at 10:30am

Hi,

I 've got an issue on an octo build  : an explained drift  in loiter mode (seems to the right each time but could have been the Wind at that moment). Stabilize is fine.

I've looked in the log and I see a discrepancy between X, Y velocities and Desired corresponding velocities, which is indeed a sign of a bad loiter. But Why ? Accelerations are perfectly fine (AccZ) is contained to +/- 0,1g, compass calibration has been redone and is fine, using an external 3DR GPS+MAG. The frame looks fine too (nothing twisted, everything solid).

What could be the cause ? I need help of an expert on this. Log (and Tlog for vibes) attached.

2015-03-22%2015-37-55.tlog

2015-03-22%2015-40-01.bin

Please note that the firmware is still an old one : V3.1.2 (NOT to confuse with the most recent one V3.2.1)

You need to be a member of diydrones to add comments!

Join diydrones

Email me when people reply –
Follow

Replies

  • Cala March 25, 2015 at 6:11am

    3701966806?profile=original...or dig deeper ;)

    • MR60
      Hugues > Cala March 25, 2015 at 1:10pm

      OK lol.  I hope this is only a GPS issue. In any case I am going to upgrade this craft to the last firmware and will test again. 

  • MR60
    Hugues March 25, 2015 at 4:02am

    3701966481?profile=originalI found this in my log, velocities and desired velocities are not at all following each other. What's the cause of that ?

    • Cala > Hugues March 25, 2015 at 6:03am

      GPS  GPS  GPS  GPS GPS ALIEN

      The tree flights with bad GPS?, velocity is calculated with gps so I suppose that if GPS is not working well, It couldn't calculates well the velocity, If I don't have 9-10 sats and HDOP under 2 (1.5-1.7) my copter drift, but it's strange your up and down gps signal, it's look as an interference perhaps?

  • Cala March 24, 2015 at 3:33pm

    your HDOP looks worse, where is your GPS? any camera or FPV near?

    3701966277?profile=original

    • MR60
      Hugues > Cala March 24, 2015 at 11:42pm

      I checked compass and recalibrated it too. If the cause is poor GPS reception,  then I still do not understand why on three separate flights in the same afternoon it drifts exactly in the same direction ?

      PS: there is no alien base underground:)

    • Cala > Cala March 24, 2015 at 3:46pm

      Did you check your compass? but for me is GPS problem ;) , try again with 10 sats and HDOP under 2 ;)

  • Cala March 24, 2015 at 2:54pm

    Hugues, your GPS looks horrible

    3701966358?profile=original

    • MR60
      Hugues > Cala March 24, 2015 at 3:03pm

      Hi Cala, HDOP was about 2-2.1 which is at the limit for good loiter. The graph shows between 7 and 8 sats.

      This however does not explain the loiter drift where the craft rolls to the right in a straight line (keeping altitude) as if it wanted to reach a waypoint far away in a straight line to the right...

    • Cala > Hugues March 24, 2015 at 3:28pm

      here, with 7 sats I can't fly in loiter....

      ...or perhaps the allien moves to there LOL

This reply was deleted.