Hello,

I have a 450 XQuad using an APM 2.6 Flight Controller and Neo6M uBLOX GPS. (Rotation is 180)

My stabilise and AltHold modes work beautifully. However whenever I put it on Loiter the Quad does its own thing. Starts Drifting Badly and even the controlls become sluggish. I need to quickly move back to stabilise to regain controll.

It is asif the quad is more locked in with AltHold then with loiter. Please help....

I have only tried Stabilise, AltHold and Loiter till now... Cannot get the loiter to work acceptable.

Can someone please help me by analysing these logs for me. Logs zipped and attached.

BTW - This is just day 2 with my APM 2.6 Quad. And I Just love it. Cant wait to perform an auto mission.

Thanks in Advance :-)
Arshish

logs.zip

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Replies

  • OK, First i would fix those loiter PIDs to match the image I posted from the manual.  Those values really should never have to change and you've got some things backwards in there.  I can't say that is the cause, but it could be.

    If you are absolutely sure you have the aircraft facing NORTH, and the compass is indicating WEST (272), then I think you have found the problem.  Your compass is rotated 90 degrees to the left.  With the compass pointing the wrong way, loiter and other modes that rely heavily on it will have a heart attack.

    • If the compass is on the bottom and GPS is on the top, that would necessitate the ROLL 180.  But that Yaw 270 is clearly not correct.  Set it for just ROLL 180.  This is also screwing up the GPS since it thinks the GPS is yawed 270 degrees.

      • You're welcome.  Glad it works now.  So are you back to ROLL 180 with the compass and GPS facing forward now?

        The Arducopter manual will illustrate all the defaults and tuning instructions for you. http://copter.ardupilot.com/wiki/tuning/

        I would also do an Auto Tune: http://copter.ardupilot.com/wiki/autotune/

        • OK, I think I'm following you now.  I thought you had it set for YAW270 all along.  I would favor rotating the module to face forward without needing the YAW270 setting.  But in reality, it probably doesn't matter.

          • Hi Pedals2Paddles,

            I basically did a complete rebuild of the quad after looking at the images on the "Managing Vibrations" page and since then my ALTHold has totally gone for a toss. I started this separate thread for the issue. Request if you could please have a look....

            http://diydrones.com/forum/topics/althold-stopped-working-please-he...

            Thanks,

            Arshish

            • Hi Arshish,

              I followed this discussion as I'm having similar issues on LOITER. My LOITER "works", but if I compare it with ALT_HOLD the copter response seems more sluggish (and not flyable in light/moderate wind). this happens both when the copter is in LOITER without any manual input from the pilot as when I add manual control to add correction to the position. Didn't have this issues with older versions of AC such as 3.0.1. 

              Now, I would like to have the copter to respond in LOITER an in ALT_HOLD the same way, and I was wondering if when in LOITER the copter still applies the same Rate_Roll and Rate Pitch Parameters of ALT_HOLD. Did you make any correction of PID parameters for LOITER?

               I attached some graphs; in the last you can see the difference in response RollInVSRoll in Alt_Hold and Loiter. This is what I would like to modify...

              Cheers

              Alberto

              LOITER_DVelYvsVelY.jpg

              LOITER_RelAlt_BarAlt_WPAlt.jpg

              RollInVSRoll_AltHold_Loiter.jpg

        • "You're welcome.  Glad it works now.  So are you back to ROLL 180 with the compass and GPS facing forward now?" - No. Ive left it as it is and am using the ROLL180-YAW270 offest in MP.

          Is this OK? or should I physically rotate the compass and remove the YAW offset?

          I will follow the tuning guide now.

      • OK. It Worked! Here is what i did. Originally, it was just ROLL180 when it was giving the error in direction.

        I left the compass as it is and changed it to ROLL180-YAW270 in MP and gave it a try. It worked. I cant say it was totally locked in cause the height kept dropping and was not able to hold perfect position BUT it was definitely working. Thank you SO SO SO much! :-)

        It all makes sense now! The GPS does not have any arrow on it. I called the seller and asked him which way was forward and oriented it as he explained. It obvious he had no clue what he was talking about!!!

        If my PID's were messed for loiter, could the Alt Hold PID's also be affected? Can you please share your settings for Alt Hold also.

    • After playing with the rotation setting and looking at the flight planner compas the ROLL180 YAW270 Seems to get things right. Should I physically turn the compas? or use the rotation settings?

      Chnaging values as in your screen.

  • OK, what about the PID values used by loiter mode?

    Loiter_Tuning.png?width=640

    Also, just for giggles here, you do have the mode set for LOITER, and not OF_LOITER, right?

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