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Does wind badly affect the APM?

Posted by Quentin Mayberry on March 24, 2014 at 10:48am

I have upgraded our quad to an octaquad and we have been conducting test flights using AC3.1.

The first test flight 18th, was in relatively calm wind conditions and the IMU showed quite low X,Y & Z settings. The drone flew very well except it didn't hold the loiter height, it tended to climb so that had to be manually adjusted with the throttle until it was stable. The RTL worked well and kept its height when returning.

The second test flight was today 24th in 35 KPH gusting wind conditions. Nothing had changed with the octaquad, except the wind. The IMU data showed increased vibration and the drone didn't behave too well. It wandered off down wind (as you would expect) until put into loiter, when it maintained its position, but started climbing again, so needed manually stopping by lowering the throttle. The RTL didn't work too well as half way back it started to enter a large circle and ended up going away from the home location. I tried putting it into loiter which caused a violent reaction in roll and pitch. It did settle but started climbing again, so I had to take control and bring it back manually.

So now that we have moved to accelerometers, do they become adversely affected by the wind? Version 2.8.1 didn't mind about strong or gusting winds and we were able to fly it in stronger winds than today!

2014-03-18 11-27.log

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Replies

  • Cala April 15, 2014 at 6:01pm

    Did you check compassmot?

    • Quentin Mayberry > Cala April 17, 2014 at 2:09am

      No, it is currently set to disabled.

      I don't understand why the octaquad flies OK in Stabilized, ALT Hold and RTL, but goes nuts in loiter.

      Is this the compass interference from the motors causing this then?

  • Quentin Mayberry April 15, 2014 at 9:23am

    Been out testing and tuning again today. Wind was fairly strong again and a bit gusty (15 to 19 MPH gusting up to 31 MPH typical for Scotland)

    I am assuming the vibration is OK as it is well within the stated parameters on the instruction guide.

    3701709831?profile=original

    Spent quite a bit of time trying to calm the octaquad down and eventually ended up with the following...

    3701709780?profile=original

    Unfortunately the octaquad is still very lively in Loiter mode, I tried going up and down on the PID settings for loiter but gave up and reset to 1. This is what it looks like in loiter (not a brilliant clip unfortunately)...

    As you can see it still wanders around and pitches and rolls way too much in loiter. I don't know where to go with the tuning next, can anyone suggest what to try please?

  • Quentin Mayberry April 10, 2014 at 2:22pm

    Well had a chance to check over the octaquad and found two props out of balance.

    Test flew it yesterday (log for the 9th) in quite a strong steady wind. It performed very well, pretty stable loiter on the spot.

    Alt hold sorted, the THR Mid was too high.

    Made a few adjustments today (log for the 10th) to stabilize roll and rate roll. Different location and quite gusty not as steady a wind as yesterday. Very stable in stabilized mode but quite active in loiter and started to go around in a fairly large circle. RTL was pretty good.

    So what would be the best parameter to adjust now, loiter PID maybe?

    2014-04-09 14-01.log

    2014-04-10 21-14 -1.log

  • T3
    Ted Van Slyck March 25, 2014 at 5:44pm
    What props are you running? If suddenly vibes went up and the only change is gusty wind that could be the issue. My APC 12x3.8 props make a buzz noise when the quad rapidly corrects in wind. I have some stiff 11" carbon fiber props that run silent even through rapid corrections. Naturally the noise will correspond to vibration.

    This sounds like vibration. Climbing in loiter / alt hold is classic vibration. Solve that, solve the problem.
    • Quentin Mayberry > Ted Van Slyck March 26, 2014 at 4:30am

      Hi Ted,

      Graupner EProps 10 x 5

      no-image-available.gif

      I noticed the THR-MID was set at 500, yet the S3DR X8 is set at 450. I have lowered mine along with some other changes and will hopefully test fly it again today as there is not much wind. 

      Thanks for the comments guys, I will look at checking each individual prop motor combination to see how well balanced they are. 

  • MR60
    Hugues March 25, 2014 at 11:24am

    Hi,

    Looking at your logs I see that your vibrations (Z acc) is quite high between -6 and +14, when it should be smaller than -8 and+12. For best behaviour, in a hover you should be able to get -1 and +1, using Kyosho zeal tape under your FC.

    3701692118?profile=original

    Not sure if this is your only issue, byt high vibrations certainly does not help for a stable loiter, nor alt hold.

    https://storage.ning.com/topology/rest/1.0/file/get/3701692118?profile=original
    • Quentin Mayberry > Hugues March 25, 2014 at 11:59am

      Hi Hugues, I assume you were looking at the log for the 24th? The 24th shows the larger vibes, the only difference is the wind strength and gusting. The 18th shows the usual vibes with not much wind between -9 and +10. Add the stronger wind and they are as you say (I do have the zeal tape under the APM).

      -1 and +1 on an octaquad camera ship, that would be very impressive!

  • mP1 March 25, 2014 at 12:31am

    The large circle thing sounds like toilet bowling where you compass is giving the wrong direction.

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