Does wind badly affect the APM?

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

Do you have the barometer covered with some foam? Sounds like that could be causing your issues. While APM does handle wind pretty well, the rapid change of pressure can cause issues.

The toilet bowl symptom is typically magnetometer issues which would be separate from the altitude issue. Given that under optimal conditions this didn't happen I would say this is likely the result of vibration, you may want to either try and external mag or try to eliminate vibration.

I would follow the recommendations of others and attempt alt. hold. Get that working well then move to some other modes.

Basically to sum it up, when you are in wind you are amplifying any issues dealing with vibrations and wind gusts tend to bring rapid pressure changes which can greatly effect the height especially at low altitudes.

Replies

- Quentin Mayberry > mP1 March 25, 2014 at 1:04am
  
  I wonder why it would do that, when it worked perfectly with very little wind, same route too.
  - Chuck > Quentin Mayberry March 25, 2014 at 6:50am
    
    Do you have the barometer covered with some foam? Sounds like that could be causing your issues. While APM does handle wind pretty well, the rapid change of pressure can cause issues.
    
    The toilet bowl symptom is typically magnetometer issues which would be separate from the altitude issue. Given that under optimal conditions this didn't happen I would say this is likely the result of vibration, you may want to either try and external mag or try to eliminate vibration.
    
    I would follow the recommendations of others and attempt alt. hold. Get that working well then move to some other modes.
    
    Basically to sum it up, when you are in wind you are amplifying any issues dealing with vibrations and wind gusts tend to bring rapid pressure changes which can greatly effect the height especially at low altitudes.
    - Quentin Mayberry > Chuck March 25, 2014 at 10:10am
      
      No idea about the foam Chuck, its a new 2.6 APM with external gps/mag module, I haven't added anything. Our previous one was a version 2 APM with everything on the board, worked a treat for years in any wind conditions.
      
      I have been checking the 3DR X8 parameter settings with my settings and have modified ours to match theirs, so it will be interesting to see what difference that makes as there are a few subtle changes.
      
      More tweaking to come no doubt.
      
      Thanks for the suggestions.
  - mP1 > Quentin Mayberry March 25, 2014 at 3:15am
    
    I guess then my suggestion is wrong. Are you sure you didnt change something else that might affect the interference that affects the compass ?
    
    Have you verified the compass is working properly now after the last dodgy run ?
    - Quentin Mayberry > mP1 March 25, 2014 at 5:36am
      
      No changes at all other than charged the batteries! Yes the compass has been checked and it seems fine. I am just waiting for the weather to improve and will go and try again!
T3

Richard Boyhan March 24, 2014 at 12:59pm

Sounds like your THR-MID might be set to low. Have you tried altitude hold. If altitude hold works then loiter alitude will work.
- Quentin Mayberry > Richard Boyhan March 25, 2014 at 12:28am
  
  Haven't tried alt hold yet, but if the thr-mid position was set too low, why would the drone climb and require the throttle to be lowered to stop it?
  - T3
    
    Richard Boyhan > Quentin Mayberry March 25, 2014 at 5:27pm
    
    Altitude hold is used by loiter. If altitude hold does not work nor will loiter work. THR-MID is where the throttle is set for altitude hold. Normally it is set at 500 or 50%. If your throttle is set at less than 50% to maintain altitude hold, then your copter will climb when switched into altitude hold or loiter. Lower the throttle down and the copter holds altitude. But when you switch out of altitude hold or loiter the copter drops.
    Vibration problems will cause the copter to bounce up and down and not hold altitude.
    Toilet bowl affect happens when you have interference with your compass. Interference problems come from power systems or metal screws or other metal near the compass.
Quentin Mayberry March 24, 2014 at 10:50am

This is the latest log file, don't know why it didn't attach to the original message.

2014-03-24 11-16.log

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Does wind badly affect the APM?

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