Discussions

AC3.2.1 APM 2.5 Throttle pulsates in Loiter

Posted by Rolf Inge Sivertsen on February 24, 2015 at 1:47am

Hi.

I have a problem after updating AC to 3.2.1 from 3.1.5.

When in Loiter, the the speed of the motors rev up and down/pulsate quite rapidly. This was working fine when I was using previous versions of arducopter.

I have downloaded the logs, and have looked into accX, accY and accZ. These seems to be inside the range specified in the wiki at arducopter. (Log_vibrations.bin)

Please have a look at the Log.bin, and note the difference between ThrIn and ThrOut when I'm in Loiter mode.

Anyone having any idea what the problem may be?

Log.bin

Log_Vibration.bin

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Replies

- - - - Andy Piper > Cala April 15, 2015 at 6:49am
        
        Looking at the code it has changed A LOT between 3.2 and 3.2.1 - it's basically a bulk integration of the 3.3 sensor code as far as I can tell. I am not at all convinced that the default handling is right in the new code, but its changed so much that a direct comparison is very difficult. I'm hoping someone who understands (@Tridge? it was his change) can make an assertion one way or another.
  - Dave > Raph April 14, 2015 at 8:07pm
    
    I will have to reload 3.2.1 and try that setting. I wonder what the difference in 3.2.0 and 3.2.1 is.
    - Dave > Dave April 14, 2015 at 8:35pm
      
      Check out this blog on this.
      
      https://harkness3d.wordpress.com/2015/03/23/fixing-the-height-drift...
      
      Fixing the height drifting problem
      
      On the third day of trying to work out why the UAV had issues with holding it’s height, we found a solution. During research in to the problem my su…
Markus Horeld April 14, 2015 at 7:38am

Perhaps my question got lost among all the other postings. In short: By tuning down Throttle Rate and Throttle Accel I got rid of the pulsing, but Alt Hold behavior is still bad. What should I tune next to improve Alt Hold? Screenshots, log and quad specs here.
- Hubertus Paetow > Markus Horeld April 14, 2015 at 12:20pm
  
  As I wrote here before for my copter (Y6b with large props) it makes a big difference in alt hold performance wether I use a canopy or not - perhaps props influencing baro in pixhawk.
  
  Especially the dramatic drop after braking from fast forward flight is almost gone.
  
  Do you use some kind of canopy?
  - Cala > Hubertus Paetow April 14, 2015 at 3:00pm
    
    :o :o :o ; some weeks ago I bougth a salad and comes with a light weight canopy so I store it but not use yet, my Original build had a canopy with open slots for pressure but I removed because It's 100grs weight, for your comment but not conveinced I try with the salad canopy and the cuad flyes with a rock solid altitude hold :))), I test agressive flying side to side and perfect :O all the life of this cuad loose altitude when I fly agressively side to side, specially for left, I try many things and nothing or little changes including the first canopy; I complete surprise, today little wind, I'm going to try again in windy day. MANY THANK's for your comment Hubertus.
    
    Here my improvised canopy photo
    - Cala > Cala April 14, 2015 at 3:23pm
      
      Another surprise when I read logs, horrible vibs near limits, I never can fly with this vibs levels, my papers are burning :O (this copter is in rebuilding process waiting an ext compass and more adecuate props) ; I'm going to do more test to confirm if this is realy true on windy days and share here.
    - Marco Paggot > Cala April 14, 2015 at 3:05pm
      
      yeah, nobody read manuals this days...
- Cala > Markus Horeld April 14, 2015 at 8:04am
  
  Perhaps part of reply is here from instructions http://copter.ardupilot.com/wiki/altholdmode/
  - Markus Horeld > Cala April 14, 2015 at 8:32am
    
    There are no real tuning hints in the wiki. Randy's suggestions (No. 3 and 4) were the first explicit ones I found. And they worked fine regarding the pulsing motors. But I have no idea what to do to prevent the quad changing altitude that dramatically (see screenshots above).