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

- - - - WCP > Marco Paggot April 18, 2015 at 1:40pm
        
        Still having the AltHld problem Changed several Parms Is the real problem vibrations ?
        
        Pleas have a look.................
        
        2015-04-18 13-33-12.log
        
        Cala > WCP April 18, 2015 at 2:19pm
        
        High vibrations, you have to resolve that, here many great info to do it http://diydrones.com/forum/topics/vibration-isolation-and-dampening...
        
        LTMNO > WCP April 18, 2015 at 2:17pm
        
        Well, from a quick glance your X/Y are well over the -/+ limits of -3/+3
        
        Your Z is well over the -5/-15.
        
        I would definitely fix the Vibrations...
        
        Was your crash significant? Any damage?
  - LTMNO > LTMNO April 17, 2015 at 11:48am
    
    oops.. the log file..
    
    2015-04-17 13-50-10.log
- LTMNO > LTMNO April 17, 2015 at 6:47am
  
  Question for those who know...
  
  Does a fluctuation of 4.7v to 4.4v an issues in Power to the APM?
  
  https://dl.dropboxusercontent.com/u/58223709/_WEB/Flight_6_Outside.log
  - Marco Paggot > LTMNO April 17, 2015 at 11:15am
    
    With power issues like this I doubt you get steady flight, sensors need very stable power source to give accurate measured values. In your case 45 degree angle can give (for example) 1.5V and 1.4V depending on input voltage, system gets it as 45 degree -> 40 degree not knowing that it's just input voltage fluctuations.
    
    Get stable power source.
    
    I don't use APM power module power source at all. After a couple of brownouts I returned to my well tested 7-38V 7A BEC which works flawlessly powering ALL electronics without any limitations.
    
    I really don't understand why 3DR could not design 10A power module, which will be more than sufficient for any copter/plane/rover needs.
    - LTMNO > Marco Paggot April 17, 2015 at 12:01pm
      
      Hi Marko, thanks for replying... I don't like to problems in the logs so I am going to switch that Power Module out. Its not 3DR but in an HK one.
      
      Power Module HK
      
      But I have never had problem with my 3DR Modules... have run those on all my quads... that being said, I give up at this point with tuning and firmwares and am going to try out the hardware change.
      
      Thanks again for replying...
      
      Cheers
- LTMNO > LTMNO April 16, 2015 at 6:03pm
  
  The Vibrations with GF Props are 2/-2 for XY and -5/-15 for the Z
  
  Is there any concern for Vcc Test = Test: VCC = WARN - VCC min/max diff 0.338v, should be <0.3v
  
  ArduCopter V3.1.5 (3c57e771)
  
  (is this the correct version?)
Cala April 15, 2015 at 9:30am

For peoplle thats until not solve pulsate problem, i posted in aonther post but a compromise solution that I found until resolve the main problem was to fix something 50grs up the APM with doble sided tape,

What I did: my copter was pulsating in Pos-Alt hold I put coins until stop pulsating (be carefull with compass) that's give me 50 grs aprox and them I change coin with some pieces of wood that I don't removed yet waiting for an ext compass, Pherhaps it's usefull for anyone else as a temporary solution and easy to try.

here how is now, as soon as I have the compass I'm going to try to remove the wood and see what happens with pulsates fixing the APM to the main plate.

.
- Marco Paggot > Cala April 15, 2015 at 11:38am
  
  Yeah, man. Copter is the kind of device that SHOULD carry extra useless weight :) :) :)
  
  Frankly say, changing INS_MPU6K_FILTER to 20Hz made things much smoother. I'll make a couple of experiments on bigger Quad and then write here if it solves problem completely.