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

- LTMNO > LTMNO April 17, 2015 at 11:04am
  
  Well, after doing about 10 flights today... tuning the APM manually, I can get a very stable Stabilize flight... very responsive... actually, the Loiter isn't that all bad either... just a little flutter up and down. The AltHold on the other hand is not behaving. I then proceeded to try a version even further down the chain. Hexa_ArduCopter_3.1.2.Hex and that had the same result. I don't think the problem is software/firmware. I believe we/I have a hardware problem. I don't know what it could be as my logs do indicate some Power Issues from more than 0.3v difference when in fact I get 0.429v delta.
  
  I am going to start with my Power Module and then test again.
  
  Here is the latest Logs... In case anyone is interested...
  - LTMNO > LTMNO April 17, 2015 at 2:47pm
    
    So, here are the results of a new PM put in place....
    - Marco Paggot > LTMNO April 18, 2015 at 8:42am
      
      It seems to me, your power module just not have enough power.
      - 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