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

- Andreas Lachan > Rob_Lefebvre April 1, 2015 at 1:47pm
  
  I agree it's too early to call it a bug but it is an issue at least some have.
  Problem for me with getting logs except the weather is that the pulsing is so bad it's hard not to crash (I'm still waiting for spare parts from my last flight) beeing sort of a noob pilot. I deleted my logs from my last crash by mistake while trying to figure out what was wrong and configuring everything again. If it's fine again with 3.1.5 I may give it a try when getting a bit more confident and prepared for it to go wrong.
  It would for sure be nice to hear some success stories as well :)
  Mine is an APM by the way.
Andy Piper April 1, 2015 at 1:01pm

I have noticed that my quad tends to lose altitude when moving forward fast in AltHolt and Loiter. I always put this down to some aerodynamic effect, but should this actually be happening? Loiter/AltHolt in hover seems ok. Never tried 3.1.5 - started on 3.2.
Andreas Lachan April 1, 2015 at 11:28am

From reading about the issue it seems to be related to 3.2.1 beeing a lot more sensitive to vibration. Not sure if that is a conclusion everyone woul agree with and I'm not sure if that is a bug either. Hopefully some developer is looking at it because the new flight modes are quite neat. It is not possible to be 100% vibration free.
- Ivan R > Andreas Lachan April 1, 2015 at 11:55am
  
  i definitely agree with that...cause I have 3.2.1 on another copter that doesnt have as much vibration and it works fine...so its that 3.2.1 is more sensitive to vibration than 3.1.5 for sure....
  - Marco Paggot > Ivan R April 1, 2015 at 11:59am
    
    Could you do IMU log and post what maximum vibration level do you have on copter?
    
    Methodics described here: http://copter.ardupilot.com/wiki/initial-setup/assembly-instruction...
Andreas Lachan March 26, 2015 at 4:33pm

For the record I have the same issue in both Alt hold and Loiter. Haven't tried with 3.1.5 yet.
- piku > Andreas Lachan March 27, 2015 at 1:48am
  
  It's help alot. Is someone reported it on buglist?
piku March 26, 2015 at 6:47am

Guys i have similar problem. Can you tell me it is the same issue ?

https://www.youtube.com/watch?v=60J3v9E889U
- Marco Paggot > piku March 26, 2015 at 6:52am
  
  Yep, it is. It drifts either up or down and have unsteady motor spin.
  
  Rollback to earlier version or try to isolate vibrations (official manual).
  - piku > Marco Paggot March 26, 2015 at 9:36am
    
    How can i downgrade to 3.1.5 ?