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 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.
  - Cala > Marco Paggot April 15, 2015 at 2:43pm
    
    Woman ;)
    - Marco Paggot > Cala April 15, 2015 at 3:25pm
      
      Woman? That flies copter? Mary me! :D :D :D
      - Cala > Marco Paggot April 15, 2015 at 3:50pm
        
        build and flies copter and plane..........or try ;)
Dave April 14, 2015 at 7:49pm

I had version 3.2.0 on my450 quad. It has flown great with 3.1.5 and 3.2.0. Ijust installed 3.2.1 on it and it was wandering all over and it was going up and down in loiter and alt hold. I rolled it back to 3.2.0 and it flies great again. There is something in 3.2.1 that doesnt work well with a apm 2.6.
- Raph > Dave April 14, 2015 at 8:05pm
  
  I'll have to second this!
  
  I managed to fix my issues by changing the INS_MPU6K_FILTER param. Previously I had great flying with it set to 42 (before 3.2.1 upgrade); now, i changed it to 10 and i'm back to flying perfectly. Attached is a log with a great flight - the vibrations are showing much lower but I did not change anything physically; just the parameter i mentioned.
  
  I really hope some devs can give any insight into what's going on.. really makes upgrading firmware a nightmare - this has been a 2 week project for me :|
  
  2015-04-14 22-26-33.log
  - Andy Piper > Raph April 15, 2015 at 2:15am
    
    So this is really strange. If you look at the setting:
    
        // @Param: MPU6K_FILTER
        // @DisplayName: MPU6000 filter frequency
        // @Description: Filter frequency to ask the MPU6000 to apply to samples. This can be set to a lower value to try to cope with very high vibration levels in aircraft. The default value on ArduPlane, APMrover2 and ArduCopter is 20Hz. This option takes effect on the next reboot or gyro initialisation
        // @Units: Hz
        // @Values: 0:Default,5:5Hz,10:10Hz,20:20Hz,42:42Hz,98:98Hz
        // @User: Advanced
        AP_GROUPINFO("MPU6K_FILTER", 4, AP_InertialSensor, _mpu6000_filter, 0),
    
    0 is supposed to mean default which I think is now 20Hz (was 42Hz). So if setting this to 20 gives different behaviour to 0 it has to be some kind of bug in the initialization of the sensor. Given that there was quite of lot of work in 3.2.1 specificly around sensor failure detection, it seems quite likely that something was introduced in 3.2.1 to cause this.
    - Cala > Andy Piper April 15, 2015 at 6:45am
      
      In my copter was 0 by default and I changed to 20 and I feel It was better, then I read that 0 and -20 was the same and think that other thing changes my cuad .