Servo Jitter in Fly Mode

Posted by Christoph on September 23, 2011 at 1:24pm

Is it normal that the servos jitter if the ACM is in fly mode?

The jitter can not come from electrical noise, because there is no jitter at all as long as I am in CLI mode and e.g. setting up the board with the "heli" commmand.

In my opinion it is triggered by the noise of the gyros and accelleration sensors, so the ACM wants to correct by swashplate movements, which leads to the servo jitter.

 

Do you have the same effect or are all your servos "quiet" as long as the board is not moved?

 

Would it help to solder the filter on the oil pan?

 

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Replies

  • Developer
    Randy September 25, 2011 at 1:21am

    I've just checked in the servo averaging to trunk.  You can see the code here.

     

    To change the servos to analog (125hz) go into CLI mode, select 'heli' and type "ua".  which means Update rate, Analog.  Predictably you can set it back to digital (250hz) by typing "ud".

     

    You can adjust it more finely by using the AP_MissionPlanner instead. Go to the configuration screen, connect, the press "refresh parameters", then look for "SV_AVG" and set it to one of the following:

    0 or 1 = no averaging (250hz) - default for digital servos

    2 = two samples (125hz) - default for analog servos

    3 = three samples (83.3hz)

    4 = four samples (62.5hz)

    5 = 5 samples (50hz).

     

    I tested with the common HKT900 servos..the blue ones from hobbyking and found they were happy with 125hz so that why I set the default for analog servos to that.  

     

    Remember to reset/erase your eeprom with the latest version.

     

    Jason's also put some other changes in there that likely improve something!  latest version is 2.0.45

     

    Please tell me if you have any problems!

  • Dusan September 23, 2011 at 2:59pm
    Do you have telemetry module connected? Is it to close to APM?
    I hade have similar problem, and by pushing telemetry module future apart from APM and changing its antenna polarization problem disappeared. It seems that RF from xbee is affecting multiplexer.
  • malcolm churn September 23, 2011 at 2:25pm

    No i dont, i'm not a coder, one of the other guys on here should be able to tell you. 

    Sorry i can't be any more help.

  • malcolm churn September 23, 2011 at 1:27pm

    What mode are you in .... stabilise... alt_hold etc?

This reply was deleted.