Discussions

Yaw control with compass enabled

Posted by Al Ros on May 9, 2011 at 5:49pm

Hi Folks

 

I am really having a problem with my yaw stability and I am hoping someone can point me in the right direction.

1st if compass is diabled in either Arducopter 2.x or ardupirates code. I have excellent yaw control just like on my mikrokopter.

If I enable compass at default PID settings, yaw hold is very sloppy (better at default values for arducopter 2.x) . for example in ardupirates code I have to increase P and D to 7.5 and 3.5 otherwise it keeps rotating past when I let go of the stick. But at these high PID values yaw is not smooth and hunts (not really oscillates) and the hunting affects roll and pitch stability

 

My Yaw gyro must be ok since without compass yaw is great. My compass heading seems ok and is relatively steady. but my issue is now with two different codes.

 

Is this a bad compass, or is this what other folks are seeing as well? if anyone was able to correct sloppy yaw - how did you do it.

 

Roll and pitch sabilization are perfect by the way

Thanks

Al

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Replies

  • Chris Barlow May 19, 2011 at 12:49pm

    Ok, so what do you advise?  Should i video the issue and attach the log.  Happy to do whatever is needed to get this issue recognised, though as the most talked about issue on the forum i am suprised no one took notice yet!

     

    Personally I am using all standard kit...APM and latest oilpan, plus diy drones mag and bundled gps....

  • Brent May 18, 2011 at 12:51pm

    I don't have a compass installed and have funny yaw issues as well so it's possible the bug is in the mixing.

    When I yaw left in a hover it turns smooth but will try to "unwind" after yaw input is relaxed. Yaw right and it takes of trying to spin fast for no reason ??

     

    I will try to post up a video if it stops raining for afew minutes.

     

    Setup: Quad X configuration running the lates code from the last mission planner.

  • Vincent Mees May 18, 2011 at 9:23am

    I just loaded the recent code with the MP.

    I noticed that the motor levelscan't been seen anymore with the new MP.

    After a lot of adjusting of the PIDs I finally got it flying but still some oscillation.

    A thing I still have since the start of the beta is if I for example fly sideways to the right and stop, the quad suddenly starts to yaw a certain degrees (about 90- 130°) to the right.

     

    Which PID should I change when I want to decrease the hardness when manualy yawing with the TX. Now it is very strong reaction.

     

  • Saiful Azuwan May 17, 2011 at 2:58am

    I think I found the problem for hexap.See motor_hexa_.pde

    //Back side
        motor_out[CH_2]        = g.rc_3.radio_out - g.rc_2.pwm_out;        // CCW    BACK
        motor_out[CH_3]        = g.rc_3.radio_out + roll_out - pitch_out;    // CW,     BACK LEFT
        motor_out[CH_8]        = g.rc_3.radio_out - roll_out - pitch_out;    // CW    BACK RIGHT

        //Front side
        motor_out[CH_1]        = g.rc_3.radio_out + g.rc_2.pwm_out;        // CW     FRONT
        motor_out[CH_7]     = g.rc_3.radio_out + roll_out + pitch_out;    // CCW     FRONT LEFT
        motor_out[CH_4]     = g.rc_3.radio_out - roll_out + pitch_out;    // CCW     FRONT RIGHT
    /*****************************CHANGE THIS LINE******************************
        // Yaw
        motor_out[CH_1]        += g.rc_4.pwm_out;    // CCW
        motor_out[CH_3]        += g.rc_4.pwm_out;    // CCW
        motor_out[CH_8]     += g.rc_4.pwm_out;    // CCW

        motor_out[CH_2]        -= g.rc_4.pwm_out;    // CW
        motor_out[CH_4]        -= g.rc_4.pwm_out;    // CW
        motor_out[CH_7]        -= g.rc_4.pwm_out;      // CW

    *******************************LIKE THIS*****************************************/

     

    // Yaw
        motor_out[CH_2]        += g.rc_4.pwm_out;    // CCW
        motor_out[CH_7]        += g.rc_4.pwm_out;    // CCW
        motor_out[CH_4]     += g.rc_4.pwm_out;    // CCW

        motor_out[CH_1]        -= g.rc_4.pwm_out;    // CW
        motor_out[CH_3]        -= g.rc_4.pwm_out;    // CW
        motor_out[CH_8]        -= g.rc_4.pwm_out;      // CW

     

    Walla... my yaw works so stable now. Hope devteam can verify this.

     

  • Joshua Ott May 17, 2011 at 12:30am

    I'm using AC2x

    DIY Drones Compass V2.0, components down pins forward using iI2C cable

    Declination set in "Setup" to 10.38 per NOAA.

    Having similar yaw issues when compass is enabled, bird spins right, I give full left rudder to counteract, and after a few moments I loose all rudder input and can not even disarm motors with full left rudder no throttle. If I go to Raw Sensor in AC2 setup the Yaw dial shows apprx. 20degrees as a neutral point with no stick input, sensor does show movement when I spin it, but returns to 20degrees when still.

    Disabled compass and everything behaves. As a side note I have never been able to see any compass readings with the two mags that I have, I've checked them in APM planner and Arduino terminal, always straight zeros across the board. I bought them back in Dec. of last year. They had the 204 resistors, I removed them and bridged the pads, but no difference.

    Thank you

  • Developer
    Jason Short May 16, 2011 at 10:16pm
    I'll whip up a really simple yaw hold demo to see if we can narrow down on the problems.
  • emile May 16, 2011 at 2:51pm
    I have same issue. Flying with compass enabled gives really strange behaviours.
    It always start yawing left or right. But that could be the motors spinning up and generating magnetic fields.
    But sometimes when flying, I try to yaw and it gets back to the original position.
    This happens when very short yawing is done (20/40 degrees).
    I also had the quad starting to spin around without touching any control.
    I left it yaw and then stopped with a touch to the stick.
    Other times it just tries to rotate 20 deg. while going straight.

    @Jason how much should the values change when the copter is tilted? Mine go pretty far away...

    Emile
  • Sebastian Gralla May 16, 2011 at 2:13pm

    did you check your power cables? (magnetic fields and stuff...)

    did you check magneto reading in flight?

  • Chris Barlow May 16, 2011 at 2:04pm

    It's not hardware, the NG 527 works fine....it's got to be something to do with the software though I am suprised there are only a few of us complaining about this...can any of the team comment on this, is it something you are aware of,/looking at fixing?

    Without proper heading working I am sure GPS hold wont work...daren't try it yet....

  • LAIC May 16, 2011 at 4:04am
    same problem: if i enable the compass my A.C starts turning in the air. my MAG board has components up and the pins heading forwards. The Compass test shows correct vals.

    ??
This reply was deleted.

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