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  1. #25
    Member TomKerekes's Avatar
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    Default Re: servo madness

    Hi jensenjim,

    Ok great it seems you are now responding to my posts, describing what you are doing, what you see, and asking intelligent questions..

    Moving the carrage in one direction moves the encoders in the same direction
    ok now we know both encoders are counting in the correct direction.

    On a side note in earlier posts you had the system operating somewhat properly. But now the parameters are set to basically crazy nonsense values (no PID and huge Feed Forwards). But that is ok for the moment. Before changing anything I would like to first understand and fix why there is basically opposite behavior between the two axes. Axis #1 moves the correct direction:

    servo madness-right-png


    But Axis #0 moves in the wrong direction:

    servo madness-wrong-png

    Can you see this?


    i can see the ential movement direction and ch 0 has none.
    I don't understand why you think Axis #0 has none. Rather it moves the wrong way and in fact much more - about - 800 counts rather than +100 counts like Axis #1.



    do I still need to work with the servo drivers or can this be corrected with the kmotion
    Most things can be corrected within KMotion. But your amplifiers seem to set very different because the same ~1V (200 count) pulse into each causes Axis #1 to move ~800% more. You might carefully re-check all the drive settings and pots to be sure they are set similarly as it appears you have something set completely different.


    The plots above are the results from a +200 DAC count (exactly the same) pulse to both both motor Drivers. There are many ways to reverse the response of a system such as mechanical linkages, electrically, or in software. I don't know the reason they are different on your system but we should be able to make them the same by changing the OutputGain of Axis #0 from +1 to -1. Please make that change and try the experiment again.

    I'm also guessing you have different IIR Filter settings for the two axes. You didn't show or tell us what they are so we don't know. I see some minor differences in the output (green plots) which should be exactly the same as your feedback terms (PID) are all Zero. Please post your IIR settings for both axes. Verify that you did indeed have them set differently, then clear all the filters for both.


    the two moves neet to be the same before coupling
    I don't really understand what you mean, but yes both axes must be functioning correctly before coupling them together mechanically.

    q1 what determines the blue line
    The blue line is the commanded trajectory. It represents what we are commanding the axis to do. In this case we are commanding the axis to move 300 counts at the specified Velocity, Acceleration, and Jerk

    q2 is the green line the actual voltage
    Basically yes. But it is in units of DAC counts where 2047 counts = 10V. So in your plots the green pulses of 200 DAC counts (use right side scale) are applying approximately 1V to the Drives.

    q3 the move command is a preset command that moves the servo fwd then back
    Well yes, but it is not preset. It will be of the size you specify and with the Velocity, Acceleration, and Jerk you specify.

    why is the blue line different from ch0 and ch1 , I disable the servo, reset the zero, and then enable the servo before I hit move
    They are actually exactly the same (+300 counts on left scale). But the plot auto scales in order to completely show the red and blue plots. Because in one case the axis moves the wrong way the plot zooms out so you can see it.


    the servo driver has pots for
    1 loop gain
    2 current limit
    3 ref in gain
    4 test/offset
    I'm not that familiar with your Drive. Eventually you will want the Ref in Gain to be set so when Kanalog puts out 10V it provides the maximum torque you will ever need. But for now I would at least make sure they are set similarly

    Regards
    TK http://dynomotion.com


  2. #26
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    Default Re: servo madness

    servo madness-ch0-2-jpg
    minus gain input


    prevous
    servo madness-ch0-1-jpg

    Attached Thumbnails Attached Thumbnails servo madness-ch0-1-jpg  
    Last edited by jensenjim; 02-25-2019 at 02:39 PM. Reason: wrong picture


  3. #27
    Member TomKerekes's Avatar
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    Default Re: servo madness

    Hi jensenjim,

    so minus gain on input flipped the motion direction
    Well true but no. You already verified the encoder (Input) direction was correct. So changing the Input Gain would cause it to appear to move in the correct direction when it is in fact still physically moving in the wrong direction. So instead the Output Gain should be changed as described in my previous post.

    Regards
    TK http://dynomotion.com


  4. #28
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    Default Re: servo madness

    lol magic voodoo electro tech guru language sure felt good for a second will continue



  5. #29
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    Default Re: servo madness

    servo madness-ch0-3-jpg

    isn't this 700 counts in the plus direction, I mean this looks like the correct



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    Default Re: servo madness

    servo madness-ch0-4-jpg

    when i change the output gain in kmotion it just increases the power of the servo but looks the same



  7. #31
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    Default Re: servo madness

    i am still trying to understand your prvous post, under
    (do I still need to work with the servo drivers or can this be corrected with the kmotion)



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    Default Re: servo madness

    servo madness-ch0-5-jpg

    ok blue line 500 comes from move input
    right side scale is max output 200
    red is the result of changing output from servo



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    Default Re: servo madness

    servo madness-ch0-6-jpg

    when i increase it to 2000 output it is over powered, the unit jumps hard
    i understand its almost max power 2047 being 10 volts



  10. #34
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    Default Re: servo madness

    servo madness-ch0-7-jpg

    i expected the blue line to match the red
    i raised the step to 1700



  11. #35
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    Default Re: servo madness

    servo 1 is moving in the wrong direction looking for a servo driver solution



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    Default Re: servo madness

    reversed the drive
    Attachment 413396


    thats 8 pictures, reminds me of a bad rotor balance day at work, 8 starts , boss gets steemedservo madness-ch0-8-jpg



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