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Thread: SBL Magnaturn Retrofit

  1. #49
    Gold Member TomKerekes's Avatar
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    Default Re: SBL Magnaturn Retrofit

    Hi Troy,

    That must be with the drive in Step/Dir Position mode?

    That looks reasonable to me. After the move the Output correction returns to near zero so not likely any loss of Step Pulses to the Drive.

    Peak position error 22 counts on initial startup (stiction?) Typical error ~10 counts. I don't know what resolution or speeds this relates to.

    Looks like position errors would be ~ 50 counts greater if running the Drive open loop without KFLOP making corrections because the Output is ~ 50 counts during the move.

    SBL Magnaturn Retrofit-troyzerror-png

    Regards



  2. #50
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    Default Re: SBL Magnaturn Retrofit

    Yes it is CL Step/Dir. What is the output shape at the end where it goes up and down?Seems very odd.
    But, if i continue to test moments like this i end up with growling of motor during movement and a plot that is like what you got in previous post. I get big position errors. To the point where axis returns about 1/2" short of start. And just continually gets worse.
    Also what causes the green output to be so rough looking? Is this just because of the mechanics of machine?

    Thanks
    Troy

    http://www.homecncstuff.elementfx.com/


  3. #51
    Gold Member TomKerekes's Avatar
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    Default Re: SBL Magnaturn Retrofit

    Hi Troy,

    The ramping up down at the end is where the motor is dithering +/- 1 encoder count is fairly normal. It is a bit abnormal that to correct 1 count of error KFLOP has to tell the drive to move 10 counts before it moves.

    Such noisy looking plots are normal. It is caused microscopic mechanical vibrations and such and mostly unavoidable.

    The other plot shows KFLOP needing to make corrections of a thousand or more steps to get the encoder to read the correct value. That means a large number of steps to the drive were lost or encoder counts from the drive were lost. I don't know why it would work sometimes and sometimes not. Did it "growl" when that previous plot was made?

    Regards



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    Default Re: SBL Magnaturn Retrofit

    No the growling isnt noticed until axis starts to really mis the return position. Before it gets extreme the axis will gradually return past the starting point by about .001" after each test movement. I have noticed that having the drive resolution set lower gets more constant results. But i dont have these issues with the other drive(xaxis) running the Z axis.

    http://www.homecncstuff.elementfx.com/


  5. #53
    Gold Member TomKerekes's Avatar
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    Default Re: SBL Magnaturn Retrofit

    Hi Troy,

    When you are swapping out the drives are you only swapping out the drive and are all cables unchanged?

    Before it gets extreme the axis will gradually return past the starting point by about .001" after each test movement.
    I don't really understand what that means.

    The "bad" plot you sent earlier is so big that the end of the motion back to the start is not shown. It would be nice to see what happens at the end in order to see if KFLOP's Output returns to near zero or not.

    You might also make open loop moves to see if the drive still has problems doing that.

    Regards



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    Default Re: SBL Magnaturn Retrofit

    Hi Tom,
    I have done both and get the same results.
    When a test move in Kmotion is executed, the axis returns back to where it started but overshoots by .001" each time the test is ran.

    Such noisy looking plots are normal. It is caused microscopic mechanical vibrations and such and mostly unavoidable.
    You reminded me that i wanted to change my ball screw mount design on Z axis. This should take out some of that noisy plot.
    Will be a couple days before i will be testing again.
    Thanks,
    Troy

    http://www.homecncstuff.elementfx.com/


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    Default Re: SBL Magnaturn Retrofit

    Hi Tom,
    Reworked my fixed ballscrew support for Z axis, which was also the cause of the .001" over shoot i was describing above. A nut came loose allowing the ball screw to move. But now iam getting much better results and can test again.Here is a plot after mount rework.
    Can you remind, what part of the plot graph should i look for the amount of error?
    And the axis never stops dithering after a test move by one count. Unless i disable ,zero, and enable. Sometimes have to do this procedure a few times before it will stop.
    This plot is using the Z axis Drive on the Z axis. This drive is the one that has been acting differently than the other on X axis. Right now iam letting it sit idle and will test move again. Usually movement and response would start getting worse after axis is powered on and sitting for an hour or 2.
    Now iam back to where i left off. And back to electrical noise trouble shooting. As per DMM i have installed filters on the Main Power to drives and on the output of my 24VDC supply. If all goes well and the issue has been fixed i will be trying analog again.

    Thanks again,
    Troy

    Attached Thumbnails Attached Thumbnails SBL Magnaturn Retrofit-zaxisdriveclstep1000-jpg  
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    http://www.homecncstuff.elementfx.com/


  8. #56
    Gold Member TomKerekes's Avatar
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    Default Re: SBL Magnaturn Retrofit

    Hi Troy,

    The error in that plot would be the difference between the red and blue plots. But on that scale you can't really see the difference. So change the Plot Type to Position Error, Output vs Time.

    Why do you think you have a noise problem?



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    Default Re: SBL Magnaturn Retrofit

    Hi Tom,
    That much i understand/remember, what i was talking about is when looking at the Plot Position Error, is the amount of error measured the difference in the height of plots when zoomed in or is it at the 0 scale on the left of screen ?
    The noise assumption came from DMM when i told them what was happening with the one drive missing steps at high resolution and growling.

    Troy

    http://www.homecncstuff.elementfx.com/


  10. #58
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    Default Re: SBL Magnaturn Retrofit

    Hi Troy,

    hat much i understand/remember, what i was talking about is when looking at the Plot Position Error, is the amount of error measured the difference in the height of plots when zoomed in or is it at the 0 scale on the left of screen ?
    The error (blue plot) uses the left scale. The output correction (green) uses the right scale.

    So in your plot you can see when the move begins the axis initially lags behind with an error of ~90counts. Then KFLOP makes a correction of ~100 steps and reduces the error toward zero.

    SBL Magnaturn Retrofit-poserr-png

    The noise assumption came from DMM when i told them what was happening with the one drive missing steps at high resolution and growling.
    Oh



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    Default Re: SBL Magnaturn Retrofit

    Ok. Update: After placing the filters on the Drives Main power input, problems appear to have been fixed. And also have the drives running in analog mode and tuned very well in Kmotion.
    Now iam working on the Z index pulse from drive output. I currently have the Z index connected to Kanalog JP2 Differential Inputs. When doing a test move by Step/Reponse window in Kmotion, shouldn't there be counts showing for the Z axis index on the Axis window? Currently iam not showing any counts for Z index on either X or Z axis.

    Troy

    http://www.homecncstuff.elementfx.com/


  12. #60
    Gold Member TomKerekes's Avatar
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    Default Re: SBL Magnaturn Retrofit

    Hi Troy,

    Now iam working on the Z index pulse from drive output. I currently have the Z index connected to Kanalog JP2 Differential Inputs. When doing a test move by Step/Reponse window in Kmotion, shouldn't there be counts showing for the Z axis index on the Axis window? Currently iam not showing any counts for Z index on either X or Z axis.
    I'm not sure I understand. But no, an Index pulse is usually a single signal pulse. It isn't A B quadrature and won't cause counts. It is usually a tiny pulse that will be hard to see by eye. Normally a C Program is used to detect it during the Homing process. See the SimpleHomeIndexFunction.c and SimpleHomeIndexFunctionTest.c examples.

    HTH



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