Closed loop feedback to glass linear encoders


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Thread: Closed loop feedback to glass linear encoders

  1. #1
    *Registered User* men8ifr's Avatar
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    Default Closed loop feedback to glass linear encoders

    All,

    1st I don't own any CNC parts yet but am planning to build a machine..

    One decision is software and BOB.

    Mach 4 it seems cannot support any closed loop feedback, it sounds like this is possible with a KFLOP board and dynamotion free software?

    Any other info? would anything else be needed?

    I was planning to use closed loop stepper drivers my plan was to have 2 closed loop paths - 1st the drivers to the rotary encoder and 2nd a glass scale to the kflop board.

    Has any-one done this? Is any other hardware required?

    Any other thought/input?

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  2. #2
    Gold Member TomKerekes's Avatar
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    Default Re: Closed loop feedback to glass linear encoders

    Hi men8ifr,

    Our KMotionCNC software and KFLOP can do closed loop to Step/Dir drives and typically works well because the motors can be moved in a controlled manner even when the glass scales are not providing information due to system compliance/backlash/stiction/etc. But overall performance will depend on your mechanics. See here for more info.

    KFLOP by itself can support this but only has single ended encoder inputs. See here for more info.



  3. #3
    *Registered User* men8ifr's Avatar
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    Default Re: Closed loop feedback to glass linear encoders

    Hi Tom, what is the speed limit in terms of reading from glass scales, if I had 1um scales which I assume would work? At 3000mm/min that's 50mm/sec and in 50mm there would be 50 X 1000 = 50,000 reads /sec but if your board sampled at 50kb /sec it would only 'see' the marks not gaps so I think it would need to sample at 3x 50kb/s 150kb/s per axis... This is obviously asking a lot, max possible resolution at max possible speed but I wanted to see if it is plausible? Feel free to comment on any experience of 1um scales.



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    *Registered User* men8ifr's Avatar
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    Default Re: Closed loop feedback to glass linear encoders

    And I guess I need to check 1um scales use quadrature the same as 5um scales... Maybe the resolution is due to more than 4x sampling which wouldn't work..



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    Gold Member TomKerekes's Avatar
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    Default Re: Closed loop feedback to glass linear encoders

    Hi men8ifr,

    1um resolution shouldn’t be a problem. KFLOP has hardware encoder Inputs that can count well over 1 million quadrature counts/sec. The max speed would be 1m/s or 60,000mm/min. KFLOP will sample the measured position every 90us and perform the Servo calculations.

    HTH



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Closed loop feedback to glass linear encoders

Closed loop feedback to glass linear encoders