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Closed loop / servos

Discussion in 'Mods and Upgrades' started by daniel871, May 5, 2017.

  1. daniel871

    daniel871 Well-Known Member

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    What's that bit in the changelog about using steppers to sense limits?
     
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  2. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    @daniel871 not sure which commit you are referring to, but I do recall some talk about stepper hitting a physical limit drawing more power when stalled and that could be used to indicate that it hit an endstop. But I don't guarantee my memory is accurate.
     
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  3. jim3Dbot

    jim3Dbot Active Member

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    Personally, my gut says....the stalled motor current would work for an emergency stop situation......but, repeat-ability...not so much
     
  4. daniel871

    daniel871 Well-Known Member

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    Maybe it would be slightly more... accurate? If it was a closed loop system where the motors accurately reported their current position.

    That's far more expensive to set up though.
     
  5. jim3Dbot

    jim3Dbot Active Member

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    You are correct Dan, you would need a closed loop servo system with encoders or resolvers as feedback packages for super accurate angular positioning, but very cost prohibitive.........
     
  6. daniel871

    daniel871 Well-Known Member

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    Whatever happened to that Mechaduino project to turn stepper motors into closed loop systems?
     
  7. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    Well, I do understand why they might add that functionality to Marlin, after all it is the Swiss Army Knife of firmware for 3D printers. Agree that it would not be very accurate or even useful for our implementation.
     
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  8. jim3Dbot

    jim3Dbot Active Member

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    I quit following, it was hot subject last spring/summer............
     
  9. daniel871

    daniel871 Well-Known Member

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    Did some googling and it looks like they're still around. Version 2 of the motor is supposed to be available for ordering later this month (apparently they've fulfilled their kickstarter obligations).

    $65 for a 64oz-in Nema 17 motor with the custom PCB to make it closed-loop mounted and assembled up.

    http://tropical-labs.com/index.php/product/mechaduino-0-2-servo
     
    #9 daniel871, May 5, 2017
    Last edited: May 5, 2017
  10. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    Can we move this discussion to another thread since it doesn't really pertain to Marlin 1.1.0?
     
  11. jim3Dbot

    jim3Dbot Active Member

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    Thanks @daniel871 for the link....your the man.............
     
  12. jim3Dbot

    jim3Dbot Active Member

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    Sorry, was thinking that myself...........
     
  13. WheresWaldo

    WheresWaldo Volunteer ( ͠° ͟ʖ ͡°)
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    I asked @Geof to move all posts from #13 to a new thread.
     

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