Actuator signals help!

Discussion in 'The Projects Forum' started by cruz_e36, Mar 14, 2013.

  1. cruz_e36

    Thread Starter New Member

    Mar 14, 2013
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    In my recent school project we will be using an electro-mechanical actuator(I believe a rodless actuator) to take samples from a soil box, my question is what kind of signals does it give back for position/force? We will be using an arduino for this project, any feedback would be greatly appreciated, thanks!

    Cruz_ε36
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    Welcome to AAC!

    I found this thread moderated. I have approved it. It is a frequent problem for new posters (as in 1st time).
     
  3. John P

    AAC Fanatic!

    Oct 14, 2008
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    Most likely it's a potentiometer, but you're really asking us to be clairvoyants. We don't know anything about this device.
     
  4. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    post a link to the device you intend to use.
    If you haven't picked on then you need to define the specifics about how you intend to use this mysterious device.
     
  5. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Force applied feedback can be a huge area.

    Simple: Current load to motor driving sensor (rod)
    Complex: strain gauge to determine amount of force applied to rod for movement.
     
  6. cruz_e36

    Thread Starter New Member

    Mar 14, 2013
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    Here are some potential candidates we are considering,
    http://www.kollmorgen.com/en-us/products/linear-positioners/rodless-positioners/r4-series/
    http://www.kollmorgen.com/en-us/products/linear-positioners/rodless-positioners/r2a-series/
    http://www.kollmorgen.com/en-us/products/linear-positioners/rodless-positioners/r3-series/

    cruz_ε36
     
  7. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    the actuator itself gives NO feedback. It depends on which motor you use. For example with a stepper you need a rotary encoder,etc... along with it to get any definite position feedback. And then like thatoneguy said motor current/strain gauge,etc.. for force.

    Not sure whats involved in "take samples from a soil box" so I'm not sure why you need any feedback. Just tell the motor to move X steps to go a certain distance and away it moves.
    With steppers proper mechanical design,etc.. basically eliminates the need for position feedback.
     
  8. cruz_e36

    Thread Starter New Member

    Mar 14, 2013
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    My question is how will we get feedback in order to ensure that it has moved X steps? The actuator will only simply go down and from there we will have probes with vacuum pumps to suction out the contaminant.
     
  9. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    If you actually need position feedback then...
    If you use a stepper you need to also use an encoder. (numerous tutorials/examples with the arduino on how to do this)
    If you use a servo motor it typically already has an encoder for position feedback.

    Of course there are thousands of products using stepper motors without encoders/feedback and they work just fine. And again proper mechanical design and choice of steppers and you don't need feeback. We have a cnc controlled soldering machine that uses steppes for X,Y,Z axis movement and it runs all day without any feedback. We just tell it to move x steps and it does without missing a step. Of course when you start it it performs a "homing" procedure to ensure it knows where it is at the beginning. If you read about the actual motors that can attach to the actuators you linked above you would see that their servos offer numerous options for feedback.

    but again.. if you use steppers a simple homing procedure is probably all you need. Then just tell it to move 100 steps or whatever into the bucket.. turn on the vacuum, then tell it to move 100 steps in the other direction.
     
    Last edited: Mar 15, 2013
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