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How do robotic arms/joints know what position they are at?

  1. Aug 13, 2015 #1
    I guess I am interested in the various electronic means of finding out how a robotic joint relays positional information back to it's control unit.
     
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  3. Aug 13, 2015 #2

    BvU

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    Google position sensor
     
  4. Aug 13, 2015 #3

    Bystander

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    Can you constrain your question? Data formats from sensors? Sensor types?
     
  5. Aug 13, 2015 #4
    Bystander, I should let you know, I'm pretty unfamiliar with robotics. I guess, I am looking to create a small robotic arm, capable of being precisely manipulated. I am looking to familiarize myself with methods that will allow me to do this.

    Sensor type: something cheap and obtainable. Something that will fit into a relatively small rig.
     
  6. Aug 13, 2015 #5

    Bystander

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  7. Aug 13, 2015 #6

    berkeman

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    Welcome to the PF.

    Good advice! When I googled Rotational Position Sensor, the first non-ad hit on the list was this good introductory tutorial:

    http://www.electronics-tutorials.ws/io/io_2.html

    :smile:
     
  8. Aug 14, 2015 #7
    Stepper motors to move the joint could be used. In which case a feedback sensor to the controller could be used to verify position, but can also, and usually is, as operating from input from just the controller without feedback.
     
  9. Aug 18, 2015 #8

    donpacino

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    typically for robotic joints encoders will be used.
     
  10. Aug 18, 2015 #9

    Nidum

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    Problem is that a simple jointed arm robot is a bit like a new born donkey when you start it up - legs everywhere .

    One of the considerations when designing motion control systems is how to register the position of all moving components at start up . This means either using absolute encoders which always return the true position or simpler encoders which use a homing procedure to initialise position .

    Accurately positioning the working end of a jointed arm robot is not straightforward and can be very computer intensive .
     
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