Is there a difference between step response of a first-order transfer function and open loop step ?

Discussion in 'Homework Help' started by ASToonBlue, Mar 19, 2016.

  1. ASToonBlue

    Thread Starter New Member

    Mar 19, 2016
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    Is there a difference between step response of a first-order transfer function and open loop step response?
    I was asked to state if there is a difference between these 2 responses but
    Both response seems to be the same to me.
    [​IMG] [​IMG]
     
    Last edited: Mar 19, 2016
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,387
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    Does open loop have a limit?
     
  3. MrAl

    Well-Known Member

    Jun 17, 2014
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    Hi,

    Is there any other information other than just the two response curves?
    I ask because usually they are not the same but these appear to be very much the same.
    If we impose one graph onto the other we see they closely match, so without any other information they look the same. See attachment.

    In the attachment, one image is stretched and superimposed onto the other but displaced slightly lower and slightly to the right so we can still see the first image. The second image also has its plot color changed to red. It is hard to see, but the scales for both plots are the same.

    Using graphics is not the best way to compare. What did you do so far and is there a circuit with this?

    ControlPID_03.gif
     
  4. ASToonBlue

    Thread Starter New Member

    Mar 19, 2016
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    0
    Actually this is a theory question from the lecture note and the graph that I use is actually from the web since both look the same(about the same as the one in my lecture note as well)

    So I am wondering if there is a difference between the 2? What should I look out for in this case? Time constant? rise time?
     
  5. Papabravo

    Expert

    Feb 24, 2006
    10,138
    1,787
    You're asking for an apples to oranges comparison.
    To clarify you question:
    1. Is the first order system transfer function also open-loop?
    2. Is the open-loop system also first order?
    Why do you think these two things are different? Could ask your question more precisely?
     
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