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Homework Help: Transfer Function

  1. Sep 17, 2010 #1
    U(s) is my input, Y(s) is the output. I have two plants, G1(s) and G2(s). Between these two plants, i have a disturbance input, D(s).

    Am i right to say Y(s) = U(s)G1(s)G2(s) + G2(s)D(s)?

    If that is the case, how can i get the overall transfer function Y(s)/U(s)? Please advise. Thank you.
  2. jcsd
  3. Sep 18, 2010 #2


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    I believe if you move D(s) to the left, you will now have D(s)/G1(s) in parallel with G1(s) and G2(s).
  4. Sep 18, 2010 #3
    Hi rock.freak667,

    sorry i don't get you. do you mean shift the disturbance D(s) to the left of G1(s) as in in the block diagram?

    or do you mean the equation Y(s) - G2(s)D(s) = U(s)G1(s)G2(s)?

    please advise. thank you.
  5. Sep 18, 2010 #4


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    Sorry I was not clearer, I meant shift the disturbance to the left of G1(s) in the block diagram.
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