Determine the transfer function of the block diagram

  • Engineering
  • Thread starter icesalmon
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  • #1
icesalmon
270
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Homework Statement:
Determine the transfer function of the block diagram
Relevant Equations:
Equations for Block Diagram Algebra
Step 1: I first started by reducing the inside of the block diagram of picture "bd" (the portion with G1 and the negative feedback G2)
I obtained G1/[1 + G1G2]
I'll call this term "F"

Step 2: Then I'm left with two terms feeding into a summing point:
F - G3
I'll call this term "K"

I can reduce this diagram as I did in the first step:

T(s) = K / [1 - K*G4 ]

The solution, on the other hand, is adding G3 to F as indicated in the second picture I've attached
"bd2"
I am not sure if this is a mistake (to add G3 instead of subtracting it) or if I'm not seeing something.
Any help is appreciated, apologies if I've left anything out or made my solution unclear in anyway.
 

Attachments

  • bd.PNG
    bd.PNG
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  • bd2.PNG
    bd2.PNG
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Answers and Replies

  • #2
Joshy
Gold Member
434
214
Has your class covered Mason's gain formula?
 
  • #3
icesalmon
270
13
No, we haven't covered that yet
 
  • #4
Joshy
Gold Member
434
214
Giving it another look... I personally agree with you with subtracting ##G_3##.
 
  • #5
icesalmon
270
13
Giving it another look... I personally agree with you with subtracting ##G_3##.
any luck? I think the solution is making a mistake.
 

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