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Control Systems Engineering - Block Reduction Help

  • Thread starter GreenPrint
  • Start date
  • #1
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Homework Statement



Hello,

I'm trying to reduce the following block diagram

Capture.png


Homework Equations




The Attempt at a Solution



I appear to be having some issues in doing this. The first thing that I did to reduce this block diagram was to take the forward path that has 2/(s+4) with negative feedback of 2, and reduce this by

(K G(s))/(1 + K*G(s)*H(s)) = (3/(s+4))/(1 + 6/(s+4)) = 3/(s+4 + 6) = 3/(s+10)

I also moved the 1/s block to the left of the summation. This resulted in a parallel path with a gain of one. I reduced this to simply a forward path with 1/s + 1.

I then did the following with 6s and the negative feedback with a gain of 1

This resulted in a reduced diagram with

(1/s +1)*3/(s+10)

in the forward path with a negative feedback of 6s+1

I guess I have done something wrong, and I'm not exactly sure what. Below is a picture of what I did.

Untitled.jpg


Thanks for any help. I guess I'm doing something wrong, but am not exactly sure what it is I'm doing wrong.
 

Answers and Replies

  • #2
402
120
I also moved the 1/s block to the left of the summation. This resulted in a parallel path with a gain of one. I reduced this to simply a forward path with 1/s + 1.
When you did this, did you remember to adjust the 6s path as well? TBH I worked hard to forget all this stuff. But I'm pretty sure I got stuck on this exact question as well =D
Could you try moving the 1/s instead to the right? That way you'd only need to adjust the foward path 1 to S

You could also try moving the 6s into the 1 feedback, but would have to adjust that forward back then to 1-6s


I really hated these was always much better with the equations :)
 
  • #3
donpacino
Gold Member
1,439
282
I also moved the 1/s block to the left of the summation. This resulted in a parallel path with a gain of one. I reduced this to simply a forward path with 1/s + 1.
like cpscdave said there is your problem
 

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