A block diagram reduction

[mech-eng]

I would like to ask why cannot I think G5 in series with G3(G4+G6G7) and then after muliplying them why I cannot think of G5*G3(G4+G6G7) in parallel to G2 so sum G2 and G5*G3(G4+G6G7) ?

Thank you.

 

[mfb]

If you do that, what happens to G₈ and C(s)?

G₅ would be at the other side, by the way.

 

[phinds]

I would like to ask why cannot I think G5 in series with G3(G4+G6G7) and then after muliplying them why I cannot think of G5*G3(G4+G6G7) in parallel to G2 so sum G2 and G5*G3(G4+G6G7) ?
.

I suggest you review the definitions of serial and parallel and see how they apply in this case. It's completely clear from the definitions that what you want to be series isn't series.

 

[mech-eng]

If you do that, what happens to G₈ and C(s)? G₅ would be at the other side, by the way.

If you do that I would ignore the multiplication of G₈ and G₅ so the result would be incorrect. I cannot think of what happens to the C(s) ? Is that the same thing for G(8) i.e ignorance of multiplication? But problem is that is G₅ also series with C(s) so when multiply G₅ with G₈ and (G₄ +G₆G₇) should I also multiply G₅ with C(s) ?

Thank you.

 

[mech-eng]

I suggest you review the definitions of serial and parallel and see how they apply in this case. It's completely clear from the definitions that what you want to be series isn't series.

I try to still understand. Because there is a common point between G₅, G₈ and (G₄ + G₆G₇), G₅ cannot be only series with (G₄ + G₆G₇) and the signal G₅ is going to both G₈ and (G₄ + G₆G₇) so G₅ is both series with them. When I do this result is correct but I think simpler.

Thank you.

 

[mfb]

You can make multiple G5 blocks, but I don't think that makes it simpler.

 

[mech-eng]

You can make multiple G5 blocks, but I don't think that makes it simpler.

But if I do that, I can get rid of rational expressions so I can write transfer function easily.

Thank you.