Block Diagram Reduction: Steps to Find Closed Loop Transfer Function

[cd19]

1. Homework Statement

2. Homework Equations

I need to reduce the above block diagram to find the closed loop transfer function

This is my solution to the reduction part of the problem:

i) Add the feed forward paths; (10 + 10)

ii) cascade G(s)2 x G(s)3 , {G(s)2 = 1/1+12, G(s)3= 20/s}

iii) Reduce the minor feedback loop (0.2s) : using, G(s)/1+G(s)H(s) [G(s) being part ii]

iv) then finally cascade blocks in forward path

3. The Attempt at a Solution

This should be my open loop transfer function and from there I can get closed loop BUT I'm getting something wrong in my above reduction which I can't figure out. Anyone see where I'm going wrong?

 

[cd19]

Can anyone help me out

this is the answer for the closed loop function

 

[trapti54]

first convert the 3-input summation into two 2-input summation.
and after that i will become very easy to solve

 

[LabGuy330]

This question was asked in May 2011.

Hopefully it was solved by now.

But yes I agree with trapti once you separate the middle summing junction into two it is very simple.

 

[DeeNos]

I would first like to commend you for taking the time to attempt the problem and seeking help when you encountered difficulties. It is important to remember that problem-solving is an iterative process and sometimes it takes multiple attempts to arrive at the correct solution.

In terms of your solution, I would suggest double-checking your calculations and equations to make sure they are correct. It is possible that you made a mistake in one of the steps, which is why you are not getting the correct result.

Additionally, I would recommend using a systematic approach to block diagram reduction, such as the Mason's gain formula or the signal flow graph method. These methods can help you identify and eliminate any errors in your solution.

Lastly, it is always a good idea to double-check your final result by comparing it to a known solution or using simulation software. This can help you identify any discrepancies and fine-tune your solution.

I hope this helps and good luck with your problem-solving!