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- Thread starter QwertyXP
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meBigGuy

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I guess you could also analyse the loop performance in an open loop way by perturbing the input and looking at the response. This is commonly done. For example

http://www.mathworks.com/help/slcon...rol-system-for-stability-margin-analysis.html

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http://www.mathworks.com/help/releases/R2013b/slcontrol/ug/singleloop_control_block_diagram.png

The closed loop transfer function would be: Tc=C(s)P(s)/(1+C(s)P(s)) as per my understanding. However, couldn't we also make an open loop system having the same transfer function? e.g. an input X(s) goes into a block, and when it comes out, it is equal to X(s)Tc.

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meBigGuy

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meBigGuy

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http://www.cds.caltech.edu/~murray/books/AM05/pdf/am06-xferfcns_16Sep06.pdf has some stuff on page 256 about block diagram algebra. But it doesn't definitively answer your question. It sort of shows the feedback system as a component.

This ppt sort of addresses it the same way:

http://www.google.com/url?sa=t&rct=...HWqHdb_mMA0pNq1uAZcM70A&bvm=bv.53899372,d.cGE

Basically you can consider a closed loop system as an open loop component whose transfer function is the same as the closed loop system. You can then use this to combine complex multi-loop systems.

This ppt sort of addresses it the same way:

http://www.google.com/url?sa=t&rct=...HWqHdb_mMA0pNq1uAZcM70A&bvm=bv.53899372,d.cGE

Basically you can consider a closed loop system as an open loop component whose transfer function is the same as the closed loop system. You can then use this to combine complex multi-loop systems.

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