Suppose that you want to linearize the plant P about an equilibrium operating point of the
model.To linearize only the plant, you open the loop at the output of block P. If you do not open
the loop, the linearized model between U and Y includes the effect of the feedback loop.Loop open at Y? Transfer Function from U to Y
Yes Ps
No P(s)
1+P(s)C(s)The loop opening does not have to be in the same location as the linearization input or
output point. For example, the following system has a loop opening after the gain on the
outer feedback loop, which removes the effect of this loop from the linearization. As a
result, only the blue blocks are on the linearization path.2 Linearization