10.3. Cascade-Control Analysis

There are two common ways to represent a cascade-control system in transfer function form: series cascade and parallel cascade. The series cascade representation shown in Figure 10-8 is the most common, so it will be used in the analysis performed in this section. Students interested in analysis using the parallel structure can work Exercise 11.

Figure 10-8. Series cascade structure.

We use the following algebraic manipulations to understand the effect of the secondary (inner-loop) on the primary (or outer) loop. Notice that the secondary output can be written

Equation 10.1

The secondary closed-loop transfer function ...

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