\[\begin{align*} \newcommand{\dif}{\mathop{}\!\mathrm{d}} \newcommand{\belowarrow}[1]{\mathop{#1}\limits_{\uparrow}} \newcommand{\bd}{\boldsymbol} \newcommand{\tx}{\text} \newcommand{\L}{\mathscr{L}} \newcommand{\p}{\partial\,} \end{align*}\]

概述

Fig. 8.1 shows a negative-feedback system.

• $H(s)$ is called the feedforward networks or jopen-loop transfer function
• $G(s)$ is called the feedback networks
• the input to $H(s)$ is $X(s)-G(s)Y(s), called the feedback error

The close-loop transfer function is

\[Y(s) = H(s) [X(s)-G(s)Y(s)]\\ \frac{Y(s)}{X(s)} = \frac{H(s)}{1+G(s)G(s)}\]