考研851 自动控制原理
真题 · image

(2)

由几何关系计算

图:根轨迹渐近线示意图1

图:根轨迹渐近线示意图2

\[K^* = 16K = (\sqrt{2})^* \Rightarrow K = 0.25 \Rightarrow s = -1 \pm j; -3 \pm j\]

六、解答

(1)

\[G(z) = K\frac{z-1}{z}z\left\{\frac{1}{s(s+1)}\right\} = K\frac{z-1}{z}\left\{\frac{z}{z-1} - \frac{z}{z-0.368}\right\}\]
\[= K\left(1 - \frac{z-1}{z-0.368}\right) = \frac{0.632K}{z-0.368}\]

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