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自動控制與實驗

自動控制與實驗. Bode Plots. Advantage of Working with Frequency Response in terms of Bode Plots. Bode plots of systems in series (or tandem) simply add which is quite convenient. Bode’s important phase-gain relationship is given in terms of logarithms of phase and gain.

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自動控制與實驗

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  1. 自動控制與實驗 Bode Plots

  2. Advantage of Working with Frequency Response in terms of Bode Plots • Bode plots of systems in series (or tandem) simply add which is quite convenient. • Bode’s important phase-gain relationship is given in terms of logarithms of phase and gain.

  3. Advantage of Working with Frequency Response in terms of Bode Plots • A much wider range of system behavior (from low to high frequency behavior) can be displayed on a single plot. • Bode plots can be determined experimentally. • Dynamic compensator design can be based entirely on Bode plots.

  4. Bode Form of the Transfer Function • Bode form： all one • K0 is transfer function magnitude at very low frequencies.

  5. Classes of terms of transfer functions • (1) • (2) • (3)

  6. Class1:singularities at the origin

  7. Class2: first-order term • a) For • b) For • we call the break point • below: magnitude is approximately constant 1 • above: magnitude is like class 1

  8. Exp:

  9. phase • a) For • b) For • c) For

  10. Exp:

  11. Class3:second order term • Break point • Peak amplitude • magnitude change slop +40dB or -40dB • phase change +1800 or -1800

  12. Matlab’s Bode Plots • bode(num,den)

  13. Example: U0sinωt Y(t) G(s) Ĺ 1/(s2+s+3) U0 ω/(s2+ ω2)

  14. Result: (response of G(s)=1/(s2+s+3)to sint )

  15. Example: • KG1=10/s(s2+0.4s+4) • KG2=0.01*(s2+0.01s+1)/s2[(s2/4)+0.02(s/2)+1] numG=10 denG=[1 0.4 4 0] bode(numG,denG) numG=0.01*[1 0.01 1] denG=[0.25 0.01 1 0 0] bode(numG,denG)

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