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FAQ (Frequently Asked Questions)
Category:
CDS 101/110 Fall 2004
Identifiers: H0 H1 H2 H3 H4 H5 H6 H7 H8 L0.0 L1.1 L1.2 L2.1 L2.2 L2.3 L3.1 L3.2 L4.1 L4.2 L5.1 L5.2 L6.1 L7.1 L9.1
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For 2a, what do you mean by "less negative phase"?
Submitted by: asa
Submitted on: November 29, 2004
Identifier:
H8
Recall that 360 degrees of phase is the same as zero. The Bode plot of the new transfer function should have an identical magnitude section, but the phase should be closer to zero (modulo 360 degrees) than the phase of the given transfer function.
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How does settling time relate to the root locus plot?
Submitted by: asa
Submitted on: November 29, 2004
Identifier:
H8
If you look back at slide 7 from lecture 8.2, you'll see that you can learn about the settling time from the dominant poles. You should be able to see those poles on a root locus, and see how they move, which changes the settling time.
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What's the difference between calculating the tracking error with mag(L) vs. the sensitivity function?
Submitted by: asa
Submitted on: November 29, 2004
Identifier:
H7
, H8
For exact calculations of the frequency at which the error is less than a certain bound, you should use H_{er}, the sensitivity function. This gives you a measure of the error directly related to the input. The magnitude of L can be used as a quick approximation -- generally, 1/(1+mag(L)) will be close to mag(1/(1+L)). However, for precise work (i.e. not approximations), you should use H_{er}.
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