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Homework Help: Feedback Control Systems

  1. Mar 3, 2010 #1
    1. The problem statement, all variables and given/known data

    http://img24.imageshack.us/img24/9028/72841137.jpg [Broken]

    2. Relevant equations

    Routh-Hurwitz Stability Criterion

    3. The attempt at a solution

    For first question, you just write the Routh Array, make sure that the first row is all positive and you get Kmax = 1. Simple enough

    How would I approach the second question though? Any starters would be sincerely appreciated.
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Mar 4, 2010 #2


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    You got the value K = 1 by making the line [tex]s^1[/tex] equal to zero. Now, you form an auxiliary equation with the coefficients of the [tex]s^2[/tex] line. The roots of the auxiliary equation are also roots of the characteristic equation. Solve it and you get two imaginary roots, whose module is the oscillation frequency when K = 1.
    Last edited by a moderator: May 4, 2017
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