Analytic PID Design

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Analytic PID Design If G(s) is the loop gain, then the characteristic equation can be written as We want to find the value of k p , k d , and k i to place a pole of the characteristic equation at a specified location, s 1 . In other words, we want to find the value of s 1 that satisfies If we consider the controller Equation 1 but s 1 is also a complex number that can be represented by a magnitude and a phase: Rewriting equation 1 gives us Assume we can pick k i based on some other criterion, we can rewrite the equation Equating real and imaginary parts of this last equation gives us a set of two equations in two unknowns (since k i is known). Analytic PID Design file:///C:/Documents and Settings/Win XP/Desktop/Survey_PID/Lectur... 1 de 2 12/3/2012 22:33

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Analytic PID Design

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  • Analytic PID DesignIf G(s) is the loop gain, then the characteristic equation can be written as

    We want to find the value of kp, kd, and ki to place a pole of the characteristic equation at a specified location, s1. Inother words, we want to find the value of s1 that satisfies

    If we consider the controller

    Equation 1

    but s1 is also a complex number that can be represented by a magnitude and a phase:

    Rewriting equation 1 gives us

    Assume we can pick ki based on some other criterion, we can rewrite the equation

    Equating real and imaginary parts of this last equation gives us a set of two equations in two unknowns (since ki isknown).

    Analytic PID Design file:///C:/Documents and Settings/Win XP/Desktop/Survey_PID/Lectur...

    1 de 2 12/3/2012 22:33

  • If s1 and ki are known, they can be used to find M, q, B and b, and the equations can be solved for kp and kd. Doinga little algebra yields the general result that

    Analytic PID Design file:///C:/Documents and Settings/Win XP/Desktop/Survey_PID/Lectur...

    2 de 2 12/3/2012 22:33