PIDesign:

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   Design a PI controller.

   Design a PI controller of the form

   y =  cx + du
   x =  ax + bu

   using pole placement. Inputs are the damping ratio and undamped natural
   frequency of the desired closed loop poles.

   If no outputs are requested then Bode plots for the controller will
   be drawn.

   To ensure that the gain at � is less than 1 make certain that

   2*zeta*wN*inr < 1

   Since version 1.
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   Form:
   [a, b, c, d, wC, k] = PIDesign( zeta, wN, inr, tSamp, sType )
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   ------
   Inputs
   ------
   zeta                Damping ratio
   wN                  Undamped natural frequency
   inr                 Axis inertia
   tSamp               Sampling period
   sType               State equation type ('Delta' or 'Z')

   -------
   Outputs
   -------
   a                   Plant matrix
   b                   Input matrix
   c                   Output matrix
   d                   Feedthrough matrix
   wC                  0 dB Crossover
   k                   Gain at infinity

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Children:

Common: Control/C2DZOH
Common: Control/C2DelZOH
Common: Control/FResp