PID - Root Locus (Sisotool) for Transfer Function (TF) with Zero and Poles in Right Plane

Discussion in 'MATLAB' started by Brian1776, Jul 11, 2021.

  1. Brian1776


    Jul 11, 2021
    Likes Received:
    Hi everyone! I have a 8th order transfer function, you can see it in the first image:

    % Transfer function
    num = [2.091,0,203.3,0,-2151,0,-1.072e05];
    den = [1,0,-830.4,0,-1.036e05,0,-5.767e05,0,2.412e07];
    tf = tf(num, den)


    I need to use a PID, so I'm trying to use a compensator, adding poles and zero with the sisotool in MatLab to turn it stable. But iI tried, I tried, and tried, without success. How you can see in picture bellow. But the zero on the right side always holds a pole.
    Note: Red zeros and poles have been added, and blue ones belong to the original transfer function.


    My question is:
    Is it possible stable this function adding zeros and poles, or not ?

    Any tips ?
    Note: I must use a PID for this lesson upload_2021-7-11_12-10-39.gif :(
    Brian1776, Jul 11, 2021
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