Hi all, I am trying to tune a PID using the Ziegler NIchols method, here is the transfer function :
And if I zoom in the waveform looks like this :
Which look nothing alike the waveforms I have seen online. Now if I increase my Kp above 1.8 the response of the system looks like this :
Now my question is: what am I doing wrong ? If I use that value for Ku=1.745 and continue with the calculations the response looks like this :
Which looks pretty wrong. So what I am doing wrong ? also if i try in matlab to plot the system response i get this plot :
Below is my block scheme and step input settings :