MATLAB: PID controller in simulink

pidsimulink

Hi everyone! I am working on PID controller. I am having a model in simulink which I have uploaded at http://tinypic.com/view.php?pic=15cyg2&s=6. The gains of PID are: kp=1,Kd=1,ki=1.Saturation block has limits equal to -30 & +30. The state-space model has A=[0 1 0 0; 0 3.5 -106.5 0.37;0 0 0 1;0 0.21 -6.3 1.59]; B=[0 0;48.06 46664; 0 0; 340.18 47.7]; C=[1 0 1 0]; D=[0 0] and initial condition equal to 0. The system should converge at 20 as input is 20. But the problem is firstly its not converging and secondly the input of PID which is error signal appears as it is; as output with no modification. Need urgent help?

Best Answer

The problem can be sorted out if we use Ziegler-Nichols Tuning of PID controller.
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