Hey guys, I am designing a digital controller for my second order plant, its continuous open loop transfer function is as follows:
dens = [1 0.2606 0.4378];
Gpz = c2d(Gps, T, 'ZOH');
I am using a phase lead compensator, I arrive at the following controller discrete function:
Dz_lead = 10.2751*tf([1 -0.8196], [1 0.8541], T);
Plotting the step response of the controlled and uncontrolled systems (Gpz being the ZOH discretization mentiones before):
Cz_lead = feedback(GDz_lead, 1);
step(Cz, 'r', Cz_lead, 'g', 50);
legend('Uncompensed system', 'Phase lead compensation');
Both systems stabilze at the same amplitude, and the settling time improved greatly.
However, when using Simulink:
I get the following output (for a step input of 5):
Why does it fall short with respect to the input? The step function used previously says it shoud follow nicely, or do I need to add a proportional gain before the compensator every time?
