What do I do wrong when using the stepplot command?
5 visualizzazioni (ultimi 30 giorni)
Mostra commenti meno recenti
Nico van der Aa
il 8 Gen 2022
Modificato: Nico van der Aa
il 13 Gen 2022
I have defined a first order system and a PI controller as follows:
and
In matlab code
tau = 0.1;
G_plant = tf(1,[tau 1]);
alpha = -0.1;
Gc = tf([1 alpha],[1 0]);
The controller should also have a gain value and I'm varying it from 0 to 10. My expectation is that, because of the PI-controller, the step response goes to 1 eventually for all gain values I choose. It does so, for gain values up to 8, but for a gain value of 9, I observe something strange. Could you help me explaining this phenomenon?
My code to draw the step responses for the PI-controlled system is
G_openloop = Gc*G_plant;
T = feedback(9*G_openloop,1)
stepplot(T);
Even if I compute the DC gain, it goes to 1, but the stepplot doesn't.
For the green line (K = 9) a strange bending of the curve occurs around time 2 seconds and the green line never goes to its steady state of 1.
0 Commenti
Risposta accettata
Pratyush Roy
il 11 Gen 2022
Hi Nico,
Although it might seem like the step response for gain values do not approach the steady state value of 1, this might be because it reaches steady state at a later stage due to the value of K chosen. To observe that, we can change the tFinal input argument for the stepplot command final time for step response computation to be a very high value, say 100.
Here is a script that illustrates how to change the tFinal value:
tau = 0.1;
G_plant = tf(1,[tau 1]);
alpha = 0.2;
Gc = tf([1 alpha],[1 0]);
K = 5:0.4:9;
for i=1:length(K)
G_openloop = Gc*G_plant;
T = feedback(K(i)*G_openloop,1);
hold on
stepplot(T,100);
end
hold off
Hope this helps!
1 Commento
Più risposte (0)
Vedere anche
Categorie
Scopri di più su Matrix Indexing in Help Center e File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!