Plot Unity Feedback System in MATLAB

Question

Caitlin Hoying 2019-11-20

回答： Nicolas B. 2019-11-20

Looking for help on how to plot my equivalent feedback system. My model is (s+1) / s^2(s+2) + (s+1)(k-1).

I am looking off this model as an example, 500(s+2)(s+5) / (s+8)(s+10)(s+12), but am unsure about the technicalities.

%Matlab commands to plot system

nu=conv([1 1]);

de=conv([1 8],[1 10]);

de1=conv(de,[1 12]);

gs=tf(nu,de1);

ts=feedback(gs,1);

figure (1);step(ts);

grid on;

Thanks!

Answer 1

Nicolas B. 2019-11-20

If I understand correctly your question, you are trying to plot the step response of this function transfer:

Right?

Then, why not simply using the multiplication of transfer functions if you don't want to do the math?

% transfer function
H1 = tf(500, [1, 8]);
H2 = tf([1, 2], [1, 10]);
H3 = tf([1, 5], [1, 12]);
G = H1 * H2 * H3;
% show figure
figure;
step(G);