Can you tell me what's wrong with the script I wrote for a Transfer function for a closed-loop feedback system with disturbances? Thank you.

This is the script I wrote for the transfer function for in the picture.

clear all;
figure;
for K = [5,10,50]
    Tnum=[K K 0];
    Tden=[1 16 21.5+K K+97.5];
    T=tf(Tnum,Tden);
    t=[0:0.1:10]; 
    [y,t]=step(T,t);
    plot(t,y); 
    hold on;
end
title('Unit Step Response for K= 5,10,50');
xlabel('Time(sec)'),ylabel('Step Response');
grid on;
grid minor;

I Know it is not correct because the output is not the same as the solution in the book. What am I doing wrong?

Answer 1

[Madhu Govindarajan]

If you look at your T it is a second order transfer function.

I think your Tnum should be [K K] and not [K K 0]

[Ashkhen Aristakessian]

Thank you Madhu. It is interesting because originally I did have [K K], but I kept getting an error message that the matrices were not matching... It works now...beats me. thanks a lot.