Problem using IDSS command

Hi Everyone: I am using the 'idss' command for my project which is "Fault Detection in UAVs" and to add the fault vector in my state space I am using the 'idss' command. But the problem arises when I try to calculate the output of the state space using 'lsim' it does not seem to work with 'idss' and gives the error: For multi-input multi-output (MIMO) models both input and output indices must be given. What is the problem? Also is there any other way by which I can add fault vectors in state space? My Code is: A=[-0.64 1.51 -22.95 9.78 0 -4.19 -20.63 9.93 0 0 0.68 -2.68 -1.04 0 0 0 1.00 0 0 0 0 0 1.00 0 0];

B=[-1.25 3.19 -109.84 1.98 -4.33 -20.17 0 0 0 0]; C=[0.04 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1]; D=zeros(5,2); sys=idss(A,B,C,D,ones(5,5)); [y]=lsim(sys,u,t,zeros(5,1));

[Sebastian Castro]

I tried running your code (uses zero inputs since those weren't provided) and it runs fine for me.

A = [-0.64 1.51 -22.95 9.78 0; -4.19 -20.63 9.93 0 0; 0.68 -2.68 -1.04 0 0; 0 1.00 0 0 0; 0 0 1.00 0 0];
B = [-1.25 3.19; -109.84 1.98; -4.33 -20.17; 0 0; 0 0];
C = [0.04 0 0 0 0; 0 1 0 0 0; 0 0 1 0 0; 0 0 0 1 0; 0 0 0 0 1]; 
D = zeros(5,2);

t = 0:100;
u = zeros(101,2);

sys = idss(A,B,C,D,ones(5,5)); 
[y,t] = lsim(sys,u,t,zeros(5,1));
plot(t,y)

What exactly is the issue you are running into? I'm guessing you are defining the "u" and "t" vectors in a different way, and that's causing the errors you see.

[Qandeel]

Nope. I defined t=0:50; u=ones(length(t),2); but still getting the same error, can it be due to the version of MATLAB I am using, I am using R2009b!!

[Sebastian Castro]

I see... are you able to convert this to a regular SS (from Control System Toolbox) to do your simulation?

    >> sys2 = ss(sys)