MATLAB: How to plot Step response of MIMO system

mimoplotstep

I am working on MIMO system with following A,B,C,D matrix.

A=[3 4 -7;5 4 0;-5 -7 10];
B=[1 0;0 0;1 1];
C=[1 1 0;1 0 1];
D=zeros(2,2);
sys_OL=ss(A,B,C,D);
[y_OL,t]=step(sys_OL);

While finding the step response of system, I got the dimension of y_OL as 319 x 2 x 2 double;

How can I plot the output?

Best Answer

Hi,

if you use:

[y_OL,t]=step(sys_OL);

you get a matrix as result. To directly plot the step response use:

step(sys_OL)

Best regards

Stephan

Related Solutions

MATLAB: Conversion from State Space to TF and then back to State Space

Some points:

Don't do "algebra" with tf variables, use the functions series, parallel and feedback.

sys_mimo1 = ss(sys_mimo) is going to convert the tf model to a ss model, I don't think there is a need for the extra step with ssdata.

This one here

sys_mimo_tf(1,2) = sys_mimo_tf(1,2)*feedback(sys_mimo_tf(1,2),C);

is probably not doing what you want it to, it will give you the transfer function

sys_mimo_tf(1,2)^2 /  1 + sys_mimo_tf(1,2)*C

so that's probably where many extra states come from. You should expect 2 extra states per added PID.

Lastly, look at the Hankel Singular Values or a similar measure to figure out whether there might be a lot of almost unobservable/almost uncontrollable states in your resulting model. That would indicate numerical issues.

MATLAB: How can i plot transfer function with step signal input

You can multiplythem together and then use the impulse() function

s = tf('s');
G = 2/(s+2);
R = 2/s;
sys = G*R;
impulse(sys)

Best Answer

Related Solutions

MATLAB: Conversion from State Space to TF and then back to State Space

MATLAB: How can i plot transfer function with step signal input

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