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## Re: help with code system response state space

 From: Doug Stewart Subject: Re: help with code system response state space Date: Tue, 9 Jan 2018 09:23:28 -0500

On Tue, Jan 9, 2018 at 6:20 AM, Beginner1 wrote:
Hi!
I am a very beginner in Octave. I need your help in the following task:
I need to obtain and plot the step response of a system whose state-space
matrices are known and it can be represented by

xdot=A*x+B*u
y=C*x+D*u

For this purpose, I have written this code:

/%State-space system parameters
w=314.159;
ki=1.5;
kp=5000;
A=[0 1 0 0 0 0; 0 0 1 0 0 0; 0 -4*w^2 0 0 0 0;0 0 0 0 1 0;0 0 0 0 0 1;0 0 0
0 -4*w^2 0];
B=[0 0 0 0 0 0; 0 0 0 0 0 0;0 0 -1 0 1 0;0 0 0 0 0 0;0 0 0 0 0 0;0 0 0 -1 0
1];
C=[2*(w^2)*ki  0  ki  0  ki*w  0;0 ki*w 0 2*(w^2)*ki 0 ki];
D=[1 0 -kp 0 kp 0;0 1 0 -kp 0 kp];

%Perform system simulation

stname = {'xd1', 'xd2', 'xd3','xq1','xq2','xq3'};
sys = ss (A, B,C,D,'stname', stname)
t=linspace(0,3,1000)
[y,t,x]=step(sys)
plot(t,y)

/
However, an error message is obtained at the console for the command
plot(t,y) saying that the dimensions of one of the plot arrays are not
correct.

Any suggestion?

Thanks

did you try

step(sys)

DAS