How to change C and D matrices of a state-space model?

Hi,

I created a state-space model with the Simulink Linearization Manager and would like to derive a model with fewer outputs. So far, however, my approaches have only led to errors:

A = eye(3);
B = ones(3,1);
C = [1 0 0; 0 1 0];
D = [0; 0];

sys1 = ss(A, B, C, D, ...
          'StateName', {'S1', 'S2', 'S3'}, ...
          'OutputName', {'O1', 'O2'});

sys2_C = [1 0 0];
sys2_D = 0;

sys2 = sys1;
%sys2.C = sys2_C;
% Error: The "C" and "D" matrices must have the same number of rows.

sys2 = ss(A, B, sys2_C, sys2_D, sys1);
% Error: Property "OutputName" must specify one name per output channel.

Is there an elegant way to create sys2 while keeping the properties (such as StateName) of sys1?

Answer 1

[Jesús Zambrano]

What about:

sys2 = ss(A, B, sys2_C, sys2_D, 'StateName', sys1.StateName)

[Dino]

Sure, this way is fine for the given example. However, if more fields are set (StatePath, StateUnit, Ts, InputName etc.), it would become a bit messy. So I think I should wrap the whole thing into a function.

[Jesús Zambrano]

sure, and get access to all the elements of sys1.