how to add a state space representation with identifiable parameters into a Matlab function or a any block?

Hello everyone,

I found a way to add the disturbances into the state space representation but I don't know how create a block for that,

so I have created a matlab function with the code,

function [SOC,LOH] = statespace(PH2,Pgrid,d)
A = [1 1;1 1];
B = [0.0936 0.0936;-0.339 0]; 
C = [1 1;1 1]; 
D = 0; 
K = [0.0936;0];
[SOC,LOH] = idss(A,B,C,D,K);
end

so the figure 1 is what i tried to do with the code above, and figure 2 is the state space representation with disturbances,

and the error is:

[Walter Roberson]

I wonder if it would help to use https://www.mathworks.com/help/control/ref/tunabless.tunabless.html ?

Answer 1

[Sam Chak]

Hi @kawsar

I'm unfamiliar with your system (probably something to do with the state of charge of an energy storage system).

However, the Output Matrix , because it implies both outputs are the same .

Please check the matrix equations again.

A   = [1 1;             % state matrix
       1 1];
B   = [0.0936 0.0936;   % input matrix
      -0.339  0];
C   = [1 1];            % output matrix
D   = zeros(1, 2);      % direct matrix
K   = [0.0936; 0];      % disturbance matrix
sys = idss(A, B, C, D, K)

sys =
  Discrete-time identified state-space model:
    x(t+Ts) = A x(t) + B u(t) + K e(t)
       y(t) = C x(t) + D u(t) + e(t)
 
  A = 
       x1  x2
   x1   1   1
   x2   1   1
 
  B = 
           u1      u2
   x1  0.0936  0.0936
   x2  -0.339       0
 
  C = 
       x1  x2
   y1   1   1
 
  D = 
       u1  u2
   y1   0   0
 
  K = 
           y1
   x1  0.0936
   x2       0
 
Sample time: unspecified

Parameterization:
   FREE form (all coefficients in A, B, C free).
   Feedthrough: none
   Disturbance component: estimate
   Number of free coefficients: 12
   Use "idssdata", "getpvec", "getcov" for parameters and their uncertainties.

Status:                                                         
Created by direct construction or transformation. Not estimated.
 

x0  = [0.1, 0.1];
Ts  = 0.1;
% sys = idss(A, B, C, D, K, x0, Ts)