I am using the system identification tool box to create a greybox model. My error is The sizes of the matrices returned by the ODE function must be consistent with the input/o

1 view (last 30 days)
  7 Comments

Sign in to comment.

Accepted Answer

Rahul
Rahul on 4 Oct 2024
Hi @Yilin,
From what I understand, you are trying to create a linear ODE grey-box model using the state space matrices returned from your ODE function “GreyBox18”.
For a generic state space system, the state space equations are represented as follows:
Hence, as pointed out by @Torsten, since LHS of eq (1) has dimensions (3,1), the resultant of matrix multiplication of ‘K.*e(t)’ should also have (3,1) as its dim. So, it might be that the matrix ‘K’ needs to be initialized with size (3, 1), since error matrix ‘e(t)’ is a scalar. Here is how you structure your ODE function:
function [A,B,C,D,K] = GreyBox18(C_n, C_en, C_m, R_en, R_mn, R_oen, ~[AJ1] )
A = [(-1/(C_n*R_en)-1/(C_n*R_mn)), 1/(C_n*R_en), 1/(C_n*R_mn);
1/(C_en*R_en), -1/(C_en*R_oen)-1/(C_en*R_en), 0; 1/(C_m*R_mn), 0, -1/(C_m*R_mn)];
B = [1/C_n, 1/C_n, 0, 0, 0, -1/C_n;
0, 0, 1/(C_en*R_oen), 1/C_en, 0, 0;
0, 0, 0, 0, 1/C_m, 0];
C = [1,0,0];
D = zeros(1,6);
K = zeros(3,1); % Change size of K to (3,1)
end

More Answers (0)

Categories

Find more on Linear Model Identification in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!