Integrator does not accept input

Question

Andrei Rotaru 2024-6-23

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2131246-integrator-does-not-accept-input

评论： Sam Chak 2024-6-24

Hello, I'm trying make a model in simulink of an inverted pendulum and I can't simulate the space state. It's still telling me about that the integrator does not accept the input. Does anyone know what do to in this situation?

The formula that I'm trying to simulate:

Simulation:

The error:

Matlab code:

%%Parameters
Mp = 0.272;                      
dM = 0.071;                     
g = 9.81;                      
J = 0.002;                      
Jw = 3.941*10^-5;                
b_theta = 0.82*10^-3;           
b_altha_kmke_Ra = 1.202*10^-4;  
km_Ra = 1.837*10^-4;
%%Matrice
A = [0 1 0 0;
    (Mp*dM*g)/J -(b_theta)/J 0 1/J*b_altha_kmke_Ra;
    0 0 0 1;
    -(Mp*g*dM)/J b_theta/J 0 -(J+Jw)/(J*Jw)*b_altha_kmke_Ra];
B = [0 0;
    -1/J*km_Ra 1/J;
    0 0;
    (J+Jw)/(J*Jw)*km_Ra -1/J]
C = [1 0 0 0;
    0 1 0 0;
    0 0 1 0;
    0 0 0 0];
D = [0 0; 0 0;0 0;0 0];
%%Build system 
sys = ss(A,B,C,D);
x0 = [5*pi/180;0;0;0]; %initial condition for the integrator

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Answer 1

Sam Chak 2024-6-24

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2131246-integrator-does-not-accept-input#answer_1476041

Hi @Andrei Rotaru

The error is caused the mismatched matrix dimension. Do the following as shown in the graphics below should fix the issue. However, the built-in State-Space block can also perform the job equally.

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Andrei Rotaru 2024-6-24

Hi! Thanks a lot! It was very helpfull!

I need to do it manualy because I need the term x. And I don't know if i can extract it from the state space block individually.

Sam Chak 2024-6-24

在 MATLAB Online 中打开

Hi @Andrei Rotaru

If you wish to extract the state variables x, then only the state matrix equations

is necessary. First, the output and direct matrices must be constructed as shown below. Then, the individual state variables can be extracted using the "Demux" block.

A   = [zeros(3, 1), eye(3); zeros(1, 4)]
A = 4x4
     0     1     0     0
     0     0     1     0
     0     0     0     1
     0     0     0     0
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
B   = [0; 0; 0; 1]
B = 4x1
     0
     0
     0
     1
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
C   = eye(size(A))
C = 4x4
     1     0     0     0
     0     1     0     0
     0     0     1     0
     0     0     0     1
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
D   = 0*eye(size(A))*B
D = 4x1
     0
     0
     0
     0
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>