Ciao, ho una domanda da porre: devo procedere alla linearizzazione di un sistema creato con una matlab function ma mi dà un errore sulla struttura degli stati di simulazione.

Lo script che utilizzo è il seguente:

% lo stato del sistema dinamico è dato da [z_eq;0;h_eq] dopo aver calcolato l'equilibrio del sistema.

z_eq=sqrt((0.2*i_eq)/(3*m*g))-1/3);

h_eq=((Kv+d)*(z_eq-K))^2/2*g*(Au)^2;

x_eq=[z_eq;0;h_eq];

u_eq=i_eq;

sistema_tc=linmod('progettoserbatoio',x_eq,u_eq);

il codice relativo alla matlabfunction che uso per costruire il foglio simulink progettoserbatoio è:

function [xdot,y]=fcn(x,u)

z=x(1); zdot=x(2); h=x(3);

xdot=[zdot; 0.2*i/(1+3*z^2)/m -g; (Kv*z - Kv*K)/At - Au*sqrt(2*g*h)/At];

y=x;

fatto run compare questo errore: error in linmod : the state of simulation must be specified as a vector of real doubles or a structure.

come risolvo?

si tenga conto che i valori di z_eq e x_eq risultano essere double complex.

Ringrazio anticipatamente per l'aiuto.

[Varun]

Hello! Can you please share the values of variables such as i_eq, Au, Kv, etc. in a MAT file? This will help me run the code on my end and investigate the issue. Thanks!

[GABRIELE CARULLO]

Yes, of course.

These are the values of parameters:

m=2; Kv=1; K=0.5; Au=0.004; At=0.3; i_eq=20 (corrente di equilibrio).

Thanks!!!

Answer 1

[Divit]

Hi Gabriele,

The linmod function is designed to accept state and input operating points for models that incorporate model blocks. Specifically, it anticipates the state argument to be either a vector consisting of real double-precision values or a structured data type.

The error in your code arises from the fact that the variable x_eq (representing the state) is not composed of real numbers but instead comprises complex numbers. This issue likely stems from the variable z_eq potentially being complex due to the utilization of the square root function when there is no real solution available.

It is advisable to carefully review the formula for the z_eq variable and ensure the correct usage of parentheses to properly handle complex solutions when needed.

To know more about linmod you can refer to the following documentation link:

• https://www.mathworks.com/help/simulink/slref/linmod.html

[GABRIELE CARULLO]

Hi!

All right, i will try your suggestion and updated land.

Thanks