Error using fmincon MATLAB function in simulink

Hallo everyone,

I have this optimisation code which is simply maximize the volume of a cube within a surface are does not exceel 10 cm. but I have to run it in Simulink using MATLAB function block (as in the fig). there are two errors:

1- if i run the code as shown below: FMINCON requires 10 input arguments. Must set option Algorithm to 'sqp' and pass to solver.

2-if add coder.extrinsic('fmincon') below function y = fcn(x): Function handles cannot be passed to extrinsic functions.

Thanks in adevance

function y = fcn(x)

% L_G=1;
% W_G=1;
% H_G=1;
% X0=[ L_G  W_G H_G 5 6 ]
  X0=[x];
xopt=fmincon(@objective,X0,[],[],[],[],[],[],@contraints)

v=calcvolume(xopt)
a=area_surf(xopt)

function volume= calcvolume(x)
 L=x(1);
 W=x(2);
 H=x(3);
 
 volume= L*W*H
end 


function surface= area_surf(x)
 L=x(1);
 W=x(2);
 H=x(3);

surface = 2*L*H + 2*L*W + 2*W*H;
end

function obj =objective(x)
obj=-calcvolume(x)
end

function [c, ceq]= contraints(x)
c=area_surf(x)-10
ceq=[];
end

Answer 1

[Jesús Zambrano]

Hi Ayman,

Could you try the following:

function [v,a] = fcn(x)

myopts = optimoptions('fmincon','Algorithm','sqp');
xopt=fmincon(@objective,X0,[],[],[],[],[],[],@(x) contraints(x),myopts);

v=calcvolume(xopt);
a=area_surf(xopt);

I just specified v and a as the two outputs of the fcn function. Then, I used optimoptons command to create/modify optimization options and applied it to the fmincon. I got a=10 and v= 2.1517. See image enclosed.

Hope it helps!

[ayman mounir]

Hello Jesus,

thank you very much. it works.

[Kenneth Chijioke]

i have similar issues . i try to simulate fmincon in simulink but i am stuck . i make use of pv and battery system . then my non linear states predict are passed to my mpc controller containing my optimization , cost function and constrainsts but my output of my mpc is not changing it is just constant . that means my fmincon is not working