Custom objective function

[Ali Naderi]

Hi everyone,
I would like to just put the fist step of input prediction (u(0)) in the cost function. However I don't know is it possible to do it in simulink?

[Andreas Völz]

Dear Ali Naderi,

if I understand you correctly, you want to penalize only u(0) in the integral cost function and not u(t) for t in [0, Thor]. This is possible by adding if-statements in lfct, dldx, dldu, for example

void lfct(typeRNum *out, ctypeRNum t, ctypeRNum *x, ctypeRNum *u, ctypeRNum *p, ctypeRNum *xdes, ctypeRNum *udes, typeUSERPARAM *userparam)
{
    ctypeRNum* param = (ctypeRNum*)userparam;

    out[0] = (param[0] * POW2(x[0] - xdes[0])
            + param[1] * POW2(x[1] - xdes[1]) / 2;
     if(t == 0) {
            out[0] += param[2] * POW2(u[0] - udes[0])) / 2;
      }
}

void dldu(typeRNum *out, ctypeRNum t, ctypeRNum *x, ctypeRNum *u, ctypeRNum *p, ctypeRNum *xdes, ctypeRNum *udes, typeUSERPARAM *userparam)
{
    ctypeRNum* param = (ctypeRNum*)userparam;

    out[0] = (t == 0) ? param[2] * (u[0] - udes[0]) : 0;
}

Best regards,
Andreas Völz