(Simulink/MPC) Unable to linearize with an if...else loop

I am trying to design an MPC Control for my project but it seems that the Simulink cannot linearize my model accurately due to the presence of an embe dded-MATLAB function block containing an if...else loop.

My model looks like this: (dunno how to upload photos. sry)

Embedded MATLAB -> Plant Model -> MPC--
^                                      |
|______________________________________|

And th function in the embedded MATLAB is

function EmbeddedMATLAB=Output(t,u)
% t = time and u= output from MPC Controller
if t<3
   Output=100;
else Output =u;
end

After designing the MPC Controller, the linearized result for the MPC Controller was 0. So how shlould i go about doing it?

Answer 1

[Erman Korkut]

Hi Tan,

The Embedded MATLAB function blocks are linearized using numerical perturbation by default. Your code seems to indicate that if you linearize your model at a time smaller than 3, the embedded matlab block's output is not a function of input u; instead it is fixed and thus its derivate is zero, thus linearizing to zero.

If you would like to specify a custom linearization for your Embedded MATLAB function block, you can right-click on it and select Linear Analysis->Specify Linearization. Then you can specify the linearization of this block.

Thanks, Erman