I want to design an Internal Model Controller, but I have a non-linear system. Therefore I want to generate data from the non-linear model, to identify a linear model by the System Identification Toolbox from that data. (Because I want to set the model for the IMC as M=L+(N-L) so I only have to invert the linear model for control -> Q=inv(L))
Now my problem is that for the identified system D=0 (singular) so no inv() exist. So my question is if there is a possibility to identify a system with a nonsingular D ?