How to realize a nlarx system in Simulink without using the Toolbox block

Hey all,

I am using System Identification Toolbox for constructing non linear ARX models. I already got nice nonlinear ARX systems which I named "motor_model_left" and "motor_model_right".

They have 6 nonlinear regressors: y1(t-1), y1(t-2), y1(t-3), u1(t), u1(t-1), u1(t-2).

I sent the systems to the workspace.

I also know, that nonlinear systems can be understood as an extension of a linear model. A linear SISO ARX model has this structure:

y ( t ) + a_1 y ( t - 1 ) + a_2 y ( t - 2 ) + ... + a_na y ( t - na )

= b_1 u ( t ) + b_2 u ( t - 1 ) + ... + b_nb u ( t - nb + 1 ) + e ( t )

(e(t) can be excluded)

My problem now is, that I don't know how to get the a and b coeffitients.

I need them because I have to create a Simulink model to simulate the motors without using the System Identification Toolbox blocks (in this case the Nonlinear ARX Model).

I already tried "motor_model_left.Nonlinearity.Parameters.LinearCoef"

and got: 0.3714, 0.0192, -0.0039, -0.0816, -0.0066, 0.0068 .

So I built a Simulink model seen in the png.

But that thing doesn't work. Either the coeffitients are wrong or my model.

Can somebody help me?

Thanks a lot!