Rules That Determine Model Type

When you combine numeric LTI models other than frd models using connect, the resulting model is a state-space (ss) model. For other interconnection commands, the resulting model is determined by the following order of precedence:

ss > zpk > tf > pid > pidstd

For example, connect an ss model with a pid model.

P = ss([-0.8,0.4;0.4,-1.0],[-3.0;1.4],[0.3,0],0);
C = pid(-0.13,-0.61);
CL = feedback(P*C,1)

The ss model has the highest precedence among Numeric LTI models. Therefore, combining P and C with any model interconnection command returns an ss model.

Combining Numeric LTI models with Generalized LTI models or with Control Design Blocks results in Generalized LTI models.

For example, connect the ss model CL with a Control Design Block.

F = tunableTF('F',0,1);
CLF = F*CL

CLF is a genss model.

Any connection that includes a frequency-response model (frd or genfrd) results in a frequency-response model.

Note

The software automatically converts all models to the resulting model type before performing the connection operation.