This example explains therules that determine the type of model that results when you interconnect models of different types.
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.
For example, connect the ss model CL with a Control Design Block.
F = ltiblock.tf('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.