Creating and Manipulating Models

Using LTI Models in the Control System Toolbox

You can manipulate TF, SS, and ZPK models using the arithmetic and model interconnection operations described in Operations on LTI Models and analyze them using the model analysis functions, such as bode and step. FRD models can be manipulated and analyzed in much the same way you analyze the other model types, but analysis is restricted to frequency-domain methods.

Using a variety of design techniques, you can design compensators for systems specified with TF, ZPK, SS, and FRD models. These techniques include root locus analysis, pole placement, LQG optimal control, and frequency domain loop-shaping. For FRD models, you can either:

• Obtain an identified TF, SS, or ZPK model using system identification techniques.
• Use frequency-domain analysis techniques.

Other Uses of FRD Models

FRD models are unique model types available in the Control System Toolbox collection of LTI model types, in that they don't have a parametric representation. In addition to the standard operations you may perform on FRD models, you can also use them to:

• Perform frequency-domain analysis on systems with nonlinearities using describing functions.
• Validate identified models against experimental frequency response data.

LTI Models

LTI Objects