Compare Performance of Multiple Designs

This example shows how to compare the performance of two different control system designs. Such comparison is useful, for example, to see the effects of different tuning methods or compensator structures.

Store First Design

In this example, the first design is the compensator tuned graphically in Bode Diagram Design.

After tuning the compensator with this first tuning method, store the design in Control System Designer.

On the Control System tab, in the Designs section, click Store. The stored design appears in the Data Browser in the Designs area.

The stored design contains the tuned values of the controller and filter blocks. The app does not store the values of any fixed blocks.

To rename the stored design, in the data browser, click the design, and specify a new name.

Compute New Design

On the Control System tab, tune the compensator using a different tuning method.

Under Tuning Methods, select PID Tuning.

To design a controller with the default Robust response time specifications, in the PID Tuning dialog box, click Update Compensator.

Compare New Design with Stored Design

Update all plots to reflect both the new design and the stored design.

On the Control System tab, click Compare.

In the Compare Designs drop-down list, the current design is checked by default. To compare a design with the current design, check the corresponding box. All analysis plots update to reflect the checked designs. The blue trace corresponds to the current design. Refer to the plot legend to identify the responses for other designs.

Tip

To add the legend to the plot, hover over the plot and click the legend icon.

To compare a stored design with the current design, the sample times of the current design and stored design must be the same. To modify the sample time of the current design to match that of a stored design, on the Control System tab, select Edit Architecture > Sample Time Conversion. Then, in the Sample Time Conversion dialog box, specify the sample time and a rate conversion method for each block in the architecture.

Restore Previously Saved Design

Under some conditions, it is useful to restore a previously stored design. For example, when designing a compensator for a Simulink^® model, you can write the current compensator values to the model (see Update Simulink Model and Validate Design (Simulink Control Design)). To test a stored compensator in your model, first restore the stored design as the current design.

To do so, in Control System Designer, click Retrieve. Select the stored design that you want to make current.

As with design comparison, to retrieve a stored design, the sample times of the current design and stored design must be the same.

Note

The retrieved design overwrites the current design. If necessary, store the current design before retrieving a previously stored design.