Example: Adding Upper Gain Limits :: SISO Design Tool (Using the SISO Design Tool and the LTI Viewer)

Using the SISO Design Tool and the LTI Viewer

Example: Adding Upper Gain Limits

This example shows you how to add two upper gain limit constraints to the open-loop Bode diagram. First, type

load ltiexamples
sisotool('bode',Gservo)

at the MATLAB prompt. This opens the SISO Design Tool with the servomechanism model loaded. Use the right-click menu to add a grid.

First, add an upper gain limit constraint of 0 dB from 10 rad/sec to 100 rad/sec. This figure shows the New Constraint editor with the correct parameters.

Your SISO Design Tool should now look like this.

Now, to constraint the roll off, open the New Constraint editor and add an upper gain limit from 100 rad/sec to 1000 rad/sec with a slope of -20 db/decade. This figure shows the result.

With these constraints in place, you can see how much you can increase the compensator gain and still meet design specifications.

Note that you can change the constraints by moving them with your mouse. See Editing Constraints for more information.

Design Constraints for Open-Loop and Prefilter Bode Diagrams Design Constraints for Open-Loop Nichols Plots