Getting Started

Adjusting the Compensator Gain

Figure 4-5 shows that the closed-loop step response is too slow. The simplest approach to speeding up the response is to increase the gain of the compensator. To increase the gain:

1. Move the mouse pointer over the Bode magnitude line. Notice how the pointer becomes a hand.
2. Grab the Bode magnitude line by holding down the left mouse button when the hand appears.
3. Drag the Bode plot line upward.
4. Release the mouse button. The gain and poles change as the closed-loop set point is recomputed.

The SISO Design Tool calculates the compensator gain, and the value appears in the C(s) text box on the GUI.

Alternatively, you can set the gain by entering the desired value in the C(s) field in the Current Compensator panel.

Right-Click Menus

The SISO Design Tool has right-click menus available in any of the plot regions. The menus are customized for each plot type; open the Bode magnitude menu by right-clicking your mouse in the white space of the Bode magnitude plot. This menu appears.

Figure 4-6: Right-Click Menu for the Bode Magnitude Plot

The right-click menus contain numerous features. The DC motor example makes use of many of the available features; for a complete discussion of the right-click menus, see the online help for the SISO Design Tool in GUI Reference.

Bode Diagram Design

Adjusting the Bandwidth