Web Course Assignment 12

Web Assignment 12 Root Locus for PI-Controller
1. You got here. Good going! Today, it is root locus modeling to design a proportional-integral feedback controller.
2. We already have an Excel model built to do this. Download the model and load it into Excel.
3. Click on Root Locus plot for PI Feedback Model for FOPDT System
4. Fill in the parameters for your system: system gain (K), dead time (to) and first-order time constant (tau). Choose a value for the integral time constant (tau-sub-I). Then look at the graph. The graph should look something like this: If the Root Locus does not cross the y-axis, then you need to enlarge the value of Max-Kc (in column F, Row 1).
5. Find the value of Kc that is at the "breakaway" point. This is Kc for critical decay. Find the value of Kc that is at the "ultimate" point. This is Kcu Find the value of Kc that gives an imaginary value = 4.8 times the real value (This is shown in column "F" in the spread sheet). This is Kc for quarter decay. Repeat these steps for a lrger value of tau-sub-I and a smaller value of tau-sub-I.
6. Send an e-mail (report) within the next few days. (Click on "report" to get instructions.)

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contact Jim Henry - Lab-Master Send E-Mail to Jim Henry

Last revised 24 November 1997