Root Locus Plot Matlab

This kind of plot is sufficiently important that matlab has a command specifically for generating these plots.

Root locus plot matlab.

Rlocusgui is a graphical user interface written in the matlab programming language. Add the code k poles rlocfind c g1 onto the end of your m file to help you choose a specific loop gain. Thus we are limited to those responses that exist along the root locus. There is a method to do this with the rlocfind command in matlab.

Root locus design is a common control system design technique in which you edit the compensator gain poles and zeros in the root locus diagram. A root locus plot for this system is shown below along with the matlab used to create it. 1 as a first example consider the system which characteristic equation is as follows. A graphical method that uses a special protractor called a spirule was once used to determine angles and draw the root loci.

The root locus plot depicts the trajectories of closed loop poles when the feedback gain k varies from 0 to infinity. It shows the path of the roots as k is varied but does not show the actual values of k. The poles on the root locus plot are denoted by x and the zeros are denoted by o. A root locus plot is a variation on this kind of plot.

The root locus of an open loop transfer function is a plot of the locations locus of all possible closed loop poles with some parameter often a proportional gain varied between 0 and. As the open loop gain k of a control system varies over a continuous range of values the root locus diagram shows the trajectories of the closed loop poles of the feedback system. Both of the two feedback systems shown in figure 11 49are covered by this command. We can use matlab and its control system toolbox to plot the root locus of a control system given its characteristic equation or its forward transfer function.

Of course matlab can do this more accurately but it is important to know how pole and zero locations affect the final plot. It takes a transfer function and applies the standard rules for sketching a root locus plot by hand. After running in the command window go to the root locus plot and select a point near those indicated by the cross marks on the plot below. This video demonstrates how to obtain root locus of a given transfer function using matlab.