Root locus plot of dynamic system
[r,k] = rlocus(sys)
r = rlocus(sys,k)
rlocus computes the root locus of a SISO
open-loop model. The root locus gives the closed-loop pole trajectories
as a function of the feedback gain k (assuming
negative feedback). Root loci are used to study the effects of varying
feedback gains on closed-loop pole locations. In turn, these locations
provide indirect information on the time and frequency responses.
and plots the root locus of the open-loop SISO model
This function can be applied to any of the following negative feedback
loops by setting
sys has transfer function
the closed-loop poles are the roots of
rlocus adaptively selects a set of positive
gains k to produce a smooth plot. Alternatively,
uses the user-specified vector
k of gains
to plot the root locus.
rlocus(sys1,sys2,...) draws the root loci
of multiple LTI models
sys1, sys2,... on a single
plot. You can specify a color, line style, and marker for each model,
[r,k] = rlocus(sys) and
r = rlocus(sys,k) return
k of selected gains and the complex
r for these gains. The matrix
jth column lists the closed-loop roots
for the gain
Plot the root-locus of the following system.
h = tf([2 5 1],[1 2 3]); rlocus(h)
You can use the right-click menu for rlocus to add grid lines, zoom in or out, and invoke the Property Editor to customize the plot. Also, click anywhere on the curve to activate a data marker that displays the gain value, pole, damping, overshoot, and frequency at the selected point.
You can change the properties of your plot, for example the units. For information on the ways to change properties of your plots, see Ways to Customize Plots.