The relative stability and the transient performance of
a closed-loop control system are directly related to the location of
the roots of the characteristic equation in the s-plane. The locus of
roots in the s-plane can be determined by a graphical method.
The root locus technique is studied in this paper, it is a powerful
tool for designing and analyzing feedback control systems, .It is
possible to use root locus methods for design control system when
two or three parameters vary.
Keywords: locus of roots; graphical method; analyze; feedback
control systems