In Chapter 8, we saw that the root locus graphically displayed both transient response
and stability information. The locus can be sketched quickly to get a general idea of the changes in transient response generated by changes in gain. Specific points on the
locus also can be found accurately to give quantitative design information.
The root locus typically allows us to choose the proper loop gain to meet a
transient response specification. As the gain is varied, we move through different
regions of response. Setting the gain at a particular value yields the transient
response dictated by the poles at that point on the root locus. Thus, we are limited
to those responses that exist along the root locus.