ABSTRACT
Numerical tools, e.g., Matlab, can be used to construct the root locus with respect to a parameter that appears nonlinearly in the characteristic polynomial. The purpose of this chapter is to examine how closed-loop system poles change as K varies from 0 to +∞, or from 0 to –∞. There are several software packages available for generating the root locus automatically for a given G1 = N/D. In particular, the related Matlab commands are rlocus and rlocfind. There are some situations in which controller gain can be negative as well. Therefore, the complete picture is obtained by drawing the usual root locus and the complementary root locus.
