4.2 Root Locus Concept The root locus is the path of the roots of the characteristic equation traced out in the complex -plane as a system parameter is changed Consider a unity-feedback closed-loop control system shown below We want to trace the roots of the characteristic equation of the system as the gain varies. The transfer function is R(S K G T(s) 1+ KG(s (4.1) 2022-2-3 32022-2-3 3 4.2 Root Locus Concept ¨ The root locus is the path of the roots of the characteristic equation traced out in the complex -plane as a system parameter is changed. ¨ Consider a unity-feedback closed-loop control system shown below. ¨ We want to trace the roots of the characteristic equation of the system as the gain varies. The transfer function is (4.1)