Root locus construction rules

Starting points K = 0) The root loei start at the open-loop poles. 

Termination points K = oo) The root loei terminate at the open-loop zeros when they exist, otherwise at infinity. 

Number of distinct root loci This is equal to the order of the eharaeteristie equation. 

Symmetry of root loci The root loei are symmetrieal about the real axis. 

Root locus asymptotes. For large values of k the root loei are asymptotie to straight lines, with angles given by 

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The construction rules for the root locus of a closed-loop system can be found in the books by Douglas [Ref. 12], Luyben [Ref. 7], and in the following two classic texts ... 

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