Two Conditions for Plotting root locus Given open-loop transfer function Gk(S) Characteristic equation K4(+ ∏(+p,) Magnitude Condition and argument Condition II(s+p) J=1 K ∠∑ (s+)-2∑(s+p1)=±(2k+1)z,k=012 i=1 S+Z 上潇人字 SHANGHAI ILAO TONG UNIVIRSITYTwo Conditions for Plotting Root Locus ( ) 1 1 ( ) 1 ( ) m g i i k n j j K s z G s s p = = + = = − +   Given open-loop transfer function Gk (s) Characteristic equation   = = + + = m i i n j j g s z s p K 1 1 | ( )| | ( )| ( ) ( ) (2 1) , 0,1,2.. 1 1  + − + =  + = = = s z s p k k n j j m i i  Magnitude Condition and Argument Condition