Transient response with unit-step input +250n少+oy=ou(t) Roots are 2=-0n±0nV52-1 Rising monotone,without vibration,long transient reponse,can be divided as two first-order systems. 5>1 OverdampedRoots are  1 Overdamped 1 2 P1、2  n n   Rising monotone, without vibration, long transient reponse, can be divided as two first-order systems. Transient response with unit-step input 2 2 2 () nn n   y y y ut     