a012可，me-+gaf a5V1-52 2.0 1.8 When a=oo,the curve is a 0=1 1 14 0=2 standard step response of 0=3 a second order system, 1.2 号 1.0 just as zero does not exist. 0.8 0=∞ 0.6 The addition of a zero: 0.4 Maximum overshoot'个 0.2 Rising timev,peak time 0 2 6 7 8 @,When a=, the curve is a standard step response of a second order system, just as zero does not exist. ) 1 1 sin( 1 1 1 ( 2) ( ) 1 2 2 2 1 2 2                    a a e t tg a a a c t n t n The addition of a zero: Maximum overshoot Rising time, peak time