Example K G,(S) +1 Approximate Inverse without time-delay ≈ aS +1 1+st K K(a+2) Filter Approximate G(s= 1-Cs/2 2s+1 1+CS/2 PID G(S) (1+as/2)(1+sz)(1+as/2)(1+sr) K(a+n+ads/2)s K(a+n)Example s p e s K G s      1 ( ) Inverse without time-delay K s G s m 1 ( )     Filter 1 1 ( )   s G s f  Approximate e s s      1 K s s G s c ( ) 1 ( )       PI 1 / 2 1 / 2 s s e s        Approximate K s s s K s s s s G s c ( ) (1 / 2)(1 ) ( / 2) (1 / 2)(1 ) ( )                  PID  f m m f m c G G G G G G     1