2. Unit feedback systems subjected to a STEP input Type0” system: eee= lim sE(s)=lims ≠0 s-0 →0 1+ K∏I(s+2)S1+ K∏z1+K STI(S+p) Ks RIIz Type“” and higher systems: e= lime(s)=lims =0 s-0 s01K∏(s+z) =lim Klz 1+oo S 5-0 sTI(s+p,) IStep input can be tracked by systems of types I and higher!