This paper proposes a new digital redesign method for determining the hybri
d controller of a continuous-time system with input time delay using an obs
erver-based digital controller. The proposed method together with the genet
ic algorithms is used to determine: (1) the interval digital model of a con
tinuous-time uncertain System with input time delay, (2) the interval digit
al redesign control law and (3) the interval digital observer of the origin
al continuous-time uncertain observer with input time delay. Moreover, the
result is less conservative than those obtained by the existing interval me
thods. A discrete-time observer is built by the original continuous-time ob
server with input-time-delay control law and a predictor such that the esti
mated states of the redesigned discrete-time observer closely match those o
f the original continuous-time observer with input time delay not only at s
ampling instants but also the behavior of the system state during the sampl
ing interval is optimal by minimizing the hybrid performance index. The dig
itally redesigned observer-based controller can closely match the states of
the digitally redesigned uncertain sampled-data system with those of the o
riginal continuous-time observer-based controlled uncertain system with inp
ut time delay.