In this paper, we propose a reduced-order observer, for state estimati
on in a class of state-delayed dynamical systems driven by known as we
ll as unknown inputs. Conditions For existence of the proposed observe
r, plus the stability and convergence proof for the observer based on
the Razumikhin theorem are given. Additionally, the proposed observer
is utilized in an analytical-redundancy-based approach for sensor and
actuator failure detection problem in the same class of time delay dyn
amical systems. Finally, the applicability and effectiveness of the pr
oposed FDI scheme is illustrated through numerical examples. (C) 1998
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