NONE 20260423100940732 wseas/wseas content-registration-form+ja@crossref.org content-registration-form WSEAS TRANSACTIONS ON SYSTEMS AND CONTROL 1991-8763 2224-2856 Nasri Amani Department of Electrical Engineering in LARATSI Research Laboratory, National Engineering School of Monastir (ENIM), University of Monastir, Avenue Ibn El Jazzar, Monastir 5019, TUNISIA Hamzaoui Fatma Department of Electrical Engineering in LARATSI Research Laboratory, National Engineering School of Monastir (ENIM), University of Monastir, Avenue Ibn El Jazzar, Monastir 5019, TUNISIA Khadhraoui Malek Department of Electrical Engineering in LARATSI Research Laboratory, National Engineering School of Monastir (ENIM), University of Monastir, Avenue Ibn El Jazzar, Monastir 5019, TUNISIA Ben Njima Chakib Department of Electrical Engineering in LARATSI Research Laboratory, National Engineering School of Monastir (ENIM), University of Monastir, Avenue Ibn El Jazzar, Monastir 5019, TUNISIA Messaoud Hassani Department of Electrical Engineering in LARATSI Research Laboratory, National Engineering School of Monastir (ENIM), University of Monastir, Avenue Ibn El Jazzar, Monastir 5019, TUNISIA This paper concerns an improved H∞ filter design for discrete-time linear singular uncertain systems with constant time delay and unknown input. The proposed approach yields a robust observer that reconstructs a state functional despite the presence of uncertainties that are functions of a bounded noisy signal. The uncertain quantities are considered as disturbances. H∞ filter is designed to attenuate the effect of parametric uncertainties on the estimation error and reconstructs a state functional independently of the actuator fault described by an unknown input vector. The proposed filter is based on the Krasovskii stability theory to ensure converging unbiased dynamics. The bias-free conditions are formulated into a convex optimization problem, leading to an optimal filter gain design. The results, validated on a benchmark numerical example and compared with existing methods, confirm the effectiveness of the proposed approach. 12 31 2025 12 31 2025 570 56 https://creativecommons.org/licenses/by/4.0/deed.en_US 10.37394/23203.2025.20.56 https://wseas.com/journals/sac/2025/b145103-1412.pdf T. Chevet, T. N. Dinh, J. Marzat, Z. 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