Unknown inputs observers design for delay systems

This paper concerns the design of functional, reduced and full order observers for linear time delay systems with unknown inputs. A new method generalizing those existing in the literature is presented for systems with unknown inputs, these unknown inputs are present in both the state and the measurement equations. Conditions for the existence of these observers are given and sufficient conditions for the stability independent of delays are derived using linear matrix-inequality (LMI) formulation. The independent of internal delay and independent of delay cases are also presented. A numerical example is presented to illustrate our approach.