Unknown input robust observers for time-delay systems

In this paper some conditions are given to design unknown input observers for time-delay systems. These observers are robust against disturbances, which is of great importance when some parameter changes or modelling errors can be modelled as an unknown input. A procedure to build a solution is developed and some simulation results are presented. A ring model for the linear time-invariant system with delays in state, inputs, outputs and disturbances, is considered.