On a rational transfer function-based approach to ℋ∞ filter design for time-delay linear systems

This paper considers the problem of H
_∞
filter design for time-delay systems. An LTI finite dimensional system, called comparison system, is constructed in order to exploit recent results on stability analysis and H
_∞
norm calculation, which were proven to be strongly related to those of time-delay systems. Differently of what can be viewed as a common feature of filter design methods available in the literature to date, the one presented here addresses time-delay systems filtering with classical numeric routines based on Riccati equation and H
_∞
theory of LTI systems. The design algorithm is simple, efficient and easy to implement. An illustrative example is solved and is used to put in evidence the most important characteristic of the design procedure.