Optimal hold functions for MDCS sampled-data problems

In this paper the H2 and H∞ sampled‐data problems with mixed discrete/continuous specifications (MDCS) are considered. The hold function is not fixed a priory but rather is the design parameter. The (sub)optimal controller obtained is of the form of a serial interconnection of a (sub)optimal digital controller and a (sub)optimal hold function. It is demonstrated that the incorporation of the hold function into the sampled‐data design with MDCS extends considerably the possibility to reach a required trade‐off between discrete and continuous specifications in comparison with designs with a fixed hold function. Copyright © 2003 John Wiley & Sons, Ltd.