Multirate sampled-data systems: all H∞ suboptimal controllers and the minimum entropy controller

For a general multirate sampled-data (SD) system, the authors characterize explicitly the set of all causal, stabilizing controllers that achieve a certain H_∞ norm bound; moreover, they give explicitly a particular controller that further minimizes an entropy function for the SD system. The characterization lays the groundwork for synthesizing multirate control systems with multiple/mixed control specifications