On design methods for sampled-data systems

In this paper we compare, via example, the standard approaches to sampled-data design with recently developed direct design methods for these hybrid systems. Simple intuitive examples are used to show that traditional design heuristics provide no performance guarantees whatsoever. Even when the sampling rate is a design parameter that can be chosen as fast as desired, using design heuristics can lead to either severe performance degradation or extreme over-design. These effects are apparently well-known to practitioners, but may not be widely appreciated by the control community at large. The paper contains no new theoretical results and is intended to be of a tutorial nature.