Nowadays, in industrial control applications, is rather
usual to sample and update different variables at different rates,
although it is common to consider all these activities equally and
regularly spaced on time. These applications can be found, for
example, on real-time operating systems by decomposing them
into several tasks in such a way that pre-emption and blocking
may appear due to task priorities and resource sharing, or in
networked control systems, where due to the existence of large
distances and space limitations, several devices (controller,
process and others) share a common communication bus. In
both cases, these facts could imply the presence of limited
random delays, leading to a non-regular non-periodic behavior
and, as a result, the control performance can be degraded. In
order to undertake this problem, a solution based on a modeling
methodology for non-uniform sampled-data systems can be
utilized. This technique permits the consideration of any cyclic
sampling pattern. However, it can be adapted to deal with
limited random delays, and later on, a multi-rate controller
based on this model can be designed. In this way, if the
considered non-conventional control system is implemented, a
clear performance improvement can be observed.