On the modeling of networked controlled systems

In this article modeling approaches for networked controlled systems (NCS) with different types of varying communication latency times are presented. The embedded delays are unknown, bounded and depending on their size relative to the sampling period, four different models are offered. There is distinct treatment for delays longer than one sampling period, since these are decomposed to a term which is integer multiple of the sampling period and a residual which can be time-varying. The careful mixing of asynchronous (event-driven) and synchronized (sampled) signals can lead to discrete time uncertain and possibly switched systems, where classical control approaches could be applied.