  With traditional open-loop scheduling of network resources, the
quality-of-control (QoC) of networked control systems (NCSs) may degrade
significantly in the presence of limited bandwidth and variable workload. The
goal of this work is to maximize the overall QoC of NCSs through dynamically
allocating available network bandwidth. Based on codesign of control and
scheduling, an integrated feedback scheduler is developed to enable flexible
QoC management in dynamic environments. It encompasses a cascaded feedback
scheduling module for sampling period adjustment and a direct feedback
scheduling module for priority modification. The inherent characteristics of
priority-driven control networks make it feasible to implement the proposed
feedback scheduler in real-world systems. Extensive simulations show that the
proposed approach leads to significant QoC improvement over the traditional
open-loop scheduling scheme under both underloaded and overloaded network
conditions.
