Event-based data scheduling for a class of interconnected networked control systems

In this paper we address the problem of event-based data scheduling for a class of physically interconnected networked control systems which compete for limited communication resources. The overall interconnected system consists of multiple heterogeneous LTI sub-systems with the physical interconnection being modeled by a directed acyclic graph (DAG). The sub-systems are controlled by a networked controller through a shared communication channel. In order to cope with the limited channel capacity, we introduce a bi-character deterministic-probabilistic scheduling mechanism which dynamically assigns access priorities to each sub-system at each time-step according to an error-dependent priority measure. The sub-systems which are granted channel access then transmit their state information through the communication network. Given an emulation-based control strategy, we prove stability of such networked systems under the proposed scheduling law in terms of f-ergodicity of overall network-induced error. Simulation results illustrate the proposed approach and show a reduction in the error variance compared to standard TDMA and uniform random-access scheduling policies.