Event-triggered scheduling for stochastic multi-loop networked control systems with packet dropouts

In this paper, we study event-triggered data scheduling for stochastic multi-loop control systems communicating over a shared network with communication uncertainties. We introduce a novel dynamic scheduling scheme which allocates the channel access according to an error-dependent policy. The proposed scheduler deterministically excludes subsystems with lower error values from the medium access competition in favor of those with larger errors. Subsequently, the scheduler probabilistically allocates the communication resource to the eligible entities. We model the overall network-induced error as a homogeneous Markov chain and show its boundedness in expectation over a multi time-step horizon. In addition, analytical upper bound for the associated average cost is derived. Furthermore, we show that our proposed policy is robust against packet dropouts. Numerical results demonstrate a significant performance improvement in terms of error level in comparison with periodic and random scheduling policies.

I. Introduction

Control over shared communication resources imposes various imperfections, such as capacity limitation, congestion, time delays and packet dropouts, that impair the control performance and can even lead to instability. These network-induced phenomena give rise to the notion of Networked Control Systems (NCSs) [1]. In order to utilize the limited communication and energy resources in NCSs more efficiently, event-triggered control and scheduling strategies have been proposed recently [2]–[7].