Configuring the worst-case communication delay in real-time networked control systems

Abstract

As a class of real-time systems, networked control systems (NCSs) are becoming increasingly significant in both fundamental investigations and industrial applications for effective integration of information, communications, and distributed computing and control. However, there are still challenging problems in this area. Two of the challenges are network-induced delay and jitter, and data packet dropout. The worst-case communication delay (WCCD) was conventionally treated as a constant for design of real-time systems and multi-task scheduling. This paper investigates some typical scenarios of real-time NCSs for understanding the behaviours of the network-induced delays. Then, from the nature of the distribution of the delays, an approach is developed to configure the WCCD for significant improvement of the system performance in real-time NCSs. It allows a certain level of packet loss rate to achieve a significant WCCD reduction. The packet losses are compensated through the strategies dealing with normal packet dropout.