Time Delay Modeling and Sample Time Selection for Networked Control Systems

Abstract

This paper discusses the impact of network architecture on control performance in a class of distributed control systems called Networked Control Systems (NCS), and provides design considerations related to control quality of performance (QoP) as well as network quality of service (QoS). The integrated network-control system changes the characteristics of time delays between application devices. This study first identifies several key components of the time delay through an analysis of network protocols and control dynamics. The analysis of network and control parameters is used to determine an acceptable working range of sampling periods in an NCS. A network-control simulator and an experimental networked machine tool have been developed to help validate and demonstrate the performance analysis results, and identify the special performance characteristics in an NCS. These performance characteristics are useful guidelines for choosing the network and control parameters when designing an NCS.