A Study of the Influence of Stochastic Fractional-Order Delay Dynamics in a Networked Control System

Stochastic communication delays are present in networked control systems and have a significant influence over its closed-loop performance and stability. These delays are time-variant and have infinite variance, indicating fractional-order behavior that can be modeled using alpha-stable distribution. This paper presents a quantitative analysis of the effects of fractional-order alpha-stable distribution random communication delays in a networked control system for a temperature control application. The networked closed-loop system assessment is performed using four different controllers. Two integer order PI controllers tuned using classic tuning methods, and two fractional-order PI controllers tuned using standard tuning rules for fractional-order system. One hundred numerical simulation experiments are performed, modeling the random communication delays between the plant and controller using an alpha-Stable distribution with different a values. Obtained results show that fractional-order controllers can deal better with time-variant fractional-order random communication delays that follows an alpha-Stable distribution compared with the integer-order controllers. Copyright (C) 2020 The Authors.