Optimal LQG Control of Networked Systems Under Traffic-Correlated Delay and Dropout

Abstract

Transmission delay and packet dropout are inevitable network-induced phenomena that severely compromise the control performance of network control systems. The realtime network traffic is a major dynamic parameter that directly influences delay and reliability of transmission channels, and thus, acts as an unavoidable source of induced coupling among all network sharing systems. In this letter, we analyze the effects of traffic-induced delay and dropout on the finitehorizon quality-of-control of an individual stochastic linear time-invariant system, where quality-of-control is measured by an expected quadratic cost function. We model delay and dropout of the channel as generic stochastic processes that are correlated with the real-time network traffic induced by the rest of network users. This approach provides a pathway to determine the required networking capabilities to achieve a guaranteed quality-of-control for systems operating over a shared-traffic network. Numerical evaluations are performed using realistic stochastic models for delay and dropout. As a special case, we consider exponential distribution for delay with its rate parameter being traffic-correlated, and trafficcorrelated Markov-based packet drop model.

Semantics- and Task-Oriented Scheduling for Networked Control Systems in Practice

“…We would like to mention that L * i is the optimal matrix minimizing the LQG cost F i without the consideration of the network. However, as the authors of [37] show in Corollary 1, the controller with the conditional state estimation as in ( 2) and the optimal feedback matrix L * i obtained by solving the standard LQG problem leads to the optimal control law as in (4) if the network is prone to delays and dropouts. The effects of the network imperfections are reflected in the estimation process.…”

Event-triggered sliding mode control for networked control systems with actuator faults: Application to gas turbine system

“…However, because of the addition of communication network, some thorny issues come one after another, which may impact the performance of the system or even lead to system instability, including transmission delay, packet dropouts, network bandwidth limitation, and so on. The effects of traffic-induced delay and dropout on the finite-horizon quality-of-control of an individual stochastic linear time-invariant system are analyzed (Maity et al, 2022). Time delay and packet loss are considered in the study of the linear quadratic regulation problem for discrete-time NCSs (Li et al, 2021).…”

A Sliding Mode Controller with Signal Transmission Delay Compensation for the Parallel DC/DC Converter’s Network Control System

“…Given the random occurrence of network transmission delays and packet losses, selecting and adjusting the signal sampling period for parallel DC/DC converters is a formidable challenge. This not only impacts the quality of the converter's output power but also hampers the overall control performance enhancement of the NCS [16,17].…”