A Non-Conservative Stability Criterion for Networked Control Systems with time-varying Packet Delays

TL;DR

This paper introduces a new stability criterion for networked control systems with time-varying packet delays, applicable with or without packet numbering, enhancing robustness analysis.

Contribution

It presents a non-conservative stability criterion based on the small gain theorem that covers cases with and without packet numbering or synchronization.

Findings

The criterion effectively handles time-varying delays in networked control systems.

Simulation shows improved stability assessment compared to existing methods.

Optimal delay design enhances control robustness.

Abstract

A networked output feedback loop subject to packetized transmissions of the output signal is considered. Based on the small gain theorem, an easy-to-use stability criterion covering two important cases is presented. In the first case a packet numbering mechanism is employed whereas in the second case neither packet numbering nor synchronization between sender and receiver is assumed. The analysis makes use of acausal subsystems and deduces the optimal constant time delay that should be used in a nominal controller design such that additional packet delay variations introduced by the network are maximized. A simulation example of a networked control system with a filtered Smith predictor illustrates the application of the proposed criterion and compares the results to different approaches from literature.