Alternative Frequency-Domain Stability Criteria for Discrete-Time Networked Systems with Multiple Delays

In this paper alternative frequency-domain criteria areprovided for the stability of discrete-time networkedcontrol systems with time-varying delays. These criteria are in various situations less conservative than the existing frequency-domain conditions as is demonstrated by means of an example. In addition, new stability conditions are presented that allow for multiple sensor-to-controller and controller-to-actuator channels exhibiting different delay characteristics. The stability conditions are formulated in terms of the H_infinity norm and the structured singular value. As a result, the obtainedresults can be used directly for controller synthesis via standard robust control techniques.