Alternative frequency-domain stability criteria for discrete-time networked systems with multiple delays

In this paper alternative frequency-domain criteria are provided for the stability of discrete-time networked control 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∞ norm and the structured singular value. As a result, the obtained results can be used directly for controller synthesis via standard robust control techniques.