Causality and Impulse Mode Freeness of an NDS with Descriptor Form Subsystems

A novel necessary and sufficient condition is derived in this paper for the causality/impulse mode freeness of a descriptor system. From this result, a matrix rank based necessary and sufficient condition is established for the causality/impulse mode freeness of a networked dynamic system (NDS) that is constituted from several descriptor subsystems, in which the associated matrix depends affinely on subsystem connections. A prominent property of this condition is that all the involved numerical computations are performed independently on each individual subsystem, which is quite attractive in reducing computation costs and improving numerical stability for large scale NDS analysis and synthesis. Situations have also been clarified in which NDS causality/impulse mode freeness is independent of subsystem connections.