Fault Detection of Distributed Networked Control Systems with Access Constraints

Abstract

This paper considers the fault detection problem of distributed networked control systems (DNCS) with limited data transmission rate. In order to deal with the limited bandwidth of the network, two steps are taken. The first one is the periodic communication sequence which is introduced to the two-level DNCS to ensure that only some specified subsystems rather than all of them are connected to the central fault diagnosis unit at a certain time; the second one is that the signals which are transmitted to the central unit from each subsystem are not the inputs and outputs but the residuals which are smaller. Because periodic communication sequence's introduction changes the observability of the system, a theorem is provided to discuss the observability of DNCS as well as to give a new system model under observable condition. On the basis of residuals transmitted from subsystems to the central unit, some steps are taken to get the inputs and outputs which are necessary for fault detection. Then, according to the new system model and obtained inputs and outputs, the central fault diagnosis unit based on the periodic system theory is designed under this communication pattern. Finally, a numerical example is provided to illustrate the effectiveness of the proposed method.