Application of fault propagation intensity in fault diagnosis of CNC machine tool

ABSTRACT To realize dynamic and real-time multi-fault decoupling and diagnostic CNC machine tools, this study proposes a dynamic fault diagnosis method that is based on fault propagation intensity. Integrated fault mechanism analysis, directed graph theory, and interpretative structure model are used to construct a fault propagation hierarchical model to visually depict complex fault causality. The influence degree of component nodes and the fault influence degree of edges are calculated using PageRank and a coupling degree function. The fault propagation probability of component nodes is determined by synthesizing node fault probability. Fault propagation intensity is defined by the probability of fault propagation and edge-betweenness to characterize the behavior of fault propagation dynamically. Combined with the hierarchical fault propagation model, the critical path and node are determined. A certain type of CNC machine tool is taken as an example to carry out a specific application. Results show that the hierarchical model of system fault propagation realizes multi-fault decoupling and clarifies the process of fault propagation. The critical path is identified according to the fault propagation intensity, the deviation caused by describing the behavior of fault propagation based on a single index is avoided, and the accuracy of fault diagnosis is improved.