Distributed Fault Diagnosis for Networked, Embedded Automotive Systems

Networked embedded systems, such as modern automobiles, consist of a large number of physically distributed nodes (subsystems). Each node communicates with other nodes via a network. With the rapid growth in the number of control units, a global diagnosis method, which collects the diagnostic information from all the subsystem controllers, is not practical because of high communication requirements and time delays induced by centralized diagnosis. This paper presents a distributed diagnosis algorithm based on a digraph model and a local fault-test dependency matrix (D-matrix) at each node. Each local diagnoser first performs local diagnosis, taking into account local sensed information only. Then, the local diagnoses are transparently updated to a global diagnosis through communication among nodes, constrained by the topology of interconnected digraph models. The distributed diagnosis algorithm is evaluated on several real-world examples.