Online fault detection and isolation of nonlinear systems based on neurofuzzy networks

H. T. Mok, C. W. Chan

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


An online fault detection and isolation (FDI) technique for nonlinear systems based on neurofuzzy networks (NFN) is proposed in this paper. Two NFNs are used. The first one trained by data obtained under normal operating condition models the system and the second one trained online models the residuals. Fuzzy rules that are activated under fault free and faulty conditions are extracted from the second NFN and stored in the symptom vectors using a binary code. A fault database is then formed from these symptom vectors. When applying the proposed FDI technique, the NFN that models the residuals is updated recursively online, from which the symptom vector is obtained. By comparing this symptom vector with those in the fault database, faults are isolated. Further, the fuzzy rules obtained from the symptom vector can also provide linguistic information to experienced operators for identifying the faults. The implementation and performance of the proposed FDI technique is illustrated by simulation examples involving a two-tank water level control system under faulty conditions.

Original languageEnglish
Pages (from-to)171-181
Number of pages11
JournalEngineering Applications of Artificial Intelligence
Issue number2
Publication statusPublished - Mar 2008


  • Fault detection and isolation
  • Fuzzy logic
  • Neural networks
  • Neurofuzzy networks
  • Nonlinear systems


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