Fuzzy model-based observers for fault detection in CSTR

•Four fuzzy model-based observers were designed for fault detection in a CSTR.•Diverse faults and a noise signal were induced in the CSTR system.•All the fuzzy observers were able to detect the faults.•The Walcott-Zak fuzzy observer had the best performance when no fault was induced.•The Utkin fuzzy observer had the best performance when the faults were induced.

Under the vast variety of fuzzy model-based observers reported in the literature, what would be the properone to be used for fault detection in a class of chemical reactor? In this study four fuzzy model-based observers for sensor fault detection of a Continuous Stirred Tank Reactor were designed and compared. The designs include (i) a Luenberger fuzzy observer, (ii) a Luenberger fuzzy observer with sliding modes, (iii) a Walcott-Zak fuzzy observer, and (iv) an Utkin fuzzy observer. A negative, an oscillating fault signal, and a bounded random noise signal with a maximum value of ±0.4 were used to evaluate and compare the performance of the fuzzy observers. The Utkin fuzzy observer showed the best performance under the tested conditions.