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.