“…This constraint, however, is too strict to be satisfied in practical applications. In order to loosen the observer matching condition, algebraically decomposed technique, 8 unscented transformation (UT), 9 population-based approaches, 10 optimization methods 11,12 and neural networks, 13 have been incorporated into the framework of UIO, which greatly improves the performance of the original method in applications. Stochastic filters 11,14,15 such as Kalman filter and particle filter, have been introduced to solve the fault detection and isolation problems in recent years.…”