PhD Thesis

Diagnosis and Fault-tolerant Control of Dynamic System using Set-based Approaches

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  • Started: 17/04/2015
  • Thesis project read: 06/06/2016


In order to produce ecient and high-quality products, modern process systems must satisfy their function correctly. Consequently, there are some important issues as safety operation, cost efficiency or environmental protection that have to be considered in engineering applications. In this context, faults can be the cause for unsatisfactory performance or even instability of the system. There are several possible explanations for occurrence of the faults, e.g., design errors, implementation errors, human operator errors, etc. Therefore, Fault Detection and Isolation (FDI) has been a very active research topic for the scientific community since 1970's. Generally speaking, the goal of FDI theory is referred to nd the root causes of the fault occurrence. After detecting the fault, maintaining the overall system stability and having an acceptable performance will
be the next target to be achieved. Therefore, Fault-tolerant Control (FTC) is the name used to describe all techniques capable of maintaining desirable performance of the system. Since 1980's, there has been an increasing interest in FTC for improving the safety and reliability of the system from academic and industrial communities.

Generally, FTC techniques, rstly are concerned about diagnosis (detecting and identifying) the fault, and then designing the suitable controller for the system. Generally, the right state estimation is required for fault detection (FD) and FTC techniques, since both of them are based on knowing the state of the system. Moreover, the estimation approaches can be divided into stochastic and deterministic approaches. Stochastic approaches assume these uncertainties are described by known statistical distributions, but in the deterministic approaches, the uncertainties are assumed to be unknown but bounded.

The motivation of this thesis is to design the new method for fault diagnosis of complex systems (non-linear and/or distributed parameter systems) for increasing their performance since even a small fault can have an important influence on the performance of the system. Set-theoretical approaches, which are quite well established tools in control for proving system stability, will be used for considering the uncertainty in fault diagnosis. To evaluate the fault diagnosis performance, the minimum detectable fault can be obtained for the system when malfunctions occur. The aim is to design the new set-based FD and FTC approaches by integrating all available ones that can be used into the non-linear systems.