Event-triggered Fault Diagnosis And Fault Tolerant Control

To ensure the safety of complex engineering systems,fault diagnosis and fault-tolerant control technology have been widespread concerned in the past half century.On the other hand,with the popularity of network and embedded technologies in complex engineering systems,network and computational resource constraints make conventional periodic sampling no longer applicable.And actively adjusting the sampling period such as event-triggered sampling and other nonuniform sampling modes have been put forward and become new research hotspots.However,this non-uniform sampling pattern increases the difficulty of fault diagnosis and fault-tolerant control due to its time-variances and uncertainties.In this paper,we focus on the dynamic system of non-uniform sampling mode,such as event triggering,and develop a series of research on fault diagnosis and fault-tolerant control.The main work is as follows:We devote to design a discrete time fault estimation observer,for nonuniformly sampled systems from an uncertain system point of view.First,the nonuniformly sampled system is modeled as an equivalent polytopic system with norm-bounded uncertainties,according to polytopic theory.A discrete-time time-varying fault estimation observer with multiple design freedom is then constructed,and a sufficient condition given in linear matrix inequality(LMI)is provided to obtain the constant filter gain and ensure not only the asymptotic stability of fault estimation error but also the robustness of uncertainties.Compared with the existing observer designed based on continuous-time delay approach,the proposed one has better estimation accuracy and larger sampling interval and is easy for digital implementation.Considering the sampling period is passive uncertain in chapter 2,an event-triggered sampling and active fault-tolerant control co-design scheme based on fault diagnosis observer is developed.We first design a fault diagnosis observer to simultaneously estimate both the fault and the system state using the event-triggered sampled outputs.Some H? constraints between the estimation errors and the output transmission error are also established.Then,based on the estimates,the state-based static and dynamic fault-tolerant controllers are constructed to co-design the event-triggered mechanism and fault-tolerant controller with the help of the H?constraints established above.The proposed scheme can not only guarantee the stability of the faulty system but also reduce the sensor transmission cost.In order to overcome the event-triggered sampling need to monitor the system state continuously,we consider the fault-tolerant problem of non-uniformly sampled system based on Quasi-Kalman filter with actuator faults and bounded disturbances.By means of uncertain polytopic theory,we first design a discrete-time Quasi-Kalman observer,to simultaneously estimate the fault and state using the self-triggered nonuniform sampled outputs.Then,based on the state estimates,the self-triggered sampling technique is further designed to determine the sampling time.We prove that the faulty system is input-to-state stable(ISS)under the proposed fault-tolerant controller and self-triggered sampling mechanism.The effectiveness and superiority of the above method are verified by a series of benchmark cases and numerical simulations.