Hybrid Active-passive Fault-tolerant Control Research Of Nonlinear Networked Control System Under DETCS

For nonlinear networked control systems(NNCS)with possible actuator failures,the systems will be affected by external finite energy disturbances and the controller may have parameter perturbations.In this thesis,for the sake of improving the system's quality of control performance(QoP)and quality of communication service(QoS),hybrid active-passive fault-tolerant control strategy is designed to ensure system performance,and discrete event-triggering communication scheme(DETCS)is introduced to conserve network communication resources.The main research contents are as follows:1)Aimed at NNCS,a mathematical model based on T-S fuzzy model integrating event triggering condition,network-induced delay and actuator fault is established.Considering that the controller may have parameter perturbation and the system is affected by the external finite energy disturbance,a disturbed closed-loop fault model of NNCS is established.At the same time,a fault-tolerant control strategy which conforms to the characteristics of NNCS is designed based on the principle of parallel distributed compensation.2)Based on the model established in 1),a passive ?-stable fault-tolerant controller is designed to make the closed-loop system robust when known faults occur,while the offline-designed fault-detecting observer detects the faults that may occur in the system by using the continuous periodic sampling signals in real time.If unknown fault is estimated,on the one hand,the passive fault-tolerant controller is used to prevent the system from deteriorating.On the other hand,according to the fault information,the system can be compensated quickly to ensure the system's?-stability.3)Real industrial system is not only facing the problem that the actuator may fault and affect the stability of the system,but also will inevitably be stimulated by the external finite energy disturbance and the unfavorable factors such as the parameter perturbation of the controller elements.Therefore,a hybrid active-passive non-fragile fault-tolerant control strategy is proposed,which makes NNCS asymptotically stable when the actuator has known or unknown faults,and has a certain anti-interference ability to external finite energy disturbances.4)In order to further improve the quality of network communication service in the premise of ensuring the system control performance,the event generator is placed between the sampler and the fault detection observer(FDO),at the same time,considering non-uniform transmission of information,an augmented fault NNCSmodel is established instead of directly using periodic sampling signals to estimate faults.Firstly,passive fault-tolerant control strategy is designed offline,then fault detection and dynamic regulation mechanism is designed by integrating non-uniform signals from event generators,so that the system can save network resources and maintain fault-free performance as much as possible when actuator failures occur.5)Finally,all the above theoretical deductions are simulated and validated on the MATLAB simulation platform.The FDO designed in this thesis can estimate faults effectively.Comparing the response curves of the same model under passive fault-tolerant control(PFTC),active fault-tolerant control(AFTC)and hybrid activepassive fault-tolerant control,it is found that the hybrid fault-tolerant control scheme can effectively combine the advantages of PFTC and AFTC,and make the system have fault-tolerant ability for both in-set and out-set faults.Of course,the introduction of DETCS greatly saves network communication resources and improves the efficiency of resource utilization.