Research On Fault Estimation And Active Fault-Tolerant Control Of Network Systems

Networked control systems are information physical systems formed by the interaction and fusion of operation modules and actual objects in the network space.Their actual physical systems,network communication systems and corresponding generalized functional security problems are deeply related.The internal information resources of the system are shared to facilitate remote operation and control.The overall structure of modularization and integration effectively reduces the design and operation costs,Networked control systems are widely used in aerospace,intelligent manufacturing,remote control and other frontier fields because of its many advantages.Traditional fault diagnosis and fault-tolerant control methods are difficult to be directly applied to networked control systems.Therefore,in order to overcome the issues that control systems in non-ideal network environments can still maintain stable operation and achieve suitable performance indexes under the influence of factors such as faults and external disturbances.Under this background,this project addresses the problems related to fault estimation and active fault-tolerant control of networked control systems,and the main work and research achievements include the following aspects:Firstly,the problem of joint state and fault estimation and active fault-tolerant control of a class of discrete-time networked control systems with actuator faults and partial decoupling perturbations is investigated.Under the consideration of random loss of measurement data,an unknown input observer(UIO)is constructed to jointly estimate the system state and faults by using an augmented system approach.Then,based on the online estimation of states and fault,an active fault-tolerant control law is developed by using signal compensation strategy.Intensive stability analysis is carried out to obtain the sufficient condition for the existence of the desired observer and the controller.Ultimately,the designed estimator and fault-tolerant controller can compensate for the impact of faults on the system while still ensuring the input-state stability performance of the original system.Secondly,a fault estimation and integrated fault-tolerant control control strategy based on state feedback is proposed for a stochastic discrete-time networked control system subject to random network attacks.While considering the phenomenon of random deception attacks,a commonly considered stochastic Brownian parameter perturbation is introduced.Here,it is assumed that the disturbance signal can be associated with system state,control input,uncertainty and unexpected faults.By combining the incremental system approach,the unknown input observer,the optimization algorithm,and the observer-based control as well as the signal compensation,both the simultaneous estimation of states and faults can be achieved and the influence of fault signals and random disturbance factors can be reduced,and finally it is proved that this integrated design strategy can guarantee the mean square exponential boundedness and robustness of the whole dynamic system.Finally,an integrated design scheme for fault estimation and active fault-tolerant control is studied for a class of networked control systems with multiple faults and stochastic parameter perturbations based on event-triggered mechanisms.A set of Bernoulli distributed white sequences is used to describe the stochastic parameter perturbations under norm bounded conditions,the event-triggered mechanism is introduced at the output of sensor fault and the corresponding fault observer is investigated by the obtained non-uniform sampling information to achieve the joint estimation of the system state and sensor fault.A fault-tolerant controller based on dynamic output feedback signal compensation is constructed,and then the gain matrix of fault observer and fault-tolerant controller is obtained by using the augmented system method and linear matrix inequalities to achieve integrated fault estimation and fault-tolerant control under multi-performance constraints.