Research On Event-triggered Asynchronous Fault-tolerant Control For Stochastic Systems

When studying the control problem of Markov jump stochastic systems,there exist problems including time delays,actuator faults and external disturbances,which will make the modes information(e.g.the system modes)loss.In this kind of system,incomplete information transmission may bring about the asynchronous phenomenon existing between the original system and the controller even the actuator.In this paper,the asynchronous problem between the systems and the controller/actuator is described by the hidden Markov model.At the same time,in the actual control system,because the network is taken into consideration as well as the information interaction and transmission between the system components(such as sensor,controller,actuator)are often achieved through the network,so they will inevitably cause network problems such as channel congestion,network induced time delay and packet loss,which result in network resources cannot be fully utilized.For the sake of increasing the utilization of network resources and avoiding Zeno behavior,a mode-dependent discrete-time event-triggered mechanism is proposed in this paper.In addition,due to the aging of equipment or some unpredictable external environment,one or multiple types of actuator faults(for instance partial fault,outage fault,bias fault and stuck fault)may occur,which will degrade the system performance and even crash the system.The fault-tolerance control method can effectively cope with the impact of failure on the system while maintaining system stability.Therefore,for Markov jump stochastic systems,the proposed design methods of asynchronous fault-tolerant controller based on hidden Markov model and mode-dependent event-triggered mechanism have indispensable significance about theoretical research and practical application value.This paper analyzes the stability and reliability of the Markov jump stochastic system by using hidden Markov model,adaptive control and linear matrix inequality.Our main innovative research contents are as follows:(1)The problem of asynchronous H_?fault-tolerant control for discrete-time Markov jump systems is studied in this paper.First,the asynchronous problems among the system modes,the controller modes and the actuator modes are represented by two corresponding hidden Markov models.Based on this,the mode-dependent controller and the mode-dependent actuator are designed respectively.In order to further improve the utilization efficiency of network resources,a mode-dependent discrete-time event-triggered mechanism is designed.Finally,by establishing the mode-dependent Lyapunov-Krasovskii functional,the sufficient conditions are presented to ensure that the closed-loop system is stochastically mean square stable with a prescribed H_?performance index.(2)The event-triggered asynchronous adaptive fault-tolerant control problem of continuous-time Markov jump systems subject to multiple-types actuator faults including partial fault and stuck fault is investigated.Firstly,an adaptive event-triggered mechanism is proposed,which greatly enhance the utilization of network resources.Furthermore,by coupling the unknown actuator stuck faults and the unknown external disturbances into the proposed augmented disturbances,the upper and lower bounds of them can be estimated online at the same time.Finally,the proposed adaptive event-triggered asynchronous fault-tolerant controller based on the triggered state and estimated values can mitigate the impacts of stuck faults,partial faults and external disturbances on the system while ensuring the closed-loop system is uniformly ultimate boundedness.(3)The adaptive fault-tolerant control method of the networked stochastic unmanned surface vehicles with Markov jump attribute is researched.Firstly,for this system,the estimation problem of multiple-types actuator faults including the partial faults and bias faults as well as unknown bounded external disturbances is studied.In order to adapt to the changes of the unmanned surface vehicles with random switching characteristic,an asynchronous fault-tolerant controller is designed through an adaptive event-triggered sampling control approach is employed.Subsequently,by introducing the mode-dependent Lyapunov-Krasovskii functional,an asynchronous adaptive fault-tolerant control method is proposed to ensure the stability of the closed-loop system on the basis of effectively compensating multiple-types of faults and external disturbances and the effectiveness of the proposed method is verified by numerical simulation.