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Active Fault Detection And Fault Tolerant Control Of Stochastic Networked Control Systems

Posted on:2020-06-13Degree:MasterType:Thesis
Country:ChinaCandidate:P JiangFull Text:PDF
GTID:2428330575457728Subject:Control Science and Engineering
Abstract/Summary:PDF Full Text Request
Due to the continuous development of computer technology,the control system has gradually evolved from a closed centralized system to an open,distributed system.At the same time,the development of communication network technology has promoted the organic combination of data communication networks and traditional closed-loop control systems,making networked control systems a hot research topic..Due to the intervention of the network,data transmission problems are inevitable in the networked control system,such as packet loss,time delay,multi-packet transmission,and network scheduling methods.In addition,in the actual networked control system,the occurrence of actuator fault and sensor fault is inevitable,resulting in the reduced reliability of the networked control system.The existence of these problems makes the control problem of the networked control system more difficult.In this thesis,fault diagnosis and fault-tolerant control of the networked control system is studied.The specific contents of this thesis are shown as follows:(1)For the scalar parameter fault system with random delay,the Laplace transform is used for system transformation,and then the active fault detection is performed on the equivalent system based on the set-membership estimation theory.Using active fault detection methods,the design of the auxiliary signals can greatly affect the performance of fault detection.It is assumed that the disturbance or noise in the system obeys a certain distribution and is bounded.For the auxiliary signal design,the worst case of uncertainty to avoid false detection is considered.In order to optimize the optimal auxiliary signal,the concept of cost function is introduced in this thesis,combined with the theory of optimal control and parameter estimation.Then the optimal auxiliary signal can ensure that the active fault detector can effectively motivate potential faults,quickly and accurately distinguish the fault model from the normal model,and minimize the impact of auxiliary signals on system performance.The algorithm is also verified by simulation,and it is proved that the algorithm is effective.(2)For networked control systems with random delay,a fault diagnosis algorithm and sliding mode fault-tolerant control algorithm for networked control systems with random delay based on Laplace transform are proposed.In the system,two kinds of random delays are considered,which obey exponential distribution and uniform distribution respectively.The original system is transformed into an equivalent system with no apparent delay by Laplace transform.The stability of the observation error system is analyzed by the Lyapunov stability theorem.The observer gain matrix can be obtained by solving the corresponding LMI.Then,based on the fault diagnosis information,the sliding mode fault-tolerant controller is designed.Finally,the computer simulation results further verify the effectiveness of the fault diagnosis algorithm and the fault-tolerant control algorithm.(3)For a networked control system with packet loss problem,the packet loss process is described as a Bernoulli process,with 0 or 1 indicating the transmission status of the sensor signal and control command.If the variable is 1,the transmission is normal.If the variable is 0,the data is lost.In this thesis,the random packet loss process in the networked control system is described by Bernoulli distribution.In the fault diagnosis section,fault diagnosis is performed by designing a residual signal and an adaptive mediation rule for the faulty system,and then based on the fault diagnosis information,model predictive control is used for fault tolerant design for the system.By optimizing the solution model predictive control system,a suitable fault-tolerant controller is designed to complete the active fault-tolerant control of the system.Then the closed-loop stability of the system is analyzed.At the end of the thesis,the feasibility of using MATLAB simulation is tested.
Keywords/Search Tags:Networked control system, Scalar parameter system, Laplace transform, Packet loss, Time delay, Fault diagnosis, Model predictive control
PDF Full Text Request
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