Research On Fault Estimation And Adaptive Fault-Tolerant Control For A Class Of Linear Systems

Due to the characteristics of large scale and high complexity of modern control system,we put forward higher requirements for the security and reliability of systems,and fault-tolerant control can provide strong guarantee for the security and reliability.Therefore,fault-tolerant control has become a research hotspot.At the same time,as the basis of fault-tolerant control,fault diagnosis technology has also been attached great importance.In the field of fault diagnosis,fault detection,isolation and fault estimation have become research hotspots.In particular,fault estimation which has the function of detection and isolation,has become a hot research topic in recent years.This is an important reason for the study of fault estimation and fault-tolerant control.The problems of process fault estimation and output feedback based adaptive fault-delay tolerant control for two different linear control systems have been studied in this paper.The main work can be summarized as follows:1.For a class of linear control systems with process faults and disturbances,a suitable linear transformation matrix is introduced to isolate the disturbance in the measured output.Then,the plant is converted into a desired system under a reasonable variable substitution.For the desired system,a fault estimator is designed and optimized by fully using the output,its derivatives and integrals.Based on the designed estimator,the initial fault estimates with a good accuracy can be obtained.With the initial fault estimates and k step fault estimation technique,the fault estimation and its convergence for process faults has been solved.The effect of disturbances on estimation error differential equations can be constrained effectively via the introduction of the variable substitution.The H_?stability result for the obtained estimation error systems is given in the form of linear matrix inequality(LMI).Finally,a simulation example is given to compare the k-step fault estimation method with the mean fault estimation method.The simulation results show that the k-step fault estimation method converges to the fault truth value faster than the mean fault estimation method.2.Fault and delay accommodating simultaneously for a class of linear systems subject to state delays,actuator faults and disturbances is investigated in this work.A matrix norm minimization technique is applied to minimize the norms of coefficient matrix on time delay terms of the system in consideration.Compared with the matrix inequality scaling technique,the minimization technique can relax substantially the obtained stability conditions for state delay systems,especially,when the coefficient matrices of time delay terms have large order of magnitudes.An output feedback adaptive fault-delay tolerant controller(AFDTC)is designed subsequently to stabilize the p,lant with state delays and actuator faults.Compared with the conventional fault tolerant controller(FTC),the designed output feedback AFDTC can be updated on-line to compensate the effect of both faults and delays on systems.Finally,the proposed AFDTC is applied to the second-order chemical reactor model and time-delay linear systems with large order of magnitudes of time-delay coefficient matrix,respectively,to show its feasibility and effectiveness.