Research Of Active Disturbance Tolerant Control For Uncertain Systems Considering The Incipient Faults

Incipient fault diagnosis as one of the key fault diagnoses to ensure the normal operation of mechanical equipment,the software or hardware equipment system with incipient fault has been obtained the domestic and foreign scholar's attention and takes seriously.Such as the early pitting,peeling,cracking in rolling bearings.However,because of the incipient has the characteristics of small amplitude in early time,happens gradually,not easy to find.Moreover,in actual working conditions,the change information of incipient fault easily conceals by the disturbance or noise.So,building suitable disturbance rejection model can estimating minor faults effectively,early warning of failure systems and prevent the occurrence of large-scale fault,so that ensure smooth running of the system.Therefore,research on small fault diagnosis method under the influence of disturbance has been paid more and more attention and discussion from industry and academia and in every field.In order to explore the advantages and disadvantages of active disturbance rejection control in incipient fault diagnosis.This paper investigates the system with incipient fault and disturbance.Beginning at the linear system with system error and disturbance to estimate the incipient fault.And based on it,introduce the active disturbance rejection control theory and fault tolerant control theory to explore its feasibility and excellent characteristic in incipient fault diagnosis.The major work and innovation of this paper are shown as follows:(1)Aiming at the fault system with system error,measuring error and disturbance,the incipient fault diagnosis method based on adaptive observer is proposed.On the one hand,the analysis model of system error has been proposed.Separate the system error into two part,one of the parts is random error and the other one caused by the system error at the previous time.On the other hand,based on the above analysis of system errors,insert the disturbance in the linear time-invariant system with the actuator incipient fault,integrate the advantages and disadvantages of the system,the adaptive incipient fault diagnosis observer has been designed.The simulation results show the incipient fault diagnosis observer can track the dynamics of incipient faults effectively.(2)Aiming at it is difficult to find the incipient fault and it easily masked by disturbances.First,according to the incipient model described in existing literature,an incipient fault diagnosis method based on ESO has been proposed.This method can effectively separate incipient fault as a new state variable from the disturbance.Then,by using coordinate transformations,the original system is decoupled into two subsystems.Specially,an adaptive observer of fault system is designed for the one subsystem with the incipient fault but not relevant to the disturbance,and an ESO based on ADRC is designed for another one which not only have the disturbance but also exist the incipient fault.In the simulation part,the effectives of this method has been proved.(3)Aiming at the diagnosis method in the system with soft incipient fault and abrupt incipient,a method based on active disturbance rejection control combine with fault tolerant control has been put up to detecting the dynamics changes of incipient fault.First,analysis models of soft incipient fault and abrupt incipient according to the definition of incipient fault.Then,consider the incipient as a new state to estimation and depart it from system disturbance.By the section of simulation,a detail analysis the disadvantage and advantage of the active disturbance rejection control combine with fault tolerant control method to incipient fault diagnosis.