Research On Fault Detection And Fixed-time Fault Tolerant Control Of Molding Process System

Molding process system is an important part of manufacturing industry,which has a wide range of applications in material forming and industrial production.However,there are series of problems in the molding process system,such as nonlinearity,input delay and actuator fault,which seriously affect the stability and efficient of operating process.In addition,on the basis of achieving stable control,molding process system also puts forward higher requirements for operation performance.Therefore,this paper utilizes unknown input observer to detect actuator faults in molding process system;Aiming at the fault-tolerant control issue of the system,a fixed-time fuzzy adaptive fault-tolerant control method is designed based on command filtering and prescribed performance technique;Pade approximation is adopted to solve the problem of input delay.Finally,the control method is applied to the molding process system model,which proves the feasibility and superiority of the controller designed to solve the above problems.The main research work of this paper is as follows:(1)Aiming at the problem of actuator fault and unknown disturbance in molding process system,this paper adopts the fault detection technology based on unknown input observer.The external disturbances and noises of the system are regarded as unknown inputs.The unknown input observer is introduced to generate the fault residual signal which is highly sensitive to the actuator fault signal but not sensitive to the unknown input,so as to improve the robustness of the fault detection of the molding process system.(2)Aiming at the problem of nonlinearity,actuator fault and input delay in molding process system,a fuzzy adaptive fault tolerant controller combined with fixed-time command filtering is proposed.Based on the fixed-time command filter fault-tolerant control law,the impact of actuator fault can be quickly compensated;The fuzzy adaptive law is designed to solve the nonlinear problem of the system;According to Pade approximation,the problem of unknown input delay is solved;The fixed-time convergence property of controlled system is proved to ensure that the tracking error converges into a small neighborhood of the system origin in fixed time,and the convergence time not related to the initial states of system.(3)Furthermore,a fixed-time fault-tolerant control method combined with prescribed performance is designed to meet the strict requirements of control performance during the operation of molding process system.The introduction of prescribed performance function successfully limits the tracking error within the prescribed range,thus restricting the steady-state error,maximum overshoot and convergence rate,and further optimizing the system performance;Combined with the fixed-time technique,the fast and accurate compensation of actuator fault is realized to ensure that the system signal converges to the stable region within fixed time.Finally,the algorithm is applied to the molding process system model,and the superiority of the proposed prescribed performance control method is proved by adopting comparative simulation experiments.