Research On Prescribed Performance Fault-tolerant Control Of A Class Of Disturbed Nonlinear Systems With Actuator Faults

Considering the actual working environment of system equipment is usually complex and changeable,and the actuator tends to be out of order during long-term operation.The fault-tolerant control methods can be introduced into the systems properly,and they can provide strong guarantees for the reliable operation of the systems.However,the actual system equipment is characterized by multivariate,nonlinear and uncertain,which bring more challenges to the fault-tolerant control.Therefore,this paper conducts fault tolerance control with prescribed performance for a class of disturbed nonlinear systems with actuator faults.The main research contents are as follows:Aiming at the output constraint control problem of a class of nonlinear systems with actuator fault and external disturbance,a fast terminal sliding mode fault tolerant control method based on fixed time disturbance observer is proposed: the actuator fault and external disturbance of the system are regarded as the fault disturbance term,and external disturbance and the fault disturbance term are estimated by designing a fixed time disturbance observer;a distributed fast terminal sliding mode fault-tolerant controller is designed based on the backstepping control method,which can track the given value accurately even when the actuator fault occurs.The nonlinear first order filter is introduced to solve the "explosion of complexity" problem in controller derivation.The simulation result shows that the tracking error of the system can satisfy the prescribed transient and steady-state performance.Aiming at the finite-time control problem of a class of disturbed nonlinear systems with actuator faults under full state constraints,a fault-tolerant control method with finite-time prescribed performance is proposed based on the super-twisting disturbance observer: super-twisting disturbance observers are designed to observe external disturbance and the lumped disturbance term composed of the actuator bias fault and external disturbance in finite time;the finite-time prescribed performance fault-tolerant controller under full state constraints is designed by combining the backstepping method,the modified barrier Lyapunov function method and the improved prescribed performance function method;the "explosion of complexity" problem in the controller design is solved by the command filters with error compensation.The effectiveness and feasibility of the proposed method are verified by simulation and experiment.Aiming at the predefined-time control problem of a class of disturbed nonlinear systems with actuator fault under full state constraints,a prescribed performance fault-tolerant control method under full state constraints is proposed based on predefined-time observers: external disturbance and the fault disturbance term are estimated by designing predefined-time observers;based on the conventional finite-time prescribed performance function,the innovative prescribed performance function has a better constraint effect on the system output;the prescribed performance fault-tolerant controller under the full state constraints is designed by combining the backstepping method,the asymmetric barrier Lyapunov function method with the innovative prescribed performance function.The novel command filters with error compensations is designed to solve the "explosion of complexity" problem in controller derivation.The simulation and experimental result shows that all states of the system meet the prescribed constraints,and it has better fault tolerance control performance.