Research For Prescribed Performance Fault-tolerant Control Of Uncertain Nonlinear Systems

With the continuous application and innovation of contemporary industrial technology,the control theory has been rapidly developed and expanded.When the system can satisfy more demands at the same time,this leads to a significant increase in complexity,an increase in control difficulty,and a natural increase in the probability of system failure.Fault-tolerant control is the ability to diagnose,identify,and compensate for system faults in real time through the controller.It is similar to the immune system of the human body,which can greatly reduce the workload of engineering and technical personnel,and effectively improve the fault detection and automation level of industrial systems.In addition,for some systems that require preset transient and steady-state performance,such as a given stable synchronization error,maximum error overshoot and error convergence rate,prescribed performance control also plays a key role in ensuring the realization of control objectives.In this paper,an adaptive method is used to design a prescribed performance fault-tolerant controller for nonlinear systems with external disturbances and actuator faults.The main research results and contributions are described as follows:Consider a low-complexity prescribed performance fault-tolerant control problem for a class of MIMO uncertain nonlinear systems with actuator faults,coupled states,and unknown control directions.Firstly,proper logarithm-type error conversion functions and smooth orientation functions are linked to design the continuous control signals in the state feedback controller.Then,based on the idea of proof by contradiction,it is shown that the state errors converge to a predictable compact set at a corresponding rate.Meanwhile,the boundedness of any closed-loop signals might be guaranteed.The numerical and actual simulation examples are delivered to demonstrate the effectiveness of the proposed control strategy at last.A low-complexity global fixed-time prescribed performance fault-tolerant control of uncertain nonlinear pure-feedback systems with actuator faults and external disturbances is realized.First of all,a new fixed-time function in view of inverse trigonometric function is proposed and used to define the state errors.Then,proper root-type error conversion functions and smooth orientation functions are linked to design the continuous control signals in the state feedback controller.In addition,based on the idea of proof by contradiction,it is shown that the state errors converge to a predictable compact aggregate at the definite rate at a fixed time.Meanwhile,the boundedness of any closed-loop signals might be guaranteed.The simulation results and algorithm comparisons are delivered to demonstrate the effectiveness and superiority of the proposed control strategy at last.