| With the innovation and development of science and technology,control systems are more and more widely used in modern practical production and life,and people pay more and more attention to their safety and reliability.The complicated control system will not only be affected by external interference,but also the internal components are prone to failure.When the actuator,sensor or component of the system itself fails,it will have a significant impact in actual production,even endanger the safety of life and property.Adaptive fault-tolerant control method can ensure that the system can still run stably and have ideal performance when a fault occurs.It is worth noting that stability is the key condition to ensure the normal operation of the system.Most of the existing results can guarantee the system stability within finite time,such as Lyapunov stability.However,this stability cannot achieve the desired performance in a finite time,and there are some defects.And for the practical engineering system,it is required to achieve the general stability of the system while ensuring the transient performance in a finite time.Finite-time stability can ensure that the system can achieve the ideal control objectives in a finite time,which is widely used in aircraft control and other fields.Based on this,this thesis will make further research on fuzzy adaptive finite time fault-tolerant control of nonlinear systems.The finite time adaptive filter control problem is studied for strict-feedback nonlinear systems with actuator faults and state constraints.First,with the aid of the backstepping technique,the controller and the adaptive laws are designed to compensate the actuator faults and parameter uncertainties.Then,the dynamic surface control is used to establish a first-order filter to alleviate computational burden for the reason of the derivative of virtual control laws.In addition,none of the system states violate predefined constraint boundaries by utilizing a 7)2)-type barrier Lyapunov function.Furthermore,the boundedness can be ensured for all the closed-loop signals and better tracking performance of the system is obtained within a finite-time.Finally,the simulation examples are shown to prove the feasibility and effectiveness of the proposed strategy.For strict feedback nonlinear systems with unknown disturbances and input delays,the problem of finite time actuator saturation control is studied by combining fuzzy logic system technology.First,under the framework of adaptive backstepping recursion,the virtual control input and the corresponding adaptive law are constructed,and the problem of input saturation is compensated when the actual control input is designed in the last step.Then,fuzzy logic system is used to approximate the unknown nonlinear term of the system,and Pade approximation technique is considered to deal with the time delay problem caused by network system.Finally,the simulation results show that the proposed control mechanism can ensure that the signals in the closed loop system are bounded and the system state tends to be stable in a finite time,which shows the effectiveness of the method. |
