Research On Adaptive Fault-Tolerant Control For A Class Of Nonlinear Multi-Agent Systems

With the rapid development of network communication technologies,the control theory and the artificial intelligence,the distributed control problems of the multi-agent systems have attracted extensive attention of experts and scholars,and have become one of the important research topics in the field of control.Due to the fact that the multi-agent systems contains a group of agents,the system will inevitably fail in the process of operation.In addition,due to the information interaction between agents,the fault in some subsystems may affect some or all subsystems as well as the achievement of coordination goals of multi-agent systems,even leading to unexpected catastrophic acci-dents.Therefore,it is very important to improve the security and reliability of multi-agent systems.The emergence and development of the distributed fault-tolerant control tech-nology provide an effective way to solve the problem.The actual systems in nature are almost nonlinear systems,and the complex multi-agent systems contain more nonlinear characteristies.Due to the complexity of the nonlinear system,the control theory of the nonlinear multi-agent systems is not perfect as the linear multi-agent systems.The re-search on distributed fault-tolerant control for nonlinear multi-agent systems is still in its infancy,and there are still many problems to be further studied.On the basis of the previous work,this dissertation is concerned on the distributed fault tolerance control for multi-agent systems with matched unknown nonlinear function by using network topology,fuzzy logic,backstepping technique and adaptive technology.First,a distributed adaptive fault-tolerant consensus controller and a distributed adaptive fault-tolerant containment controller are designed for a class of nonlinear multi-agent sys-tems with actuator faults.Then,by using adaptive technique a distributed fault-tolerant controller is designed for nonlinear multi-agent systems under switched network topolo-gy.Furthermore,an output feedback fault-tolerant controller based on state observer and fault estimator is designed for a class of nonlinear multi-agent systems under undirected connected topology.Moreover,an adaptive output feedback fault-tolerant control scheme based on backstepping technique is proposed for strict-feedback multi-agent systems un-der directed topology.Finally,an output feedback fault-tolerant controller based on state observer and fault estimator is designed for nonlinear multi-agent systems under directed topology.Some theoretical results are applied to the reduced-order aircraft model,the ship yaw dynamics model and the B747-100/200 aircraft model.Simulation results show the effectiveness of the proposed methods.The main work of this paper are given as follows:1.The nonlinear multi-agent systems with external disturbances and actuator faults are considered.The fuzzy logic is used to identify the unknown nonlinear function and the adaptive technique is introduced to estimate the norm of the weighting coefficients in the fuzzy logic system.Then,a distributed adaptive fault-tolerant consensus controller and a distributed adaptive fault-tolerant containment controller are designed,respectively.Compared with the existing distributed control methods for nonlinear multi-agent sys-tems,the designed controllers cannot only reduce the number of adaptive parameters bust also be used to compensate the actuator stuck and outage faults.Finally,the reduced-order aircraft models are used in simulation examples to show the effectiveness of the proposed method.2.The problem of the distributed fault-tolerant control for nonlinear multi-agent systems under switching network topology is investigated.First,the fuzzy logic is used to identify the unknown nonlinear function.Then,the adaptive update laws with switching mechanism are designed.Furthermore,a distributed adaptive fault-tolerant controller with the switching mechanisms is designed to compensate actuator faults.In addition,by using the Lyapunov stability theory,it is proved that the proposed distributed fault-tolerant controller can compensate the actuator faults effectively and the consensus error is uniformly ultimately bounded.Finally,the B747-100/200 aircraft model is used in simulation example to show the effectiveness of the proposed method.3.The problem of the output feedback distributed fault-tolerant control for nonlinear multi-agent systems is investigated.The fuzzy logic is used to identify the unknown nonlinear function.The state observer and the fault estimator are designed to estimate the states and faults of the system,respectively.Then,a distributed adaptive fault-tolerant controller is designed.In addition,by using the Lyapunov stability theory,it is proved that the proposed output feedback fault-tolerant controller can compensate the actuator faults effectively.Finally,the ship yaw dynamics model is used in simulation example to show the effectiveness of the proposed method.4.The problem of the output feedback fault-tolerant control for strict-feedback multi-agent systems under directed graph is investigated.This chapter studies the actuator outage and stuck faults under the assumption that the topological graph contains a direct-ed spanning tree.The local K-filter is designed to estimate the system state.Then,the low pass filter is introduced and the backstepping method is used to design the controller.In addition,by using the Lyapunov stability theory,it is proved that the proposed output feedback distributed fault-tolerant controller can compensate actuator faults effectively.Finally,the ball-beam model is used in simulation example to show the effectiveness of the proposed method.5.The problem of the output feedback distributed fault-tolerant control for nonlinear multi-agent systems under directed graph is investigated.The fuzzy logic is used to iden-tify the unknown nonlinear function.Then,a distributed adaptive fault-tolerant controller based on the state observer and the fault estimator is designed.In addition,by construct-ing integral type Lyapunov function and using Lyapunov stability theory,it is proved that the proposed output feedback distributed fault-tolerant controller can compensate actuator faults effectively.Finally,the B747-100/200 aircraft model is used in simulation example to show the effectiveness of the proposed method.Finally,the results of the dissertation are summarized and further research topics are pointed out.