Research On Distributed Fault-tolerant Tracking Control Technology For Multi-agent Systems Based On Sliding Mode Method

With the development of the society,engineering and communication,in recent years,the multiagent systems(MASs)have attracted numerous researchers' attention.That is largely due to the advantages of multi-agent systems when replace the traditional high-dimensional complex single systems.In addition,owing to the complex structure and high requirement of security for multi-agent systems,the research on fault-tolerant control of multi-agent systems is of great practical significance.In this paper,the distributed fault-tolerant tracking control technology for multi-agent systems based on sliding mode control is researched.The main work and innovations of this paper are as follows:Firstly,the research background and significance of this paper are briefly expounded.The development of multi-agent systems control and the research status of distributed fault-tolerant tracking control about multi-agent systems are summarized.The research status of sliding mode control for multi-agent systems are introduced.The mathematical model of Qball-X4 aircraft is established.And the simulation platform of fault-tolerant control for multi-agent systems based on the Qball-X4 aircraft is introduced briefly.Secondly,a distributed robust fault-tolerant control strategy is proposed based on integral sliding mode control and adaptive method for a class of multi-agent tracking systems with actuator loss of effectiveness fault and external disturbance.According to the communication topology between agents,a state tracking error variable is defined.An integral sliding mode surface is designed based on the error variable,and the stability conditions of sliding mode are given.The adaptive method is used to estimate the bound of fault.A distributed sliding mode fault-tolerant controller is presented by using the neighbor state information and the fault bound value,which ensures that the tracking error system can reach and maintain on the sliding mode surface.The simulation results show the feasibility of the presented method by the simulation platform of Qball-X4 aircraft.Then,a distributed output-feedback fault-tolerant control strategy is proposed based on sliding mode observer for a class of multi-agent tracking systems with actuator fault,inherent nonlinearity and external disturbance.The actuator fault is taken as an auxiliary state to establish an augmented system.The sliding mode observer is presented for each follower by using the neighbor output information,and the designed observer is robust to the external disturbance.The stability of the global estimation error system is proved.A distributed output-feedback fault-tolerant controller is designed based on the neighbor output information and the estimation information of actuator fault.It is proved that the global tracking error system can achieve the fault-tolerant tracking control under the proposed control strategy.The control algorithm is applied to the multiple Qball-X4 aircrafts system to verify the effectiveness of the presented method.Finally,a sliding mode fault-tolerant control strategy based on the distributed observer is proposed for the multi-agent tracking systems with problems of actuator fault,sensor fault and unknown input of the leader.For each follower,a state tracking error system is established,and then an augmented tracking error system is obtained by regarding the sensor fault as an auxiliary state.An intermediate variable is introduced,and the distributed observer is designed for the augmented tracking error system and the intermediate variable to estimate fault information and unknown input of the leader simultaneously.Based on the estimation information,a nonlinear sliding mode surface is designed and it is proved that the sliding mode is uniformly ultimately bounded.A distributed sliding mode faulttolerant controller is presented using the neighbor output information and fault estimation information,which ensures that the control system can reach and maintain on the sliding mode surface.The simulation results show the effectiveness of the proposed method.