Research On Robust And Output Feedback Consensus Of Multi-agent Systems With Input Saturation

The consensus control problem of multi-agent systems(MASs),as one of the most basic and important problem of distributed cooperative control,has been widely concerned by scholars in different fields.The theory of consensus control is widely used in industrial applications and the field of network science,such as distributed attitude control of multiple spacecraft,cooperative motion control of multi-vehicle systems,traffic networks,social networks,and so on.On the other hand,the control input of the system can not reach the ideal strength at any time,because of the saturation of energy or limitation of its mechanical structure,so actuator saturation constraints are ubiquitous in practical engineering applications.If we do not adopt the appropriate control strategy for the input saturation phenomenon,it will often lead to the degradation of system control performance,and even lead to system instability,resulting in serious consequences.Therefore,the study on the control of input saturation MASs is not only a challenge in theoretical analysis,but also of great significance to industrial applications.However,the results on consensus control for input-saturated MASs are very limited.In this dissertation,with low gain feedback as the core tool,combined with sliding mode control,event-triggered control,robust control,and so on,the semi-global robust consensus,semi-global output feedback consensus,and semiglobal output consensus of input-saturated MASs are studied;the expansions of the consensus problem of MASs with input saturation under various communication topologies,dynamics and various constraints are explored.The main contributions of this dissertation are as follows:Research on the semi-global leader-follower consensus of MASs with position saturation and rate disturbances.The dynamic of each follower agent can be described as a general linear system with actuator position saturation and rate disturbance.Based on the low-gain feedback design method and sliding mode control theory,discontinuous and continuous control protocols are developed.It overcomes the adverse effects of position saturation and the unknown bounded disturbance on the rate of the system at the same time.Discontinuous and continuous protocols are shown to achieve semi-global leader-follower consensus.Research on semi-global adaptive event-triggered output consensus of heterogeneous linear MASs subject to input saturation.An adaptive event-triggered controller is designed for input-saturated heterogeneous MAS with a leader.First of all,by applying the adaptive control method,the controller design process is independent of the global topology information.Secondly,by establishing the estimation of the real state of the neighbor,the self-trigger of the controller is realized,which overcomes the disadvantage that the traditional consensus controllers need continuous communication to monitor the state of the neighbor agent.It is proved that semi-global leader-follower output consensus can be achieved.This dissertation further discusses a more general situation,that is,agents directly connected to leaders can not obtain complete leader output information,but can only obtain partial output information.In this case,by introducing distributed observer technology to compensate for the missing information in the interaction of the follower agents,so that the system can reach semi-global output consensus.The absence of the Zeno behavior is also established for these controllers.Research on semi-global fully distributed event-triggered output feedback consensus of MASs with input saturation on a general directed graph.To overcome the difficulties in theoretical analysis caused by a directed graph,it is necessary to design an adaptive parameter with a special structure,which makes it more complex to extend state feedback to output feedback.Therefore,firstly,this dissertation designs a fully distributed eventtriggered output feedback controller for general linear MASs to achieve global consensus.Then,on this basis,a fully distributed event-triggered output feedback controller is developed for the input-saturated MAS,the theoretical difficulties caused by complex adaptive parameters are overcome by designing a high-gain observer,it is proved that the system can reach semi-global consensus.The absence of the Zeno behavior is also established for these controllers.Research on semi-global robust output feedback consensus of uncertain MASs subject to input saturation.For the input-saturated uncertain MASs,a new type of output feedback controller is developed,which only needs the relative output information of agents and has no controller information interaction.Through theoretical analysis,the effectiveness of lowgain feedback control is proved creatively in the framework of small-gain Lemma,and it is proved that the system can reach semi-global consensus.Research on semi-global robust consensus of uncertain discrete-time MASs subject to input saturation.Because the new type output feedback controller design method for continuous MASs can not be directly applied to discrete-time MASs,this dissertation designs a discrete output feedback controller without controller information exchange for discrete input saturated MAS.Through skillful parameter design,the difficulty of extending from continuous system to discrete system is overcome,and it is proved that the system can reach semi-global consensus.