Output Consensus Of Heterogeneous Multi-Agent Systems

For decades,cooperative control of multi-agent systems(MAS)has been an active research area given its broad and increasing applications in biology,physics,and engineering field.One of the basic cooperative control problems is the consensus problem,which is to assure that all agents reach agreement on a certain common trajectory(leaderless consensus)or follow the trajectory of a leader node(leader-follower consensus).For the communication network with one single leader,the control objective is to synchronize the trajectory of each follower to that of the leader.This is usually referred to as the leader-follower tracking problem.For the communication network with multiple leaders,the control objective is to drive each follower into the convex hull spanned by multiple leaders.This is usually referred to as the containment control problem.A rich body of literature has been developed on state consensus of homogeneous MAS,in which all agents have identical dynamics.However,in many practical applications,the agents are heterogeneous in that the dynamics and even state-space dimensions of the agents are different.For these systems,state consensus is meaningless.Therefore,distributed output consensus of heterogeneous MAS has attracted compelling attention in the literature.Controller design for heterogeneous MAS is complicated by the fact that the agents have different system dynamics and so the standard Kronecker product cannot be used in the closed-loop system dynamics.The upshot is that the closed-loop dynamics has the local controller design and the global graph properties intermingled in a very complex manner.Design of suitable local distributed protocols is consequently difficult.In this thesis,we will investigate the output consensus of heterogeneous MAS.In the first main part of this thesis,we have considered the output regulation of linear heterogeneous MAS with one single leader.The main results are summarized as follows:1.A unified approach to the design of output consensus protocols for linear heterogeneous MAS,using neighbors' relative output measurements,is provided by formulating and solving a suitable local (?)-gain design problem.This (?)-gain design problem can by solved by local design algorithms that guarantee the local gains are bounded by a certain value depending on the global graph structure.2.The local sufficient conditions for the existence of the three control protocols are derived.Local design procedures are addressed,respectively.The dynamic compensator employed in each approach incorporates only one copy of the leader' dynamics,regardless of the dimensions of the outputs.This results in lower-dimensional and computationally inexpensive compensator and controller for systems with high-order outputs,compared to the p-copy internal model principles.3.The dynamic output-feedback control protocol addresses a more challenging case of heterogeneous non-introspective agents,in which the relative output information of each agent and its neighbors,is the only available information.In the second main part of this thesis,we have studied the output containment control for a class of networked linear heterogeneous MAS.Compared with the previous literature,the main contributions are summarized as follows:1.This is the first time that the output containment problem of heterogeneous MAS is addressed.The heterogeneous MAS considered are composed of agents with different system matrices and state dimensions.2.The output containment problem for heterogeneous MAS is solved using two different control protocols,namely,full-state feedback and static output-feedback.Compared to the feedforward approach used in the existing literature,our protocols do not require state information of leaders.Moreover,only the relative output information of each follower with respect to its neighbors is exchanged in the communication network.3.Since the feedforward approach requires a feedforward gain that depends on the system parameters,it cannot accommodate uncertainties.In contrast,by using the internal model principle,our protocols are more robust against parameter variation.4.Under certain assumptions,unified approaches to the design of the two proposed control protocols are provided by formulating as a certain state-feedback problem and a static output-feedback problem,respectively.In the third mian part of this thesis,we have investigated the adaptive output containment control of heterogeneous MAS,where the leaders' dynamics are only known to the neighboring followers.Compared with the previous literature,the main contributions are summarized as follows:1.Local adaptive observers are first proposed at each follower to estimate the leaders' dynamics.Then,an adaptive algorithm solves the associated output regulator equations online in real time.2.Two different control protocols using state-feedback and dynamic output-feedback are proposed at each follower.Both protocols use the estimated leaders' dynamics and the adaptive solutions to the output regulator equations.3.Proposed local control protocols do not need any global communication topology information,and only depend on the local state or output information.Therefore,these designs are fully distributed.