Youfeng Su

Cooperative Output Regulation of Linear Multi-Agent Systems

In this technical note, we consider the cooperative output regulation of linear multi-agent systems. The overall system consists of two groups of subsystems. While the first group of subsystems can access the exogenous signal, the second cannot. As a result, the problem cannot be solved by the decentralized approach. By devising a distributed observer, we can solve the problem by a dynamic full information distributed control scheme. The problem can also be viewed as a generalization of some results of the leader-following consensus problem of multi-agent systems.

Stability of a Class of Linear Switching Systems with Applications to Two Consensus Problems

In this paper, we first establish a stability result for a class of linear switched systems involving Kronecker product. The problem is interesting in that the system matrix does not have to be Hurwitz at any time instant. This class of linear switched systems arises in the control of multi-agent systems under switching network topology. As applications of this stability result, we give the solvability conditions for both the leaderless consensus problem and the leader-following consensus problem for general marginally stable linear multi-agent systems under switching network topology. In contrast with some existing results, our results only assume that the dynamic graph is uniformly connected.

Cooperative adaptive output regulation for a class of nonlinear uncertain multi-agent systems with unknown leader ☆

Abstract In this paper, we study the cooperative global adaptive output regulation problem for a class of nonlinear uncertain multi-agent systems subject to an uncertain leader system. In comparison with the case where the leader system is known exactly, we need to combine adaptive control and robust control techniques to deal with the unknown parameters in the leader system. By employing a distributed internal model for the multi-agent system, we first convert the problem into a global adaptive robust stabilization problem of a distributed augmented system. Then we further solve the global adaptive stabilization problem of the augmented system by a distributed adaptive control law. Finally, we show that the unknown parameters in the leader system can be exactly estimated provided that the distributed internal model is of minimal order.

Cooperative output regulation of linear multi-agent systems by output feedback ☆

Abstract In this paper, following our recent result on the cooperative output regulation of linear multi-agent systems by a distributed full information state feedback control, we further study the same problem by a distributed measurement output feedback control under certain detectability assumptions. As the problem can be viewed as an extension of the leader-following consensus problem of the linear multi-agent systems, our result contains some existing results on the multi-agent system control as special cases.

Cooperative global output regulation of heterogeneous second-order nonlinear uncertain multi-agent systems

In this paper, we study the cooperative global output regulation problem for a class of heterogeneous second order nonlinear uncertain multi-agent systems. We first introduce a type of distributed internal model that converts the cooperative global output regulation problem into the global robust stabilization problem of the so-called augmented multi-agent system. Then we further globally stabilize this augmented multi-agent system via a distributed state feedback control law, thus leading to the solution of the original problem. A special case of our result leads to the solution of the global leader-following consensus problem for the second order nonlinear multi-agent systems without satisfying the global Lipschitz condition.

Cooperative Global Robust Output Regulation for Nonlinear Uncertain Multi-Agent Systems in Lower Triangular Form

In this paper, we study the cooperative global robust output regulation problem for a class of lower triangular nonlinear uncertain multi-agent systems. We first introduce a type of distributed internal model to convert the cooperative global robust output regulation problem into a global robust stabilization problem of a so-called augmented multi-agent system which is in the block lower triangular form. We then further show that, under a set of standard assumptions, the augmented multi-agent system can be globally stabilized via a distributed state feedback control law by developing a block backstepping technique. A special case of the main result of this paper leads to the solution of the leader-following global robust consensus problem for a class of nonlinear uncertain multi-agent systems.

Cooperative semi-global robust output regulation for a class of nonlinear uncertain multi-agent systems☆

Abstract In this paper, we study the cooperative semi-global robust output regulation problem for a class of minimum phase nonlinear uncertain multi-agent systems. This problem is a generalization of the leader-following tracking problem in the sense that it further addresses such issues as disturbance rejection, robustness with respect to parameter uncertainties. To solve this problem, we first introduce a type of distributed internal model that converts the cooperative semi-global robust output regulation problem into a cooperative semi-global robust stabilization problem of the so-called augmented system. We then solve the semi-global stabilization problem via distributed dynamic output control law by utilizing and combining a block semi-global backstepping technique, a simultaneous high gain feedback control technique, and a distributed high gain observer technique.

Leader-following rendezvous with connectivity preservation and disturbance rejection via internal model approach

Most of the recent results on the leader-following rendezvous problem focus only on the deterministic multi-agent systems without external disturbances and plant uncertainties. In this paper, we will present a novel distributed internal model approach to further study the leader-following rendezvous problem for double-integrator multi-agent systems subject to both external disturbances and plant uncertainties. We provide both the distributed full state feedback control and the distributed partial state feedback control without velocity measurement. In both control schemes, we will give the suitable distributed internal model to convert the rendezvous problem into the stabilization problem with connectivity preserving for their augmented systems. We stabilize the corresponding augmented systems by the high gain feedback control based on a new potential function. Comparing with some recent results, our design can handle a large class of reference signals, external disturbances, and plant uncertainties.

Cooperative Global Output Regulation of Second-Order Nonlinear Multi-Agent Systems With Unknown Control Direction

This technical note addresses the cooperative global output regulation problem for second-order nonlinear multi-agent systems without a priori knowledge of the control direction. We will propose both the graph-dependent and graph-independent distributed controllers based on the combination of the internal model, the Nussbaum-type dynamic gain, and the adaptive control technique. Comparing with some existing results, our novel design can handle the multi-agent system with not only the arbitrary and non-identical unknown control direction but also the uncertain parameter that belongs to any unknown and non-compact set.

Global robust output regulation for nonlinear multi-agent systems in strict feedback form

In this paper, the cooperative global robust output regulation problem for a class of strict feedback nonlinear uncertain multi-agent systems is studied. We first introduce a type of distributed internal model that converts the cooperative global robust output regulation problem into a global robust stabilization problem of a so-called augmented multi-agent system which is in block lower triangular form. We then further present a set of sufficient conditions under which the augmented multi-agent system is globally stabilizable by a distributed state feedback control law.