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In this article, we study the cooperative output regulation problem for heterogeneous linear multi‐agent systems by the distributed sampled‐data control approach. We consider two cases. The first case is that the state of the leader system is constant. For this case, we show that the cooperative output regulation problem is solvable exactly by a distributed aperiodic sampled‐data output feedback control law. The second case is that the state of the leader system is time‐varying with bounded derivative. For this case, we further show that the problem is solvable practically by a distributed aperiodic sampled‐data output feedback control law in the sense that the steady‐state regulated output can be made arbitrarily small. Finally, we give two examples to illustrate our results. [ABSTRACT FROM AUTHOR]

In this paper, we study the asymptotic output tracking problem for a class of minimum phase uncertain linear discrete-time multi-agent systems over jointly connected digraphs. As the systems contain arbitrarily large uncertain parameters, the robust feedback control technique does not work. We develop a distributed adaptive control law composed of a distributed observer and a purely decentralised adaptive control law. We first establish a stability result for a class of linear switched systems, which extends the existing results. This stability result leads to a novel distributed observer for the leader system which estimates the leader's signal using the output of the leader system locally and passes the estimated leader's signal to each follower. We then further show that the distributed adaptive control law solves our problem under some mild conditions. An example is used to illustrate the effectiveness and generality of our approach. [ABSTRACT FROM AUTHOR]

This technical communique studies the robust output regulation problem of uncertain discrete-time linear systems by quantized output feedback control. We show that, under the same assumptions as those that guarantee the solvability of the robust output regulation problem by a dynamic output feedback control law, our problem is also solvable by a dynamic quantized output feedback control law as long as the quantization density is greater than certain explicitly specified lower bound. [ABSTRACT FROM AUTHOR]

Summary: In this paper, we study the event‐triggered global robust practical output regulation problem for a class of nonlinear systems in output feedback form with any relative degree. Our approach consists of the following three steps. First, we design an internal model and an observer to form the so‐called extended augmented system. Second, we convert the original problem into the event‐triggered global robust practical stabilization problem of the extended augmented system. Third, we design an output‐based event‐triggered control law and a Zeno‐free output‐based event‐triggered mechanism to solve the stabilization problem, which, in turn, leads to the solvability of the original problem. Finally, we apply our result to the controlled hyperchaotic Lorenz systems. [ABSTRACT FROM AUTHOR]

In this paper, we consider the event-triggered cooperative robust practical output regulation problem for a class of linear minimum-phase multi-agent systems. We first convert our problem into the cooperative robust practical stabilization problem of a well defined augmented system based on the distributed internal model approach. Then, we design a distributed event-triggered output feedback control law together with a distributed output-based event-triggered mechanism to stabilize the augmented system, which leads to the solvability of the cooperative robust practical output regulation problem of the original plant. Our distributed control law can be directly implemented in a digital platform provided that the distributed triggering mechanism can monitor the continuous-time output information from neighboring agents. [ABSTRACT FROM AUTHOR]

In this paper, we study the leader-following attitude consensus problem for multiple rigid body systems by a distributed unit quaternion-based attitude feedback control law. The control law is based on the certainty equivalence principle and contains a distributed observer for estimating the state of the leader and an auxiliary system compensating for the unavailability of the angular velocity. It is shown that the problem is solvable under the standard assumption that each follower can access the information from the leader through a directed path. [ABSTRACT FROM AUTHOR]

In this paper, we study the cooperative output regulation problem for linear time-delay multi-agent systems subject to jointly connected switching network. We first establish two lemmas that lay the foundation for solving the problem and then present the solution to the problem by both the dynamic state feedback control law and the dynamic measurement output feedback control law. Our results not only extend the existing results on linear multi-agent systems without time-delay to linear time-delay multi-agent systems, but also lead to the solution of the leader-following consensus problem of some typical linear time-delay multi-agent systems. [ABSTRACT FROM AUTHOR]

This paper studies the flocking with connectivity preservation problem of multiple double integrator systems subject to a class of external disturbances. We solve the problem by a distributed dynamic position feedback control law under the standard assumptions. Our approach is a combination of the potential function technique and observer design. Our result also includes some existing results as special cases. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: This paper generalizes our recent results on global robust output regulation of output feedback systems with integral input-to-state stable (iISS) inverse dynamics in two aspects. First, we consider the general relative degree case instead of the unity relative degree case. For this purpose, the one step approach proposed previously has to be generalized to a recursive approach. Second, we allow the exosystem to be uncertain. For this purpose, we need to introduce an adaptive control technique to estimate the unknown parameter vector in the exosystem. A convergence analysis of the estimated parameter vector will also be given. [Copyright &y& Elsevier]

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. [Copyright &y& Elsevier]

Abstract: In this paper, we study both the leaderless consensus problem and the leader-following consensus problem for linear discrete-time multi-agent systems under switching network topology. Under the assumption that the system matrix is marginally stable, we show that these two consensus problems can be solved via the state feedback protocols, provided that the dynamic graph is jointly connected. Our result will contain several existing results as special cases. The proof is based on the stability analysis of a class of linear discrete-time switched systems which may have some independent interest. [Copyright &y& Elsevier]

Abstract: In this note, we investigate the possibility of simplifying the connectivity verification for multi-agent systems with proximity graphs and the linear feedback protocol. A Lyapunov-like approach is developed for analyzing the monotonicity of the largest edge length in the network. Based on this approach, we provide an initial-connectivity-based sufficient condition for dynamic connectivity. In particular, when each initial node degree is not less than three fourth of the graph order, initial network connectivity implies dynamic connectivity. [Copyright &y& Elsevier]

The global robust servomechanism problem (alternatively, global robust output regulation problem) for lower triangular systems has been studied for two special cases. The first case assumes that the systems only contain polynomial nonlinearities, and the second case limits the exogenous signals and the unknown parameters to be within a known bounded set. This paper presents the solvability conditions of the global robust servomechanism problem for the lower triangular systems for the most general case where neither of the above two assumptions is needed. Our approach consists of two steps. In the first step, we convert the problem into a global adaptive regulation problem for lower triangular systems subject to both dynamic and static uncertainties. In the second step, we derive the solvability conditions of the problem by appealing to the recent result on the solvability of the global adaptive regulation problem for lower triangular systems with both dynamic and static uncertainties. [Copyright &y& Elsevier]

In this paper, we study the output regulation problem for linear systems by the aperiodic sampled-data control approach. Suppose the problem is solvable by a continuous-time static state feedback control law and a continuous-time dynamic output feedback control law. Then, we first show that, if the exogenous signal is constant, then the output regulation problem is solvable exactly by both the sampled-data static state feedback control law and the sampled-data dynamic output feedback control law. If the exogenous signal is time-varying with bounded derivative, then we further show that the problem is solvable practically by both the sampled-data static state feedback control law and the sampled-data dynamic output feedback control law. [ABSTRACT FROM AUTHOR]

Abstract: The parameter convergence of nonlinear adaptive control systems is an important yet not well addressed issue. In this paper, using the global robust output regulation problem of output feedback systems with unknown exosystems as a platform, we will show that the well known persistency of excitation (PE) condition still guarantees the convergence of the estimated parameter vector to the true parameter vector. Moreover, the PE condition will be satisfied if the internal model is minimal in certain sense. [Copyright &y& Elsevier]