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In this note, we first present a framework for designing a distributed control law to solve a cooperative control problem of nonlinear multiagent systems with a nonlinear leader system. The distributed control law is composed of a purely decentralized control law and a distributed observer for the leader system, based on the certainty equivalence principle. Then, we establish a sufficient condition to guarantee the existence of a distributed observer for a class of nonlinear autonomous systems. The framework is then applied to solve the leader-following consensus problem for a class of high-order nonlinear heterogeneous multiagent systems subject to external disturbances. Our design is illustrated by an example with the Van der Pol system as the leader system. [ABSTRACT FROM AUTHOR]

In this paper, we study the cooperative global robust practical output regulation problem for a class of second-order uncertain nonlinear multiagent systems via a distributed event-triggered state feedback control strategy. Compared with the existing work, one of the main challenges is that we need to design two distributed internal models to learn both the desired steady-state state and steady-state input for each agent. Moreover, to obtain a directly implementable digital control law, the two distributed internal models of each agent only depend on the sampled states of the neighboring agents and itself. As a result, the resulting augmented system is more complicated, and the control law needs to be recursively designed. To overcome the difficulty, we propose a novel distributed event-triggered control law and a novel distributed event-triggered mechanism to deal with our problem. By adjusting a design parameter in the proposed event-triggered mechanism, we show that the Zeno behavior does not happen and the ultimate bound of the tracking error can be made arbitrarily small. Our design will be illustrated by two examples. [ABSTRACT FROM AUTHOR]

In this paper, we study the cooperative global robust output regulation problem for nonlinear multiagent systems in output feedback form with any relative degree subject to directed switching networks. Through the augmentation by a distributed internal model and a distributed observer of the given system, we first convert the original problem into the global robust stabilization problem of the so-called extended augmented system, which is a multi-input-coupled switched system. Then, we establish a few technical lemmas to lay the foundation for constructing a switching control law and the corresponding multiple Lyapunov functions for the switched system. Then, we present the solvability conditions of our problem via the multiple Lyapunov functions and average dwell time method. The main result will be applied to the leader-following synchronization problem for a group of hyperchaotic Lorenz multiagent systems with a directed switching network. [ABSTRACT FROM PUBLISHER]

This note studies the global robust output regulation problem for a class of nonlinear systems by an output-based event-triggered control law. First, we convert the problem into the event-triggered global robust stabilization problem of a well-defined augmented system based on the internal model approach. Then, we design an output-based event-triggered control law together with an output-based event-triggered mechanism to solve the stabilization problem, which in turn leads to the solution to the original problem by an output-based event-triggered control law. Finally, we illustrate our approach by an example. [ABSTRACT FROM AUTHOR]

In this technical note, we study the cooperative global robust output regulation problem for the unity relative degree nonlinear multi-agent system in normal form with a nonlinear leader system. The same problem was studied recently under the assumptions that the system contains only polynomial nonlinearities, the leader system is linear and the communication network is undirected. By employing a distributed nonlinear internal model, we will construct a control law that accommodates non-polynomial nonlinearities, nonlinear leader systems, and directed communication networks. Our result will be illustrated by an example with the well known Van der Pol oscillator as the leader system. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

In this technical note, we consider the cooperative global robust output regulation problem for nonlinear multi-agent systems in output feedback form by distributed output feedback control. The main result can be summarized as follows: if the information of the leader can reach every follower through a path and the communication flows among the followers are bidirectional, then the problem can be solved by a distributed output feedback control law if the global robust output regulation problem for each subsystem can be solved by an output feedback control law. [ABSTRACT FROM AUTHOR]

The cooperative robust output regulation problem for a class of second-order nonlinear multiagent systems with an exactly known exosystem has been studied recently. This paper further studies the same problem for the same class of systems subject to an unknown exosystem. We first show that the problem can be converted into the adaptive stabilization problem for an augmented system composed of the given multiagent system and the distributed internal model. Due to the unknown parameters in the exosystem, the augmented system is a nonlinear multi-input system with both linearly parameterized uncertainties and norm-bounded nonlinear uncertainty. By combining the adaptive control technique and the robust control technique, we will solve our problem by a distributed adaptive robust state feedback controller. [ABSTRACT FROM AUTHOR]

The cooperative output regulation problem for linear uncertain multi-agent systems was studied in refid="ref14"/ via an internal model approach under the assumption that the information graph of the system contains no cycle. In this technical note, we further show that the no-cycle assumption can be removed if all subsystems of the follower have the same nominal dynamics. Moreover, by directly making use of the property of the internal model, we provide a more straightforward proof than the one in refid="ref14"/ in that we don't need to verify the satisfaction of certain matrix equations. [ABSTRACT FROM AUTHOR]

In this technical note, we study the global disturbance rejection problem of nonlinear systems in lower triangular form with unknown exosystem via state feedback control. The problem is dealt with in two steps. In the first step, an augmented system composed of the given plant and an internal model is constructed. Owing to the presence of the unknown parameter in the exosystem, the augmented system contains both nonlinearly and linearly parameterized uncertainties. In the second step, the stabilization of the augmented system is solved by an approach integrating both robust and adaptive techniques. The solution of the stabilization problem of the augmented system in turn leads to the solution of the global disturbance rejection problem of the original system. Further, the convergence issue of an estimated unknown parameter vector is also discussed. [ABSTRACT FROM PUBLISHER]

In this note, the robust output regulation problem of a multi-agent system is considered. An internal model based distributed control scheme is adopted to achieve the objectives of asymptotic tracking and disturbance rejection in an uncertain multi-agent system where both the reference inputs and disturbances are generated by an exosystem. [ABSTRACT FROM AUTHOR]

This technical note deals with the problem of robust controller design of uncertain discrete time-delay systems subject to control input saturation and bounded external disturbances. A sufficient condition is obtained, which guarantees the existence of state feedback controllers and an admissible initial condition domain such that the resulting closed-loop system is uniformly exponentially convergent to a ball with certain exponential decay rate for every initial condition emanating from the admissible domain. An iterative linear matrix inequality relaxation scheme can be used to construct desired state feedback controllers. A simulation example is provided to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]