Semi-global Leader-following Consensus Research Articles

Semiglobal Leader-Following Output Consensus of Discrete-Time Heterogeneous Linear Systems Subject to Actuator Position and Rate Saturation

Motivated by the fact that physical systems are usually subject to actuator position and rate saturation, we consider in this article the semiglobal leader-following output consensus problem of a group of discrete-time heterogeneous linear systems with position and rate-limited actuators by output feedback control law. Distributed observers are designed for followers to estimate the state of the leader and the follower itself, based on which a novel distributed control law is proposed. We show that, via the low gain feedback design technique and output regulation theory, the semiglobal leader-following output consensus of discrete-time heterogeneous linear systems can be achieved by the consensus protocol if each follower is reachable from the leader in a directed communication topology.

Semi-global leader-following output consensus of heterogeneous systems subject to actuator position and rate saturation

We study in this paper a semi-global leader-following output consensus problem for multiple heterogeneous linear systems in the presence of actuator position and rate saturation over a directed topology. For each follower, via the low gain feedback design technique and output regulation theory, both a state feedback consensus protocol and an output feedback consensus protocol are constructed. In the output feedback case, different distributed observers are designed for the informed followers and uninformed followers to estimate the state of the leader and the follower itself. We show that the semi-global leader-following output consensus of heterogeneous linear systems can be achieved by the two consensus protocols if each follower is reachable from the leader in the directed communication topology.

Semi-global leader-following consensus-based formation flight of unmanned aerial vehicles

In this paper, we investigate a formation control problem of multi-agent systems (specifically a group of unmanned aerial vehicles) based on a semi-global leader-following consensus approach with both the leader and the followers subject to input saturation. Utilizing the low gain feedback design technique, a distributed static control protocol and a distributed adaptive control protocol are constructed. The former solves the problem under an assumption that the communication network is undirected, and it depends on the global information of the graph. For the latter, we relax the undirected graph to directed graph. Moreover, an adaptive updating gain is designed to avoid using the global information of the communication network. It is shown that the consensus protocols can solve the semi-global leader-following consensus problem if the leader agent is globally reachable. The results are verified successfully by both simulation and real flight tests.

Semi‐global containment of discrete‐time high‐order multi‐agent systems with input saturation via intermittent control

This study investigates the intermittent semi-global containment of discrete-time high-order multi-agent systems with input saturation. The intermittent semi-global containment protocol is proposed based on discrete-time low-gain state feedback control. Some containment conditions are obtained, and the convergence analysis is given. It is turned out that all the followers beginning from a bounded initial set will asymptotically enter into the convex hull spanned by the leaders under the proposed protocol. Moveover, intermittent semi-global leader-following consensus with input saturation is considered as a special case, and the corresponding result is introduced. Finally, numerical simulations are presented to illustrate the theoretical findings.

Semi-global leader-following output consensus for heterogeneous fractional-order multi-agent systems with input saturation via observer-based protocol

In this paper, semi-global leader-following output consensus problem for heterogeneous fractional-order multi-agent systems with input saturation and external disturbances is investigated. The case where the dynamics are integer-order can be viewed as a special case of fractional-order systems. First, a novel observer-based consensus algorithm is designed to solve the semi-global output consensus problem. It is worth noting that the consensus is semi-global since the set of initial states is bounded. Then, the low gain feedback technique is utilized based on the solution of a parametric algebraic Riccati equation. Moreover, sufficient conditions of output consensus for heterogeneous fractional-order multi-agent systems are derived by using algebraic graph theory, matrix theory and the stability theory of fractional-order systems. It can be proven that the output signals of followers can reach synchronization with the leader’s. Finally, numerical examples are provided to illustrate the effectiveness of our conclusions.

Robust semi-global leader-following practical consensus of a group of linear systems with imperfect actuators

This paper considers the problem of semi-global leader-following consensus of a multi-agent system whose agent dynamics are represented by linear systems. The input output characteristics of the follower agent actuators, such as those of saturation and dead-zone, are imperfect, not precisely known, and subject to the effect of disturbances. Two consensus control algorithms, of the low-and-high gain feedback type and the low gain based variable structure control type, are proposed for solving the consensus problem. It is shown that both of these control algorithms achieve semi-global leader-following practical consensus in the presence of the imperfectness of the actuators when the communication topology among the follower agents is represented by a strongly connected and detailed balanced directed graph and the leader agent is a neighbor of at least one follower agent. The theoretical results are illustrated by numerical simulation.

Semi‐global consensus with position limited and rate disturbances via low gain feedback and integral sliding mode control

In this study, the authors investigate the semi-global leader-following consensus problem of multi-agent systems in the presence of both position saturation and bounded rate disturbances. Each follower agent is described by a general linear dynamic with actuator position saturation and rate disturbances. Based on low-gain feedback design technique and integral sliding mode, discontinuous and continuous control protocols are developed. It is established that semi-global leader-following consensus can be achieved under the assumptions that the system is asymptotically null controllable with bounded controls and the leader agent has a directed path to every follower agent. Simulations are presented to illustrate the results.

Semi-global output consensus of a group of linear systems in the presence of external disturbances and actuator saturation: An output regulation approach

Summary This paper studies the problem of semi-global leader-following output consensus of a multi-agent system. The output of each follower agent in the system, described by a same general linear system subject to external disturbances and actuator saturation, is to track the output of the leader, described by a linear system, which also generates disturbances as the exosystem does in the classical output regulation problem. Conditions on the agent dynamics are identified, under which a low-gain feedback-based linear state-control algorithm is constructed for each follower agent such that the output consensus is achieved when the communication topology among the agents is a digraph containing no loop, and the leader is reachable from any follower agent. We also extend the results to the non-identical disturbance case. In this case, conditions based on both the agent dynamics and the communication topology are identified, under which a low-gain feedback-based linear state-control algorithm is constructed for each follower agent such that the leader-following output consensus is achieved when the communication topology among the follower agents is a strongly connected and detailed balanced digraph, and the leader is a neighbor of at least one follower. In addition, under some further conditions on the agent dynamics, the control algorithm is adapted so as to achieve semi-global leader-following output consensus for a jointly connected undirected graph and the leader reachable from at least one follower. Copyright © 2015 John Wiley & Sons, Ltd.

A continuous leader-following consensus control strategy for a class of uncertain multi-agent systems

In this paper, we study the robust leader-following consensus problem for a class of multi-agent systems with unknown nonlinear dynamics and unknown but bounded disturbances. The control input of the leader agent is nonzero and not available to any follower agent. We first consider a class of high order chain integrator-type multi-agent systems. By employing the robust integral of the sign of the error technique, a continuous distributed control law is constructed using local information obtained from neighboring agents. Using Lyapunov analysis theory, we show that under a connected undirected information communication topology, the proposed protocol achieves semiglobal leader-following consensus. We then extend the approach to a class of more general uncertain multiagent systems. A numerical example is given to verify our proposed protocol.

Semi-Global Leader-Following Consensus of Linear Multi-Agent Systems With Input Saturation via Low Gain Feedback

This paper investigates the problem of leader-following consensus of a linear multi-agent system on a switching network. The input of each agent is subject to saturation. Low gain feedback based distributed consensus protocols are developed. It is established that, under the assumptions that each agent is asymptotically null controllable with bounded controls and that the network is connected or jointly connected, semi-global leader-following consensus of the multi-agent system can be achieved. Numerical examples are presented to illustrate this result.