Discrete-time Networked Multi-agent Systems Research Articles

Observer-Based Consensus Control for Discrete-Time Multiagent Systems With Coding-Decoding Communication Protocol.

In this paper, the consensus control problem is investigated for a class of discrete-time networked multiagent systems (MASs) with the coding-decoding communication protocol (CDCP). Under a directed communication topology, an observer-based control scheme is proposed for each agent by utilizing the relative measurement outputs between the agent itself and its neighboring ones. The signal delivery is in a digital manner, which means that only the sequence of finite coded signals is sent from the observer to the controller. To be specific, the observed data is encoded to certain codewords by a designed coder via the CDCP, and the received codewords are then decoded by the corresponding decoder at the controller side. The purpose of the addressed problem is to design an observer-based controller such that the close-loop MAS achieves the expected consensus performance. First, with the help of the input-to-state stability theory, a theoretical framework for the detectability is established for analyzing and designing the CDCP. Then, under such a communication protocol, some sufficient conditions for the existence of the proposed observer-based controller are derived to guarantee the asymptotic consensus of the MASs. In addition, the controller parameter is explicitly determined in terms of the solution to certain matrix inequalities associated with the information of the communication topology. Finally, a simulation example is given to demonstrate the effectiveness of the developed control strategy.

Consensus Tracking of Heterogeneous Discrete-Time Networked Multiagent Systems Based on the Networked Predictive Control Scheme.

This paper studies the problem of consensus tracking for heterogeneous discrete-time networked multiagent systems (NMASs) with network-induced communication delay. By introducing the networked predictive control scheme, novel consensus tracking protocols are designed to ensure that states of the NMASs follow the external reference signal. One of the agents is defined as the leader agent, all the other agents are defined as the followers, and the external reference signal is always known by the leader agent, both cases where the external reference signal is available and unavailable to the follower agents are discussed in this paper. The necessary and sufficient conditions for the novel consensus tracking protocols are proposed based on algebraic and graph theory. Numerical examples are given to validate the theoretical results.

Distributed algorithm for dissensus of a class of networked multiagent systems using output information

In this paper, a distributed algorithm is developed to solve the dissensus of a class of networked multiagent systems only using output information. By introducing a gauge transformation, the dissensus problem is transformed to the problem of demonstrating that (A, B, C) is stabilizable and detectable. If the networked multiagent systems can reach dissensus, the signed digraph is structurally balanced containing a spanning tree. Furthermore, by solving a Riccati equation, the necessary condition becomes a necessary and sufficient condition. Finally, two examples are provided to illustrate our results. There are three main contributions in this paper: (1) a distributed algorithm with output information is introduced to deal with the difficulty of obtaining relative full-state observations; (2) the undirected communication graph is extended to the signed digraph which is more practical in physical implementations; (3) the method established in this paper is also applicable to discrete-time networked multiagent systems by using a gauge transformation, which further demonstrates the generality of our results.

Consensus for networked multi-agent systems with unknown communication delays

The problem of consensus for linear discrete-time networked multi-agent systems with directed topologies and communication delays is investigated in this paper. The communication delays are assumed to be constant but unknown. A consensus protocol is designed to compensate for the unknown delays based on the networked predictive control scheme. A sufficient condition for the consensus of multi-agent systems is derived. Finally, a numerical example is given to illustrate that the consensus protocol proposed in this paper is effective.

Consensus of high-order discrete-time linear networked multi-agent systems with switching topology and time delays

In this paper, the consensus problem for high-order discrete-time networked multi-agent systems (D-NMAS) is investigated by distributed feedback protocols. By constructing the self-feedback matrix and the neighbouring feedback matrix for networks, consensus protocols are designed under three different cases and the corresponding convergence analysis is provided. Consensus convergence results of networks are provided by three final consensus values, which are related to self-feedback matrices, initial states of networks and the topology of networks, not related to time delays. In the first case where a directed network with a fixed topology is concerned, the high-order discrete-time consensus problem is studied as an example, and a sufficient and necessary condition is obtained. In the scenario with directed networks with switching topology, a sufficient condition guaranteeing the consensus of high-order D-NMAS is derived, after the consensus analysis is transformed into stability analysis. As for directed networks with switching topology and time delays, the discrete-time stability model with time delays is converted into a general discrete-time stability model by an augmented method and the sufficient condition is provided to achieve consensus for directed networks. Furthermore, the sufficient conditions determining the neighbouring feedback matrix are independent of the number of agents. Two numerical examples are provided to demonstrate the correctness and effectiveness of the theoretical results.

Consensus of networked multi-agent systems with diverse time-varying communication delays

In this paper, the problem of consensus for discrete-time networked multi-agent systems (NMASs) with a directed topology and diverse time-varying communication delays is investigated. By introducing the networked predictive control scheme, the predictions of states at current time, instead of available outdated states, are exploited to design a distributed consensus protocol, which compensates for communication delays actively. For NMASs with identical linear agents and bounded time-varying communication delays, necessary and sufficient conditions of the consensus are provided. Numerical simulations are given to compare the proposed networked predictive control method with the standard non-predictive way, and demonstrate the effectiveness of theoretical results.

Consensus of Discrete-Time Linear Networked Multi-Agent Systems With Communication Delays

This technical note investigates the problem of consensus for discrete-time networked multi-agent systems (NMASs), where information is exchanged through the network with a communication delay. Based on the networked predictive control scheme and the dynamic output feedback, a novel distributed protocol is proposed to compensate for the network delay actively. For NMASs with a directed topology and non-uniform agents, sufficient conditions of the consensus are obtained. A numerical simulation demonstrates effectiveness of the proposed theoretical results.

Consensus of networked multi-agent systems with communication delays based on the networked predictive control scheme

The consensus problem of discrete-time networked multi-agent systems (NMASs) with a communication delay is investigated in this article, where the dynamics of agents described by discrete-time linear time-invariant systems can be either uniform or non-uniform. For the NMASs with a directed topology and constant delay, a novel protocol based on the networked predictive control scheme is proposed to compensate for communication delay actively. Using algebraic graph theories and matrix theories, necessary and/or sufficient conditions of achieving consensus are obtained, which indicates that, under the proposed protocol, the consensus is independent of the network delay and only dominated by agents' dynamics and communication topology. Meanwhile, the protocol design and consensus analysis are also presented in the case of no network delay. Simulation results are further presented to demonstrate the effectiveness of theoretical results.

Consensus of networked multi-agent systems via the networked predictive control and relative outputs

This paper investigates the consensus problem of discrete-time networked multi-agent systems (DNMASs) with a directed topology and communication delay, where exact state and output of each agent are not measured, and yet output differences between agent and its neighboring ones (relative outputs for short) are available. Based on the networked predictive control scheme and relative output data, a novel protocol is proposed to overcome the effect of delay on the consensus actively. Moreover, for the DNMASs with a fixed topology and constant communication delay, delay-independent necessary and/or sufficient conditions of achieving consensus are obtained, which reveal that the essence of dominating the consensus is agents' dynamics and communication topology. Simulation results further demonstrate the effectiveness of theoretical results.