Robust iterative learning protocols for finite-time consensus of multi-agent systems with interval uncertain topologies

This paper is devoted to the robust finite-time output consensus problems of multi-agent systems under directed graphs, where all agents and their communication topologies are subject to interval uncertainties. Distributed protocols are constructed by using iterative learning control (ILC) algorithms, where information is exchanged only at the end of one iteration and learning is used to update the control inputs after each iteration. It is proved that under ILC-based protocols, the finite-time consensus can be achieved with an increasing number of iterations if the communication network of agents is guaranteed to have a spanning tree. Moreover, if the information of any desired terminal output is available to a portion (not necessarily all) of the agents, then the consensus output that all agents finally reach can be enabled to be the desired terminal output. It is also proved that for all ILC-based protocols, gain selections can be provided in terms of bound values, and consensus conditions can be developed associated with bound matrices. Simulation results are given to demonstrate the effectiveness of our theoretical results.     

带有观测器的广义多智能体系统二分一致性

本文研究了带有观测器的广义多智能体系统的二分一致性问题.根据符号图的特性,提出了一种基于广义观测器的分布式二分一致性控制协议.以广义系统稳定性理论和代数图论为主要研究工具,分析并得到了广义多智能体系统实现二分一致性的充分条件.利用广义观测器的相对和绝对信息设计了两种新的二分一致性控制协议.数值仿真验证了理论结果的准确性和有效性.     

Finite-time consensus for stochastic multi-agent systems

In this article, we study the finite-time consensus in probability for stochastic multi-agent systems. First, we give the nonlinear consensus protocol for multi-agent systems with Gaussian white noise, and define the concept of finite-time consensus in probability. Second, we prove that multi-agent systems can achieve the finite-time consensus in probability under five different kinds of communication topologies by using graph theory, stochastic Lyapunov theory and probability theory. Finally, some simulation examples are provided to illustrate the effectiveness of the theoretical results.     

具有通信时延的二阶多智能体系统有限时间一致性跟踪控制

针对具有通信时延的二阶多智能体系统的有限时间一致性控制问题,分别研究了具有固定拓扑和切换拓扑网络结构情形下的二阶多智能体系统的有限时间一致性。为使多智能体系统能在有限时间内可以达到一致,引入一致性控制增益矩阵并设计了相应的基于相对位置和相对速度的时延状态误差有限时间一致性控制算法,利用系统模型转换,泛函微分方程稳定性理论和有限时间Lyapunov稳定性定理得到了使系统在有限时间内达到一致跟踪的最大时延上界值。最后,仿真实验结果验证了所得理论的正确性和有效性。     

Robust finite-time consensus tracking for second-order multi-agent systems with input saturation under general directed communication graphs

In this paper, we study the global finite-time consensus tracking problem for uncertain second-order multi-agent systems subject to input saturation. The communication graphs are allowed to be general directed graphs. Sliding-mode observer-based distributed controllers are proposed such that global finite-time consensus tracking is achieved with bounded control inputs. Only relative state or output measurements are used in the proposed controller which reduces the communication requirement on the agents. Simulation examples are given to illustrate the effectiveness of the proposed control strategies.     

Distributed robust finite-time nonlinear consensus protocols for multi-agent systems

This paper investigates the robust finite-time consensus problem of multi-agent systems in networks with undirected topology. Global nonlinear consensus protocols augmented with a variable structure are constructed with the aid of Lyapunov functions for each single-integrator agent dynamics in the presence of external disturbances. In particular, it is shown that the finite settling time of the proposed general framework for robust consensus design is upper bounded for any initial condition. This makes it possible for network consensus problems to design and estimate the convergence time offline for a multi-agent team with a given undirected information flow. Finally, simulation results are presented to demonstrate the performance and effectiveness of our finite-time protocols.     

异构多智能体系统有限时间一致性分析

研究二阶智能体速度不可测情况下由一阶和二阶智能体构成的异构多智能体系统有限时间一致性问题。在固定拓扑结构下,给出了异构系统实现一致性的控制协议,通过LaSalle不变集原理和齐次控制方法得到了异构系统有限时间一致性的充分条件;在切换拓扑结构下,给出了异构系统一致性的控制协议,得到了异构系统有限时间一致性的充分条件。仿真结果验证了相关结果的有效性。     

Observer-based prescribed-time consensus control for heterogeneous multi-agent systems under directed graphs

This work studies the prescribed-time robust consensus tracking problem of heterogeneous multi-agent systems over directed graphs. Aiming at multi-agent systems with a static leader and only matched disturbances, a distributed observer-based consensus algorithm is developed, to ensure that the tracking errors converge to zero accurately in prescribed time. For the case of multi-agent systems with a dynamic leader and mismatched/matched disturbances, an adaptive strategy based on a distributed observer and a disturbance observer is designed by the dynamic damping reciprocal technology. Such strategy can avoid the numerical singularity, adapt to the situation that the upper bounds of the disturbances are unknown, and assure that the tracking errors converge to an adjustable neighborhood of zero within prescribed time. Finally, simulations are given to verify the effectiveness of the proposed control strategies.     

考虑量化的多智能体系统数据驱动双向一致性控制

针对未知动力学模型非线性离散时间多智能体系统,在信息传递过程中的数据量化问题,以及智能体之间的合作与竞争关系,提出了一种数据驱动控制算法,实现了多智能体系统的双向一致性跟踪控制.首先,利用紧凑形动态线性化(CFDL)方法,将未知动力学模型的非线性智能体转化为含有时变参数的数据模型,并通过设计性能指标函数获得时变参数的估...     

Stationary average consensus protocol for a class of heterogeneous high-order multi-agent systems with application for aircraft

This paper investigates the stationary average consensus problem for a class of heterogeneous-order multi-agent systems. The goal is to bring the positions of agents to the average of their initial positions while letting the other states converge to zero. To this end, three different consensus protocols are proposed. First, based on the auxiliary variables information among the agents under switching directed networks and state-feedback control, a protocol is proposed whereby all the agents achieve stationary average consensus. In the second and third protocols, by resorting to only measurements of relative positions of neighbouring agents under fixed balanced directed networks, two control frameworks are presented with two strategies based on state-feedback and output-feedback control. Finally, simulation results are given to illustrate the effectiveness of the proposed protocols.     

Group consensus of multi-agent systems with directed information exchange

We discuss a new consensus problem – a group consensus problem – in networks of dynamic agents. For a complex network consisting of several sub-networks owing to physical quantities or task distributions, it is concerned with this case that the agents in a sub-network share a consistent value while there is no agreement between any two sub-networks. When the information exchange is directed, a novel consensus protocol is designed to solve the group consensus problem. The convergence analysis is discussed and several criteria are established based on graph theories and matrix theories. Simulation results are presented to demonstrate the effectiveness of the theoretical results.     

二阶混杂多智能体系统的安全二分一致性

本文在合作–竞争网络下针对一类由二阶连续时间个体和离散时间个体构成的混杂多智能体系统, 研究了系统中存在恶意个体情况下的安全二分一致性问题. 首先, 在假设智能体的恶意邻居数量上限已知的情况下, 基于删除邻居信息中极端值的思想, 设计了一种安全二分一致性容错算法. 其次, 基于鲁棒图性质进行系统转换, 运用图论、矩阵论等分析工具得到了系统实现安全二分一致性的图条件. 最后, 通过仿真实例验证了所得结果的有效性.关键词: 混杂多智能体系统; 恶意个体; 安全二分一致性; 容错算法     

Robust consensus algorithm for second-order multi-agent systems with external disturbances

This article investigates the problem of robust consensus for second-order multi-agent systems with external disturbances. Based on a non-smooth backstepping control technique, a class of novel continuous non-smooth consensus algorithms are proposed for the multi-agent network with/without communication delays. The controller design is divided into two steps. First, for the kinematic subsystem, the velocity is regarded as a virtual input and designed such that the states consensus can be achieved asymptotically. Then for the dynamic subsystem, a finite-time control law is designed such that the virtual velocity can be tracked by the real velocity in a finite time. Under the proposed control law, it is shown that if the communication topology graph contains a directed spanning tree, the states consensus can be achieved asymptotically in the absence of disturbances. In the presence of disturbances, the steady-state errors of any two agents can reach a small region around the origin. By building a relationship between control parameters and the bound of steady tracking errors, it is demonstrated that the disturbance rejection performance of the resulting closed-loop system can be enhanced by adjusting the fractional power in the non-smooth controller. Finally, an example is given to verify the efficiency of the proposed method.     

Distributed fuzzy adaptive event-triggered finite-time consensus tracking control for uncertain nonlinear multi-agent systems with asymmetric output constraint

This article investigates the consensus problem for uncertain nonlinear multi-agent systems (MASs) with asymmetric output constraint. Different from BLF-based constraint consensus tracking control, a novel approach based on nonlinear state-dependent function is proposed to solve the asymmetric output constraint, which need not convert output constraint into tracking error bound. First-order sliding mode differentiator is incorporated into each step of backstepping control design to reduce computation burden. Further, in combination of proposed event-triggered mechanism based on time-varying threshold, a distributed fuzzy adaptive event-triggered finite-time consensus method is developed. It can ensure that the consensus tracking error tends to a small neighbor in a finite time and the asymmetric output constraint of each subsystem is not violated. Two simulations are given to demonstrate the effectiveness of control method.     

基于一类连续非线性函数的多智能体系统有限时间一致性

针对存在时滞的多智能体系统,提出了基于一类连续非线性函数的有限时间一致性算法.利用Lyapunov有限时间稳定性理论和矩阵理论,给出了这类算法使得系统能够在有限时间内达到一致的充分条件,进而给出了一个满足条件的有限时间一致性算法,并对该算法的收敛性进行分析,得到了系统的收敛时间.数值仿真验证了所提出算法的有效性.     

Bipartite output consensus in networked multi-agent systems of high-order power integrators with signed digraph and input noises

In this paper, we concentrate on investigating bipartite output consensus in networked multi-agent systems of high-order power integrators. Systems with power integrator are ubiquitous among weakly coupled, unstable and underactuated mechanical systems. In the presence of input noises, an adaptive disturbance compensator and a technique of adding power integrator are introduced to the complex nonlinear multi-agent systems to reduce the deterioration of system performance. Additionally, due to the existence of negative communication weights among agents, whether bipartite output consensus of high-order power integrators can be achieved remains unknown. Therefore, it is of great importance to study this issue. The underlying idea of designing the distributed controller is to combine the output information of each agent itself and its neighbours, the state feedback within its internal system and input adaptive noise compensator all together. When the signed digraph is structurally balanced, bipartite output consensus can be reached. Finally, numerical simulations are provided to verify the validity of the developed criteria.     

输入饱和约束下多智能体的有限时间一致

为解决多智能体系统在有限时间跟踪控制过程中受输入饱和影响的问题,本文研究了输入饱和约束下的二阶线性多智能体系统的有限时间一致和跟踪控制.首先在无向通信拓扑下,利用齐次函数,设计了基于单饱和函数的有限时间一致和跟踪控制器.然后,应用李雅普诺夫稳定性理论和代数图论等方法证明了控制算法的稳定性.最后,给出了能够使多智能体系统实现有限时间一致和跟踪的充分条件.仿真结果验证了当系统存在输入饱和约束时,控制器能使多智能体在有限时间内完成跟踪任务.     

一类异构多智能体系统一致性协议的收敛性分析

针对一阶二阶智能体组成的异构多智能体系统,采用了一种线性一致性协议,基于图论和矩阵分析的方法对一致性协议的收敛性进行研究,得出了一致性协议最终收敛值的表达式,并给出了收敛区间,通过参数优化设置可以实现系统收敛到该区间内任意给定的期望值.最后在仿真实例中,实现了异构多机器人系统在期望位置的聚集,仿真结果验证了理论分析的正确性.     

A novel group consensus protocol for heterogeneous multi-agent systems

In this paper, we consider the group consensus problem of heterogeneous multi-agent systems. Based on the feature of heterogeneous agents, a novel protocol is proposed for heterogeneous multi-agent systems. First, the state transformation method is used and an equivalent system is obtained. Then, the group consensus problem is analysed and some sufficient and/or necessary conditions are given for heterogenous multi-agent systems under undirected and directed networks, respectively. Finally, simulation examples are presented to demonstrate the effectiveness of the theoretical results.     

Interval consensus problem of multi-agent systems in accordance with switching protocol

In this paper, we discuss the interval consensus problem of multi-agent systems by providing a special Laplacian of directed graphs. As one of the most important issues in the coordination control of multi-agent systems, the consensus problem requires that the output of several spatially distributed agents reach a common value that depends on the states of all agents. For the given consensus protocol and initial states, a fixed consensus value is obtained. The resulting consensus value, however, may not be ideal or meet the quality that we require from the multi-agent system. In this paper, by introducing two state-dependent switching parameters into the consensus protocol, the system given by the proposed protocol can globally asymptotically converge to a designated point on a special closed and bounded interval. In other words, the system given by the proposed protocol can globally asymptotically reach interval consensus and then the system can also achieve a generalised interval average consensus if the directed graph is balanced. Simulations are presented to demonstrate the effectiveness of our theoretical results.