二阶非线性多智能体系统领导跟随一致性研究

为减少通信时延对系统一致性的影响,针对有领导者的二阶非线性多智能体系统的领导跟随一致性进行了研究,新颖的提出近似随机脉冲时延的概念并应用于新协议。相比于传统协议,新协议在脉冲时刻通信时延较小时,各智能体基于时延态对自身当前时刻状态进行预测,并以自身未来预测状态取代时延态发送给各邻接智能体同时补偿自身反馈通道时延,从而使系统更快实现一致性。基于Lyapunov稳定性理论,利用一类再推广的Halanay不等式的性质给出两个保证系统实现一致性的充分条件。最后,实例仿真证明了新协议的优越性。     

具有领航者的时延多智能体系统的群集运动

计算机技术、网络技术和通信技术的飞速发展,推动着无人驾驶飞行器的编队控制、传感器网络的分布控制、卫星的姿态控制等多智能体系统的建模与应用的逐步深入,也吸引了越来越多的研究者致力于多智能体系统的动态编队控制的研究.研究了具有不同的通信时延和不同的输入时延的移动多智能体算法的群集运动.假设多智能体系统由n个智能体和1个Leader组成,网络连接拓扑是静态有向连通图,智能体Leader为拓扑图的全局可达节点.应用频率域的广义Nyquist判据分析了具有不同的通信时延和不同的输入时延的移动多智能体算法,应用Greshgorin圆盘定理和曲线的曲率理论研究了具有领航者的多智能体算法的群集运动,得到保证系统一致性的收敛条件.该一致性条件是一个应用节点局部信息的分散式条件,只与输入时延有关,而与通信时延无关.最后,通过计算机仿真验证了本文结论的有效性.     

具有随机时延的的多智能体系统的一致性

本文研究了具有随机时不变通信时延的多智能体系统的一致性问题。假设系统拓扑是固定有向的强连通图,考虑多智能体系统中存在随机通信时延的情况,即各智能体之间的通信时延是以一定概率存在的,采用具有动态参考状态的一致性控制算法,通过变量代换,将多智能体的一致性问题转化为误差系统的渐进稳定性问题,然后再应用Lyapunov稳定性理论与随机分析方法推导出误差系统在该算法作用下趋于稳定的充分条件,并以线性矩阵不等式（LMIs）表示,即原多智能体系统在此充分条件下各智能体的状态能够达到一致。最后应用一个实例验证了所提出结论的有效性。     

具有定常输入的二阶多智能体系统的平均一致性滤波

本文考察了具有定常输入的二阶多智能体系统平均一致性滤波问题,提出了一种比例-积分一致性滤波算法。在定常输入和固定对称连通拓扑的前提下,根据Routh判据和Nyquist判据分别得到二阶多智能体系统在无时延和相同通信时延约束下渐近收敛一致的收敛条件,且多智能体系统最终一致性状态为定常输入的平均值。最后,通过由5个智能体组成的多智能体系统在连通拓扑结构下的数值仿真,验证了理论结果的正确性。     

一类多时变时延异质多智能体系统的组一致性

研究了一类由一阶和二阶智能体组成的异质多智能体系统的组一致性问题．首先,在多时变时延异质系统中设计了实现静态组一致的控制算法;其次,运用稳定性理论和线性矩阵不等式,分别给出了无时延、同时具有通信与输入时延的异质多智能体系统实现组一致性的充分条件;再次,通过求解一组可行的线性矩阵不等式,得到了输入时延的容许上界,并得出了通信时延与异质多智能体系统的组一致性无关的结论;最后,仿真结果验证了理论结果的有效性．     

含时延约束的多智能体系统二分一致性

针对多智能体系统中信息交互存在通信时延这一约束,在无向符号图拓扑结构下分别研究了含固定时延和时变时延的一阶多智能体系统二分一致性问题。通过设计相应的控制协议,使得该系统收敛到两个模值相同但符号不同的状态。在稳定性分析中,利用广义Nyquist准则的方法,得到含固定时延多智能体系统实现二分一致性的充分条件;对含时变时延系统构造包含三重积分项的Lyapunov函数,利用积分不等式和线性矩阵不等式理论,并结合自由矩阵的方法得到含时变时延多智能体系统实现二分一致性的充分条件。最后,数值仿真验证了所得结论的有效性和正确性。     

基于观测器的线性时变时滞多智能体系统一致性

针对系统状态不可测和具有通信时延的线性多智能体系统,提出一种基于观测器的一致性控制算法.设计观测器用于解决智能体状态不可测的问题,在观测器的基础上,提出一种控制协议来实现带时变时延的线性多智能体系统一致性.利用模型转换的方式将原系统转换为新的模型系统,在此基础上,构造Lyapunov-Krasovskii函数并分析系统稳定性,通过求解线性矩阵不等式获取控制器系数矩阵.最后通过Matlab数值仿真验证所提出方法的有效性.     

离散时间系统的多智能体的一致性

动态多智能体系统的一致性是复杂动力学系统中很有现实意义的问题.假设智能体连接网络拓扑是无向,固定和连通的,而且个体之间信息传递存在通信时延,分析了一个动态移动多智能体离散时间系统.应用广义Nyquist判据研究具有通信时延的多智能体离散时间系统,得到了保证系统达到一致的充分条件.最后应用计算机仿真验证了该结论的有效性.

     

对抗网络下时滞非线性多智能体系统固定时间二分一致性

本文针对一类存在输入时延的非线性多智能体系统,研究了其在结构平衡的无向符号图下的固定时间二分一致性问题.首先,本文针对智能体间相互合作与相互竞争的关系,设计了一类存在输入时延的多智能体系统固定时间分布式一致性控制协议,使得系统状态在固定时间内收敛到数值相同但符号相反的两个值,且收敛时间上界与初始状态无关.随后,利用Lyapunov稳定性理论和代数图论给出了在存在输入时延的情况下多智能体系统实现固定时间二分一致性的充分条件和收敛时间的上界值,证明了控制算法的稳定性.最后,仿真实例验证了所提固定时间二分一致性算法和理论结果的有效性.     

具有随机通信时延的二阶多智能体系统的一致性控制

研究了具有随机通信时延的二阶多智能体系统的一致性控制问题.分别讨论了具有固定拓扑结构和变化拓扑结构两种情形下二阶多智能体系统在具有随机通信时延情况下的一致性问题.通过构造Lyapunov函数的方法得到多智能体系统的时延依赖稳定判据,并以线性矩阵不等式(LMI)的形式给出了系统稳定的条件.最后,仿真和实验结果验证了研究所得结论的正确性和有效性.     

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.     

Group consensus of multi-agent systems in directed networks with noises and time delays

In this paper, group consensus problems in fixed directed networks of dynamic agents are investigated. Group consensus means that the agents in each group share a consistent value while there is no agreement between any two groups. Based on algebraic graph theory, sufficient conditions guaranteeing group consensus under the proposed control protocol in the presence of random noises and communication delays are derived. The analysis uses a stability result of Mao for stochastic differential delay equations, which ensures the consensus can be achieved almost surely and exponentially fast. Numerical examples are provided to demonstrate the availability of the obtained results as well as the effect of time delay/noise intensity.     

Distributed adaptive consensus for multiple mechanical systems with switching topologies and time-varying delay

This paper studies the adaptive consensus problem of networked mechanical systems with time-varying delay and jointly-connected topologies. Two different consensus protocols are proposed. First, we present an adaptive consensus protocol for the connected switching topologies. Based on graph theory, Lyapunov stability theory and switching control theory, the stability of the proposed algorithm is demonstrated. Then we investigate the problem under the more general jointly-connected topologies, and with concurrent time-varying communication delay. The proposed consensus protocol consists of two parts: one is for the connected agents which contains the current states disagreement among them and the other is designed for the isolated agents which contains the states difference between the current and past. A distinctive feature of this work is to address the consensus control problem of mechanical systems with unknown parameters, time-varying delay and switching topologies in a unified theoretical framework. Numerical simulation is provided to demonstrate the effectiveness of the obtained results.     

Distributed consensus of delayed multi‐agent systems with nonlinear dynamics via intermittent control

In this paper, a distributed consensus of delayed multi‐agent systems with a leader is investigated, and a nonlinear protocol is proposed based on intermittent control. A notable feature of this protocol is to address second‐order consensus problems for delayed nonlinear multi‐agent systems, where agents can only communicate with each other over some disconnected time intervals. Some sufficient conditions to guarantee the consensus over fixed and switching topologies are derived. It is shown that second‐order consensus for delayed multi‐agent system with intermittent control can be achieved if the time delay is less than a critical value and the communication time duration is larger than a threshold value. In addition, some numerical examples are given to illustrate the effectiveness and feasibility of the theoretical results.     

Round-Robin协议下基于观测器的多智能体系统H∞一致性控制

针对一类具有非线性动态特性的多智能体系统,研究Round-Robin(RR)通信协议下基于观测器的H_∞一致性控制问题。在智能体与其邻居智能体之间的通信信道引入了Round-Robin通信协议,缓解信道拥堵带来的测量丢失、时延等问题。通过RR协议的调度,使得智能体在每一时刻确保能够接收到一个邻居智能体信息。首先,根据智能体的测量输出设计状态观测器,对每个智能体的状态进行估计,然后,根据估计状态设计一致性控制器,基于李雅普诺夫稳定性理论,给出多智能体系统满足H_∞一致性性能指标的充分条件,进而通过求解线性矩阵不等式(LMI)获得观测器及控制器参数。最后,将本文设计的控制算法应用于数值仿真和柔性连杆机器人的一致性控制,验证所设计算法的可行性和有效性。     

\begin{document}$H_\infty$\end{document} Consensus Control of Discrete-Time Multi-Agent Systems Under Network Imperfections and External Disturbance

This paper presents a distributed control protocol for consensus control of multi-agent systems (MASs) under external disturbances and network imperfections, including communication delay and random packet dropout. To comply with the discrete nature of networked systems, in contrast to most of the existing work for MASs under network imperfections, the agents are modeled by discrete-time dynamics. The communication network is considered to be undirected, its delay is considered to be time-varying but bounded, and its packet dropout is modeled by a Bernoulli distributed white sequence. Sufficient conditions in terms of linear matrix inequalities (LMIs) for asymptotic mean-square consensus stability are derived under network imperfections without considering external disturbances. A desired disturbance attenuation level in the presence of both external disturbances and network imperfections is also provided. A simulation example is given to verify the effectiveness of the proposed approach in coping with network imperfection and disturbances.      

Weighted average prediction for improving consensus performance of second-order delayed multi-agent systems

In this paper, the weighted average prediction (WAP) is introduced into the existing consensus protocol for simultaneously improving the robustness to communication delay and the convergence speed of achieving the consensus. The frequency-domain analysis and algebra graph theory are employed to derive the necessary and sufficient condition guaranteeing the second-order delayed multi-agent systems applying the WAP-based consensus protocol to achieve the stationary consensus. It is proved that introducing the WAP with the proper length into the existing consensus protocol can improve the robustness against communication delay. Also, we prove that for two kinds of second-order delayed multi-agent systems: 1) the IR-ones with communication delay approaching zero and 2) the ones with communication delay approaching the maximum delay, introducing the WAP with the proper length into the existing consensus protocol can accelerate the convergence speed of achieving the stationary consensus.     

Solving a modified consensus problem of linear multi-agent systems

A distributed protocol is proposed for a modified consensus problem of a network of agents that have the same continuous-time linear dynamics. Each agent estimates its own state using its output information and then sends the estimated state to its neighbor agents for the purpose of reaching a consensus. The modified consensus problem requires the group decision value to be a linear function of initial states and initial estimated states of all agents in the network, and the transformation matrix associated with this linear function not to be a zero matrix. It is proved that under the proposed control protocol, the modified consensus problem can be solved if and only if the system matrices of the agent’s dynamics are stabilizable and detectable, the input matrix is not a zero matrix, and the communication topology graph has a spanning tree. The proposed protocol can also be extended to multi-agent systems where agents are described by discrete-time linear dynamics. The corresponding necessary and sufficient conditions are provided as well.     

Consensus of a class of second‐order nonlinear heterogeneous multi‐agent systems with uncertainty and communication delay

In this paper, a consensus problem is studied for a group of second‐order nonlinear heterogeneous agents with non‐uniform time delay in communication links and uncertainty in agent dynamics. We design a class of novel decentralized control protocols for the consensus problem whose solvability is converted into stability analysis of an associated closed‐loop system with uncertainty and time delay. Using an explicitly constructed Lyapunov functional, the stability conditions or the solvability conditions of the consensus problem are given in terms of a set of linear matrix inequalities apart from a small number of scalar parameters that appear nonlinearly. Furthermore, the linear matrix inequalities are theoretically verified to be solvable when the communication delay is sufficiently small. The effectiveness of the proposed control protocol is illustrated by numerical examples. Copyright © 2016 John Wiley & Sons, Ltd.