多智能体系统的有限时间旋转环绕控制

本文主要研究了多智能体系统的分布式有限时间旋转环绕控制问题，其中每个智能体跟踪一个目标且每个目标被一个智能体跟踪.首先，设计了有限时间环绕跟踪协议，该协议包含对所有目标几何中心的观测器以及目标与其几何中心最大距离的估计器.其次，给出了闭环系统实现有限时间环绕跟踪的充分条件.最后，通过仿真验证了所得结果的有效性.     

单向通信拓扑领航者动态未知线性多智能体系统的协同迭代学习控制

研究单向通信拓扑领航者动态未知线性多智能体系统的协同跟踪问题.基于邻居的相对状态信息,设计了分布式迭代学习控制律实现对领航者的协同跟踪控制,采用Lyapunov-Krasovskii函数分析闭环系统的稳定性与收敛性.进而,将状态反馈结论拓展到输出反馈,通过构造局部观测器估计不可量测的状态信息,采用估计的相对状态信息设计了分布式迭代学习控制器.对于以上两种情形,多智能体系统在通讯拓扑含有生成树的条件下能够实现与领航者的状态同步,同时,所设计的分布式迭代学习律能够对领航者未知输入进行精确估计.仿真实例验证了所提方法的有效性.     

随机多智能体系统的有限时间多目标环绕控制

针对随机多智能体系统,研究了其多目标有限时间环绕控制问题,其中每个智能体可以跟踪多个目标,但是每个目标只能被一个智能体跟踪.首先,为每个智能体设计了目标状态的估计器,证明了在白噪声干扰之下每个智能体都可以在有限时间内对目标的几何中心位置作出估计.其次,为每个智能体设计了环绕半径的估计器,以及分布式环绕控制器.然后,利用李雅普诺夫有限时间随机稳定性理论,证明了所有智能体在有限时间内能够对环绕半径作出估计,同时可以实现有限时间环绕控制.最后,通过仿真验证了结果的有效性和正确性.     

基于位置信息的混合多智能体蜂拥控制方法

目前,很多蜂拥控制算法都是基于智能体通信半径为一个固定的值且既考虑多智能体之间的相对位置,又考虑它们的相对速度来设计的,然而,实际的情况往往不会有那么理想。文中试图在基于通信半径不同的混合多智能体控制策略的设计过程中减少考虑的控制因素的个数（只考虑位置信息）,提出一种分布式的控制算法。此控制算法能实现多智能体跟随一个速度固定的虚拟领航者,形成聚合、无碰撞的队列。给出了算法的可行性理论分析,并针对20个智能体跟踪一个速度固定的虚拟领导者的情形给出了计算机仿真,用以验证算法的可行性。     

基于位置信息的混合多智能体蜂拥控制方法

目前,很多蜂拥控制算法都是基于智能体通信半径为一个固定的值且既考虑多智能体之间的相对位置,又考虑它们的相对速度来设计的,然而,实际的情况往往不会有那么理想。文中试图在基于通信半径不同的混合多智能体控制策略的设计过程中减少考虑的控制因素的个数（只考虑位置信息）,提出一种分布式的控制算法。此控制算法能实现多智能体跟随一个速度固定的虚拟领航者,形成聚合、无碰撞的队列。给出了算法的可行性理论分析,并针对20个智能体跟踪一个速度固定的虚拟领导者的情形给出了计算机仿真,用以验证算法的可行性。     

非完整约束多智能体系统基于屏障控制函数的分布式协同控制

本文设计了一种基于屏障控制函数(CBF)的分布式协同控制算法,实现了领航–跟随者框架下非完整约束多智能体系统的连通性与编队控制.首先,通过将连通性保持问题建模为系统约束,定义了该约束的调零屏障函数(ZBF).其次,在此基础上,构建李雅普诺夫函数与角速度输入之间的关系,对跟随者智能体设计了基于调零屏障函数的协同控制算法,其中线速度控制器保证跟随者的速度的跟踪与队形的跟踪,而梯度型角速度控制器实现跟随者角度的矫正.然后,利用调零屏障函数不变集相关引理证明了连通性约束集为正不变集,若初始时刻连通,则跟随者智能体始终与领航者保持连通性.同时,本文提出的算法实现编队误差的渐近收敛.本文中的队形适用常见的固定队形编队需求,也适用于领航者是动态(有线速度和角速度)的情况.最后,通过数值仿真进一步验证了该算法在不同队形需求下的有效性.     

有向图中网络Euler-Lagrange系统的自适应协调跟踪

基于一致性理论, 在有向图中研究网络 Euler-Lagrange 系统的协调跟踪控制. 所有跟随智能体的动力学模型均为 Euler-Lagrange 方程. 在仅有部分跟随智能体能获取领航智能体信息的情形下, 同时考虑系统模型的参数不确定性, 设计分布式自适应控制律实现所有跟随智能体对领航智能体的跟踪. 针对领航智能体的运动状态, 考虑以下两种情形: 1) 领航智能体为固定点; 2) 领航智能体为动态点. 对第一种情形, 设计的控制律使得所有跟随智能体渐近交会于固定点; 对第二种情形, 首先对每个跟随智能体设计分布式连续估计器, 然后提出了分布式自适应控制律. 当每个跟随智能体均能获取领航智能体的加速度信息时, 设计的控制律能实现对领航智能体的渐近跟踪, 当跟随智能体不能获取领航智能体的加速度信息时, 跟踪误差是有界的. 最后通过仿真分析验证设计的控制算法是合理有效的.     

有领航者的多智能体系统的稳定性分析

本文研究了一类有领航者的多智能体系统在平面和高斯型源下的稳定性分析.该系统由领航者和跟随者两种智能体组成,只有领航者具有环境的信息;同时,吸引与排斥函数也被推广到具有某些性质的一类函数.证明了在满足适当假设条件时,在领航者智能体的导航作用下,多智能体系统的跟随者在没有环境信息的情况下也能准确地到达目标或远离目标.当多智能体系统在不同源的条件下聚集时有界区域的大小也被估计.给出数值仿真以证明理论结果的正确性.     

利用方位角信息的移动机器人编队控制

本文以移动机器人为研究对象,仅利用方位角信息实现多智能体系统的编队控制.为实现大规模编队和队形的缩放控制,智能体被分为领航者、第1跟随者以及其余跟随者.首先,考虑智能体之间相对位置信息难以精确测量的情形,设计仅用方位角信息的估计算法获得准确的相对位置;然后,基于获得的相对位置信息设计第1跟随者的控制算法,使得第一跟随者与领航者之间的位置收敛到理想约束位置以控制整个队形的规模;接着,设计其余跟随者的控制算法使得各智能体之间的方位角达到理想约束角度,从而形成理想编队队形.最后通过数值和ROS仿真实验验证算法的有效性.     

分数阶多机器人的领航–跟随型环形编队控制

针对多机器人系统的环形编队控制复杂问题,提出一种基于分数阶多机器人的环形编队控制方法,应用领航–跟随编队方法来控制多机器人系统的环形编队和目标包围,通过设计状态估测器,实现对多机器人的状态估计.由领航者获取系统中目标状态的信息,跟随者监测到领航者的状态信息并完成包围环绕编队控制,使多机器人系统形成对动态目标的目标跟踪.根据李雅普诺夫稳定性理论和米塔格定理,得到多机器人系统环形编队控制的充分条件,实现对多机器人系统对目标物的包围控制,通过对一组多机器人队列的目标包围仿真,验证了该方法的有效性.     

Distributed robust consensus control of multi-agent systems with heterogeneous matching uncertainties

This paper considers the distributed consensus problem of linear multi-agent systems subject to different matching uncertainties for both the cases without and with a leader of bounded unknown control input. Due to the existence of nonidentical uncertainties, the multi-agent systems discussed in this paper are essentially heterogeneous. For the case where the communication graph is undirected and connected, based on the local state information of neighboring agents, a fully distributed continuous adaptive consensus protocol is designed, under which the consensus error is uniformly ultimately bounded and exponentially converges to a small adjustable bounded set. For the case where there exists a leader whose control input is unknown and bounded, a distributed adaptive consensus protocol is proposed to ensure the boundedness of the consensus error. A sufficient condition for the existence of the proposed protocols is that each agent is stabilizable.     

Distributed Time-Varying Formation Tracking Analysis and Design for Second-Order Multi-Agent Systems

Distributed time-varying formation tracking analysis and design problems for second-order multi-agent systems with one leader are studied respectively, where the states of followers form a predefined time-varying formation while tracking the state of the leader. Different from the previous results on formation tracking control, the formation for the followers can be described by specified time-varying vectors and the trajectory of the leader can also be time-varying. A distributed formation tracking protocol is constructed using only neighboring relative information. Necessary and sufficient conditions for second-order multi-agent systems with one leader to achieve time-varying formation tracking are proposed by utilizing the properties of the Laplacian matrix, where the formation tracking feasibility constraint is also given. An approach to design the formation tracking protocol is proposed by solving an algebraic Riccati equation. The presented results can be applied to deal with the target enclosing problems and consensus tracking problems for second-order multi-agent systems with one target/leader. An application in the target enclosing of multiple vehicles is provided to demonstrate the effectiveness of the theoretical results.     

A Novel Leader-following Consensus of Multi-agent Systems with Smart Leader

This article studies the leader-following consensus problem for mixed-order multi-agent systems with a leader. Different from the traditional leader which is independent of all the other agents, the leader, called smart leader, can obtain and utilize the feedback information from its neighbors at some disconnected time intervals. A new distributed consensus control protocol based on intermittent control is developed for leader-following consensus with a smart leader. Moreover, the smart leader can adjust the control protocol based on the feedback information from its neighbors. With the aid of Lyapunov function, some sufficient conditions are derived for leader-following consensus of multi-agent systems with mixed-order dynamics under fixed directed topology. In addition, the similar results are obtained under switching directed topology. Finally, simulation results are provided to verify the correctness and effectiveness of theoretical results.     

Iterative Consensus for a Class of Second-order Multi-agent Systems

In this paper, the problem of leader-following consensus for a class of multi-agent systems with double integrator dynamics is investigated based on an iterative learning approach. Consensus errors of individual agents are considered as the anticipation in time, based on which a distributed iterative learning protocol is proposed for the undirected networks with fixed topology to make the followers track the leader in finite time. The dynamic of the leader is assumed to be time-varying and the state information is available to only a portion of the followers. The sufficient condition for solving the consensus problem of the multi-agent system is obtained. A simulation example is provided to demonstrate the effectiveness of the proposed method.     

Finite-time consensus of time-varying nonlinear multi-agent systems

This paper investigates the problem of leader–follower finite-time consensus for a class of time-varying nonlinear multi-agent systems. The dynamics of each agent is assumed to be represented by a strict feedback nonlinear system, where nonlinearities satisfy Lipschitz growth conditions with time-varying gains. The main design procedure is outlined as follows. First, it is shown that the leader–follower consensus problem is equivalent to a conventional control problem of multi-variable high-dimension systems. Second, by introducing a state transformation, the control problem is converted into the construction problem of two dynamic equations. Third, based on the Lyapunov stability theorem, the global finite-time stability of the closed-loop control system is proved, and the finite-time consensus of the concerned multi-agent systems is thus guaranteed. An example is given to verify the effectiveness of the proposed consensus protocol algorithm.     

Leader-following Consensus of Multi-agent Systems via a Hybrid Protocol with Saturation Effects

In this paper, a hybrid protocol which can control multi-agent systems to achieve “leader-following consensus” is proposed, the control protocol is periodic and is composed of continuous control and impulse control. Considering the power limitation and the time error of the actual industrial production equipments, the impulse saturation effects and the impulse time window are introduced. In this paper, the multi-agent system is modeled, one of the agents is designated as the leader, and the rest of the agents are the followers. Then the error system equations of the multi-agent system is derived. The stability of the error system is analyzed by constructing the Lyapunov function. Theorem 1 and theorem 2 are obtained as the criteria of state consensus of the multi-agent system. Finally, a numerical experiment is carried out to verify the reliability and efficiency of the conclusions are given in this paper. Because it takes into account the impulse time window and impulse saturation effects, which is more in line with the actual industrial production.

     

Controllability of heterogeneous multi-agent systems under directed and weighted topology

This paper considers the controllability problem for both continuous- and discrete-time linear heterogeneous multi-agent systems with directed and weighted communication topology. First, two kinds of neighbour-based control protocols based on the distributed protocol of first-order and second-order multi-agent systems are proposed, under which it is shown that a heterogeneous multi-agent system is controllable if the underlying communication topology is controllable. Then, under special leader selection, the result shows that the controllability of a heterogeneous multi-agent system is solely decided by its communication topology graph. Furthermore, some necessary and/or sufficient conditions are derived for controllability of communication topology from algebraic and graphical perspectives. Finally, simulation examples are presented to demonstrate the effectiveness of the theoretical results.     

Second-order tracking control for leader-follower multi-agent flocking in directed graphs with switching topology

This paper investigates the flocking problem for leader-follower multi-agent systems in directed graphs with switching topology. A decentralized state control rule, namely, a second-order protocol, is designed for each agent to track the leader. And it is proved that the proposed control scheme can effectively estimate the tracking error of each agent when the leader is active. Particularly, to ensure the tracking error can be estimated, the following two questions are solved: (1) How many agents are needed to connect to the leader? (2) How should these connections be distributed? Finally, a simple example is also given to verify the effectiveness of the proposed theorems.     

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.      

Distributed tracking control of leader-follower multi-agent systems under noisy measurement

In this paper, a distributed tracking control scheme with distributed estimators has been developed for a leader-follower multi-agent system with measurement noises and directed interconnection topology. It is supposed that each follower can only measure the relative positions of its neighbors in a noisy environment, including the relative position of the second-order active leader. A neighbor-based tracking protocol together with distributed estimators is designed based on a novel velocity decomposition technique. It is shown that the closed loop tracking control system is stochastically stable in mean square and the estimation errors converge to zero in mean square as well. A simulation example is finally given to illustrate the performance of the proposed control scheme.