Networked Euler-Lagrange Systems Research Articles

Coordination Control of Networked Euler-Lagrange Systems with Possible Switching Topology

摘要: 研究切换网络拓扑下含未知参数的分布式Euler-Lagrange系统(简称EL系统)的自适应协调控制问题.通过引入一种新颖的自适应控制构架,设计了分散式控制器,使其容许未知的系统参数.基于图论,Lyapunov稳定性理论以及切换控制理论证明了算法的稳定性.本文特色在于在同一理论框架下处理EL系统协调控制中的未知参数问题与切换拓扑问题,实现静态和动态两种情况下的控制目标.仿真结果验证了算法的有效性. 关键词: Euler-Lagrange系统 / 协调控制 / 切换拓扑 / 自适应控制

Synchronization of Lagrangian Systems With Irregular Communication Delays

The synchronization problem of networked Euler-Lagrange systems with unknown parameters is addressed. The information flow in the network is represented by a directed communication graph and is subject to unknown and possibly discontinuous time-varying communication delays with unknown upper bounds. We propose a control scheme that achieves position synchronization, i.e., all the positions of the systems converge to a common final position, provided that the directed communication graph contains a spanning tree. The convergence analysis of the proposed scheme is based on the multidimensional small-gain framework. Simulation results on a network of ten robot manipulators are given to illustrate the effectiveness of the proposed control scheme.

Finite‐time cooperative‐tracking control for networked Euler–Lagrange systems

This study investigates the finite-time cooperative-tracking problem for a class of networked Euler-Lagrange systems with a leader-follower structure, where the leader has an active dynamics and only a subset of the followers have access to the leader system. A novel framework for the design of finite-time cooperative-tracking controller is proposed by using sliding-mode control theory and graph theory. First, a finite-time sliding-mode tracking protocol is proposed for the networked Lagrange systems in the presence of bounded model uncertainties and external disturbances. Under the condition that the bounds of the model uncertainties and external disturbances are unknown, adaptive finite-time cooperative-tracking protocol is then presented. The finite convergence time is also estimated. Finally, we analyse the tracking performance of the networked uncertain Lagrange systems under the action of a continuous control protocol, which guarantees that the tracking errors converge to an arbitrarily small bound around zero in finite time. Simulation examples are presented to show the effectiveness of the obtained theoretical results.

Coordination Control of Networked Euler-Lagrange Systems with Possible Switching Topology

This paper studies adaptive coordination control of Euler-Lagrange (EL) systems with unknown parameters in system dynamics and possible switching topology. By introducing a novel adaptive control architecture, decentralized controllers are developed, which allow for parametric uncertainties. Based upon graph theory, Lyapunov theory and switching control theory, the stability of the proposed algorithms are demonstrated. A distinctive feature of this work is to address the coordination control of EL systems with unknown parameters and switching topology in a unified theoretical framework. It is shown that both static and dynamic coordinations can be reached even when the communication is switching. Simulation results are provided to demonstrate the effectiveness of the obtained results.

Distributed robust control for synchronised tracking of networked Euler–Lagrange systems

In this paper, we propose a distributed robust control method for synchronised tracking of networked Euler–Lagrange systems, where the time-varying reference trajectory is sent to only a subset of the agents. It is assumed that the agents can exchange information with their local neighbours on a bidirectionally connected communication graph. In the local controller equipped in each generalised coordinate of the agents, a disturbance observer is introduced to compensate for the low-passed-coupled uncertainties, and a sliding mode control term is employed to handle the uncertainties that the disturbance observer cannot compensate for sufficiently. By some damping terms, the boundedness of the signals of the overall networked nonlinear systems is first ensured. Then we show how the disturbance observer and sliding mode control term play in a cooperative way in each local generalised coordinate to achieve an excellent synchronised tracking performance. Simulation results are provided to support the theoretical results.

Reconfigurable Synchronization Control of Networked Euler‐Lagrange Systems with Switching Communication Topologies

AbstractIn this paper, a methodology is proposed for the design of reconfigurable control of networked heterogeneous Euler‐Lagrange systems subject to actuator faults. It is assumed that the underlying communication network topology is switching. We consider two types of actuator faults, namely: (i) additive, and (ii) loss of effectiveness. By modifying the originally designed “nominal” control algorithm developed for state synchronization of the healthy system, two reconfigurable control algorithms are developed for ensuring state synchronization in the presence of faults. Extensions of these results to velocity synchronization of networked Euler‐Lagrange systems subject to two actuator faults are also provided. It is shown that state and velocity synchronization can be achieved for switchings among a family of connected communication topologies as well as for switchings among nominal controllers to reconfigured controllers and vice versa. Simulation results for a network of surface marine vehicles demonstrate the effectiveness and capabilities of our proposed reconfigurable control algorithms.

Distributed consensus algorithm for networked Euler-Lagrange systems with self-delays and uncertainties

Distributed consensus algorithm for networked Euler-Lagrange systems with self-delays and uncertainties

Distributed Adaptive Synchronization of Networked Euler-Lagrange Systems with Communication Delays

摘要: 对一类含未知参数的Euler-Lagrange系统协调控制问题进行了研究, 提出了一种自适应控制算法. 该算法容许通信网络为最一般的伪强连通图, 并允许通信时延的存在. 对系统中领航者为静态和动态两种情况分别进行了研究, 设计了相应的控制器.研究结果表明,在仅有部分个体能够和领航者进行通信的情况下, 控制器能保证网络中其他个体最终和领航者趋于一致. 运用Lyapunov稳定性定理和Barbalat 定理等对自适应控制器的稳定性进行了证明,并利用数值仿真验证了算法的有效性. 关键词: Euler-Lagrange系统 / 协调控制 / 通信时延 / 自适应控制

An Overview on Coordination Control Problem of Multi-agent System

摘要: 对多个体协调控制问题的研究现状进行综述. 介绍了多个体协调控制领域的基本问题, 并结合系统中网络与动力学不确定性, 对该领域当前的研究热点和前沿进行分析阐述. 进一步, 对工程中广为应用的Euler-Lagrange系统协调控制最新研究成果进行归纳总结. 最后指出该研究领域存在的问题及今后的研究方向. 关键词: 协调控制 / 一致性 / 时延 / 拓扑切换 / 异步网络 / 网络化Euler-Lagrange系统

Distributed Coordinated Tracking With a Dynamic Leader for Multiple Euler-Lagrange Systems

In this note, we study a distributed coordinated tracking problem for multiple networked Euler-Lagrange systems. The objective is for a team of followers modeled by full-actuated Euler-Lagrange equations to track a dynamic leader whose vector of generalized coordinates is time varying under the constraints that the leader is a neighbor of only a subset of the followers and the followers have only local interaction. We consider two cases: i) The leader has a constant vector of generalized coordinate derivatives, and ii) The leader has a varying vector of generalized coordinate derivatives. In the first case, we propose a distributed continuous estimator and an adaptive control law to account for parametric uncertainties. In the second case, we propose a model-independent sliding mode control algorithm. Simulation results on multiple networked two-link revolute joint arms are provided to show the effectiveness of the proposed control algorithms.

Distributed adaptive consensus algorithm for networked Euler–Lagrange systems

Most consensus protocols developed in the past are for linear-integrator systems or deterministic non-linear systems. Here, the authors study the state consensus for non-point, non-linear networked Euler-Lagrange systems with unknown parameters. Specifically, state consensus problems with both coupling time delay and switching topology are investigated. By establishing a unified architecture based on the passivity property, adaptive consensus protocols are developed. It is shown that state consensus is reachable despite the unknown parameters, and the estimation errors of these parameters converge to zero. Furthermore, by introducing the leader-follower architecture, the authors show that each agent will converge its origin. Finally, a numerical example is given to illustrate the effectiveness of the proposed algorithms.

State Synchronization of Networked Euler-Lagrange Systems with Switching Communication Topologies Subject to Actuator Faults

AbstractReconfigurable control of networked heterogeneous Euler-Lagrange (EL) systems subject to actuator faults is considered in this paper. It is assumed that the communication network is time-varying (switching). We first introduce a distributed control strategy for state synchronization of multiple EL systems. This controller is denoted as the “nominal” controller. To guarantee state synchronization of the switching communication network topologies we require existence of a non-vanishing dwell-time between any two sequential switches. Next, we consider two types of actuator faults namely (1) an additive actuator fault, and (2) a loss of effectiveness actuator fault. By employing the nominal control algorithm developed for state synchronization, we introduce two other control algorithms for state synchronization in presence of the faults. Simulation results illustrate and demonstrate the effectiveness of our proposed control algorithms.

Distributed leaderless consensus algorithms for networked Euler–Lagrange systems

This article proposes and analyses distributed, leaderless, model-independent consensus algorithms for networked Euler–Lagrange systems. We propose a fundamental consensus algorithm, a consensus algorithm accounting for actuator saturation, and a consensus algorithm accounting for unavailability of measurements of generalised coordinate derivatives, for systems modelled by Euler–Lagrange equations. Due to the fact that the closed-loop interconnected Euler–Lagrange equations using these algorithms are non-autonomous, Matrosov's theorem is used for convergence analysis. It is shown that consensus is reached on the generalised coordinates and their derivatives of the networked Euler–Lagrange systems as long as the undirected communication topology is connected. Simulation results show the effectiveness of the proposed algorithms.