Admissible Consensus of Multi‐Agent Singular Systems

Consensus problems are studied for both continuous‐time and discrete‐time multi‐agent singular systems with time‐invariant and directed communication topologies. Under restricted system equivalence of singular agents, sufficient and necessary conditions are obtained for admissible consensus ability with static protocols, which are based on both the relative information of the dynamic states and the absolute information of the static states. For a network of continuous‐time singular systems, the existence of admissible consensualization can be cast into strong stabilizability of the agent dynamics. Once discrete‐time multi‐agent singular systems satisfy the condition of reaching nontrivial final consensus states, strong stabilizability is a sufficient condition to achieve admissible consensualization. Two algorithms are proposed to construct two protocols, which are based on a linear matrix inequality and a modified Riccati equation, respectively. Finally, the algorithms are illustrated by two simulation examples.     

Synchronization of nonlinear heterogeneous cooperative systems using input–output feedback linearization

In this paper, input–output feedback linearization is used to design distributed controls for multi-agent systems with nonlinear and heterogeneous non-identical dynamics. Using feedback linearization, the nonlinear and heterogeneous dynamics of agents are transformed to identical linear dynamics and non-identical internal dynamics. Based on the dependence of agent outputs on agent inputs, feedback linearization may lead to a first-order or high-order tracking synchronization problem. The controller for each agent is designed to be fully distributed such that each agent only requires its own information and the information of its neighbors. The effectiveness of the proposed control protocols are verified by simulation on a microgrid test system.     

Adaptive position and orientation regulation for the camera‐in‐hand problem

This paper considers the camera‐space position and orientation regulation problem for the camera‐in‐hand problem via visual serving in the presence of parametric uncertainty associated with the robot dynamics and the camera system. Specifically, an adaptive robot controller is developed that forces the end‐effector of a robot manipulator to move such that the position and orientation of an object are regulated to a desired position and orientation in the camera‐space, despite parametric uncertainty throughout the entire robot‐camera system. An extension is also provided that illustrates how slight modifications can be made to the camera‐in‐hand control law to achieve adaptive position and orientation tracking of the end‐effector in the camera‐space for a fixed‐camera configuration. Simulation results are provided to illustrate the performance of the adaptive, camera‐in‐hand controller. © 2005 Wiley Periodicals, Inc.     

Intelligent modeling with agent‐based fuzzy cognitive map

This article presents an agent‐based fuzzy cognitive map (ABFCM) developed injecting the concept of multi‐agent system (MAS) into the fuzzy cognitive map (FCM). Fuzzy cognitive map is used for qualitative modeling and simulation. Compared to the FCM, the ABFCM enables different inference algorithms in each node enabling simulation of systems with diverse behavior concepts. Each map node can exhibit individual, more or less intelligent, behavior and still can interact with other nodes to conclude on system behavior. Resulting method also enables automatic results interpretation adding additional intelligence to a classic FCM. Explanation of the obtained system architecture with FCM and MAS integration is presented in the article. The experimental results in the article are obtained with the ABFCM prototype, developed on the basis of ABFCM structure given in the article. Multi‐agent technology can bring new properties into existing fields and methods, like in the ABFCM case. © 2010 Wiley Periodicals, Inc.     

Consensus and disturbance attenuation in multi‐agent chains with nonlinear control and time delays

In this paper, we investigate consensus and disturbance attenuation in a chain of mobile agents, which include non‐autonomous agents, semi‐autonomous agents and autonomous agents. In particular, the nonlinear dynamics of non‐autonomous agents is given and cannot be designed, while the dynamics of semi‐autonomous and autonomous agents can be partially and fully designed, respectively. To improve the robustness of multi‐agent chains against disturbances, we propose a nonlinear control framework for semi‐autonomous and autonomous agents such that they mimic the behavior of non‐autonomous agents for compatibility while also exploiting long‐range connections with distant agents. This framework ensures the existence of a unique consensus equilibrium, which is independent of the network size, connectivity topologies, control gains and information delays. Robustness of multi‐agent chains against disturbances is investigated by evaluating the frequency response at the nonlinear level. For infinitely long multi‐agent chains with recurrent patterns, we also derive a condition that ensures the disturbance attenuation but only requires the analysis of the linearized model. A case study is conducted for a connected vehicle system where numerical simulations are used to validate the analytical results. Copyright © 2016 John Wiley & Sons, Ltd.     

Agent-oriented modeling of the dynamics of biological organisms

In this paper, the agent-oriented modeling perspective to cope with biological complexity is discussed. Three levels of dynamics can distinguished and related to each other: dynamics of externally observable agent behavior, dynamics of internal agent processes, and dynamics of multi-agent organisations. This paper addresses the first two. Basic agent concepts to describe externally observable agent behavior are introduced. In the context of two case studies on animal behavior and cell functioning, it is shown how these concepts can be used to specify dynamic properties. In addition, a number of basic agent concepts to describe an agent’s internal processes are introduced. Also, these concepts are illustrated for specification of dynamic properties in the two case studies. Furthermore, the relationships between dynamic properties of externally observable behavior and dynamic properties of internal agent processes are addressed and illustrated for the animal and cell case studies.     

Distributed edge event‐triggered consensus protocol of multi‐agent systems with communication buffer

This paper proposes a distributed edge event‐triggered (DEET) scheme of multi‐agent systems via a communication buffer to reduce unnecessary update of controllers induced by fast information transmission. This edge scheme avoids a synchronous phenomenon in node event‐triggered mechanism, in which the triggering of one agent activates information transmission of all edges linked with this agent. Hence, the node event‐triggered scheme leads to unnecessary update of control protocols while the DEET provides a new approach without constrains on synchronous phenomenon of edge information exchange. That is, the communication on each edge is independent with other edges. In addition, we investigate another case where edge information transmission is subject to quantization and a quantized edge event‐triggered control protocol is proposed. Note that such a quantized protocol guarantees asymptotical consensus instead of bounded consensus in most of the existing literature. Meanwhile, both DEET and quantized edge event‐triggered schemes have nontrivial properties of excluding Zeno behavior. Furthermore, an algorithm is provided to avoid continuous event detection; hence, the communication traffic of the whole network is reduced significantly. Copyright © 2016 John Wiley & Sons, Ltd.     

Developing multi‐agent systems with a FIPA‐compliant agent framework

To ease large‐scale realization of agent applications there is an urgent need for frameworks, methodologies and toolkits that support the effective development of agent systems. Moreover, since one of the main tasks for which agent systems were invented is the integration between heterogeneous software, independently developed agents should be able to interact successfully. In this paper, we present JADE (Java Agent Development Environment), a software framework to build agent systems for the management of networked information resources in compliance with the FIPA specifications for inter‐operable intelligent multi‐agent systems. The goal of JADE is to simplify development while ensuring standard compliance through a comprehensive set of system services and agents. JADE can then be considered to be an agent middle‐ware that implements an efficient agent platform and supports the development of multi‐agent systems. It deals with all the aspects that are not peculiar to agent internals and that are independent of the applications, such as message transport, encoding and parsing, or agent life‐cycle management. Copyright © 2001 John Wiley & Sons, Ltd.     

Robust containment of uncertain linear multi‐agent systems under adaptive protocols

In this paper, robust containment problem is investigated for a class of multi‐leader multi‐agent linear systems in the presence of time‐varying uncertainties. To achieve containment, a new kind of adaptive containment protocols are proposed for the multi‐agent systems. Specifically, the designed protocols consist of a continuous linear term and a discontinuous term. The linear term of the designed protocol is employed to achieve containment while the discontinuous term is utilized to eliminate the effect of uncertain dynamics on the achievement of containment. By using tools from non‐smooth analysis and algebraic graph theory, some efficient criteria for achieving robust containment in the closed‐loop multi‐agent systems are obtained and analyzed. One favorable property of the designed protocol is that containment in the closed‐loop multi‐agent systems can be achieved in a fully distributed fashion over any given connected and detail‐balanced communication graph without using any global information about the communication graph. The effectiveness of the analytical results is finally verified by performing numerical simulations. Copyright © 2016 John Wiley & Sons, Ltd.     

Event‐based distributed robust synchronization control for multiple Euler‐Lagrange systems without relative velocity measurements

This paper focuses on the event‐based distributed robust leaderless synchronization control for multiple Euler‐Lagrange systems with directed communication topology that contains a directed spanning tree. Update frequency of the system is reduced by taking advantages of the event‐triggered approach, which can help extend the service life of the controller. Robust control theory is employed to guarantee the synchronization stability of the networked Euler‐Lagrange systems when unmodeled dynamics occur. The cost on the distributed synchronization protocol design can be saved due to the relaxation of the requirement on relative velocity measurements. Furthermore, our results are more practical because unknown disturbance is taken into consideration. In addition, it can be rigorously analyzed that each agent can exclude the undesired Zeno behavior. Some simulation examples are provided in the end to demonstrate the effectiveness of the proposed event‐based distributed robust control algorithm.     

Holography: a behavior‐based profiler for malware analysis

Behavior‐based detection and signature‐based detection are two popular approaches to malware (malicious software) analysis. The security industry, such as the sector selling antivirus tools, has been using signature and heuristic‐based technologies for years. However, this approach has been proven to be inefficient in identifying unknown malware strains. On the other hand, the behavior‐based malware detection approach has a greater potential in identifying previously unknown instances of malicious software. The accuracy of this approach relies on techniques to profile and recognize accurate behavior models. Unfortunately, with the increasing complexity of malicious software and limitations of existing automatic tools, the current behavior‐based approach cannot discover many newer forms of malware either. In this paper, we implement ‘holography platform’, a behavior‐based profiler on top of a virtual machine emulator that intercepts the system processes and analyzes the CPU instructions, CPU registers, and memory. The captured information is stored in a relational database, and data mining techniques are used to extract information. We demonstrate the breadth of the ‘holography platform’ by conducting two experiments: a packed binary behavior analysis and a malvertising (malicious advertising) incident tracing. Both tasks are known to be very difficult to do efficiently using existing methods and tools. We demonstrate how the precise behavior information can be easily obtained using the ‘holography platform’ tool. With these two experiments, we show that the ‘holography platform’ can provide security researchers and automatic malware detection systems with an efficient malicious software behavior analysis solution. Copyright © 2011 John Wiley & Sons, Ltd.     

Adaptive consensus with a virtual leader of multiple agents governed by locally Lipschitz nonlinearity

This paper is concerned with the second‐order consensus problem of multi‐agent systems with a virtual leader, where all agents and the virtual leader share the same intrinsic dynamics with a locally Lipschitz condition. It is assumed that only a small fraction of agents in the group are informed about the position and velocity of the virtual leader. A connectivity‐preserving adaptive controller is proposed to ensure the consensus of multi‐agent systems, wherein no information about the nonlinear dynamics is needed. Moreover, it is proved that the consensus can be reached globally with the proposed control strategy if the degree of the nonlinear dynamics is smaller than some analytical value. Numerical simulations are further provided to illustrate the theoretical results. Copyright © 2012 John Wiley & Sons, Ltd.     

Output feedback quantized observer‐based synchronization of linear multi‐agent systems over jointly connected topologies

The synchronization problem of linear over‐actuated multi‐agent systems with unmeasurable states is studied in this paper, under both limited communication data rate and switching topology flows. A class of adaptive quantized observer‐based encoding–decoding schemes and a class of certainty equivalence principle‐based control protocols are proposed. By developing the graph‐based space decomposition technique and analyzing the closed‐loop quantized dynamic equations, it is shown that if the network topology flow is jointly connected, the communication channels are periodic active, and the agent dynamics is observable, and with the orthogonal system matrix, the proposed communication and control protocols can ensure the closed‐loop system to achieve synchronization exponentially fast with finite bits of information exchange per step. Copyright © 2015 John Wiley & Sons, Ltd.     

Consensus of multi‐agent systems with time‐varying topology: An event‐based dynamic feedback scheme

The event‐based control strategy is an effective methodology for reducing the controller update and communication over the network. In this paper, the event‐based consensus of multi‐agent systems with linear dynamics and time‐varying topology is studied. For each agent, a state‐dependent threshold with an exponentially decaying bound is presented to determine the event times, and a new event‐based dynamic feedback scheme is proposed. It is shown that the controller update for each agent is only dependent on its own event times, which reduces significantly the controller update or computation for each agent. Moreover, based on the event‐based dynamic feedback scheme and the event triggering function presented in this paper, the continuous communication among neighboring agents is avoided, and the Zeno‐behavior of the closed‐loop systems is excluded. A numerical example is given to illustrate the effectiveness of theoretical results. Copyright © 2016 John Wiley & Sons, Ltd.     

A New Observer‐Type Consensus Protocol for Linear Multi‐Agent Dynamical Systems

The consensus problem is investigated in this paper for a class of multi‐agent systems with general linear node dynamics and directed communication topologies. A new distributed observer‐type consensus protocol is designed based only on the relative output measurements of neighboring agents. Compared with existing observer‐type protocols, the one presented here does not require information about the relative states of the observers. Tools from small gain theory and matrix analysis, some sufficient conditions are obtained for achieving consensus in such multi‐agent systems where the underlying network topology contains a directed spanning tree. Finally, some numerical examples including an application in low‐Earth‐orbit satellite formation flying are provided to illustrate the theoretical results.     

Design and implementation of a multiagent stock trading system

Stock trading is one of the key items in an economy and estimating its behavior and taking the best decision in it are among the most challenging issues. Solutions based on intelligent agent systems are proposed to cope with those challenges. Agents in a multiagent system (MAS) can share a common goal or they can pursue their own interests. That nature of MASs exactly fits the requirements of a free market economy. Although existing studies include noteworthy proposals on agent‐based market simulation and researchers discuss theoretical design issues of agent‐based stock exchange systems, unfortunately only a very few of the studies consider exact development and implementation of multiagent stock trading systems within the software engineering perspective and guides to the software engineers for constructing such software systems starting from scratch. To fill this gap, in this paper, we discuss the development of a multiagent‐based stock trading system by taking into consideration software design according to a well‐defined agent oriented software engineering methodology and implementation with a widely‐used MAS software development framework. Each participant in the system is first designed as belief–desire–intention agents with their facts, goals, and plans, and then belief–desire–intention reasoning and behavioral structure of the designed agents are implemented. Lessons learned during design and development within the software engineering perspective and evaluation of the implemented multiagent stock exchange system are also reported. Copyright © 2011 John Wiley & Sons, Ltd.     

Distributed consensus of multi‐agent systems with general linear node dynamics and intermittent communications

Without assuming that the mobile agents can communicate with their neighbors all the time, the consensus problem of multi‐agent systems with general linear node dynamics and a fixed directed topology is investigated. To achieve consensus, a new class of distributed protocols designed based only on the intermittent relative information are presented. By using tools from matrix analysis and switching systems theory, it is theoretically shown that the consensus in multi‐agent systems with a periodic intermittent communication and directed topology containing a spanning tree can be cast into the stability of a set of low‐dimensional switching systems. It is proved that there exists a protocol guaranteeing consensus if each agent is stabilizable and the communication rate is larger than a threshold value. Furthermore, a multi‐step intermittent consensus protocol design procedure is provided. The consensus algorithm is then extended to solve the formation control problem of linear multi‐agent systems with intermittent communication constraints as well as the consensus tracking problem with switching directed topologies. Finally, some numerical simulations are provided to verify the effectiveness of the theoretical results. Copyright © 2013 John Wiley & Sons, Ltd.     

多智能体系统在分布式采样控制下的动力学行为

本文运用图论、矩阵分析和现代控制理论等工具, 研究信息网络传输下多智能体系统的协调控制和动力学行为. 假设每个智能体通过数字化网络传感器获得其邻近智能体的位置状态,而且多智能体系统采取分布式线性控制协议. 每个智能体被描述为一个简单的采样系统,多智能体系统转化为混合动力学系统. 研究结果表明,多智能体系统所呈现的渐近聚集、周期振荡和发散动力学行为不仅和网络结构的代数特征有关, 而且和每个智能体的动力学方程、采样周期有关. 本文给出了具体精确的代数判据. 仿真例子进一步验证了本文结果的有效性.     

Output feedback control of a class of nonminimum‐phase nonlinear systems

The problem of global stabilization by output feedback is investigated in this paper for a class of nonminimum‐phase nonlinear systems. The system under consideration has a cascade configuration that consists of a driven system known as the inverse dynamics and a driving system. It is proved that although the zero dynamics may be unstable, there is an output feedback controller, globally stabilizing the nonminimum‐phase system if both driven and driving systems have a lower‐triangular form and satisfy a Lipschitz‐like condition, and the inverse dynamics satisfy a stronger version of input‐to‐state stabilizability condition. A design procedure is provided for the construction of an n‐dimensional dynamic output feedback compensator. Examples and simulations are also given to validate the effectiveness of the proposed output feedback controller. Copyright © 2016 John Wiley & Sons, Ltd.