Decentralized Estimation of Laplacian Eigenvalues in Multi-Agent Systems

In this paper we present a decentralized algorithm to estimate the eigenvalues of the Laplacian matrix that encodes the network topology of a multi-agent system. We consider network topologies modeled by undirected graphs. The basic idea is to provide a local interaction rule among agents so that their state trajectory is a linear combination of sinusoids oscillating only at frequencies function of the eigenvalues of the Laplacian matrix. In this way, the problem of decentralized estimation of the eigenvalues is mapped into a standard signal processing problem in which the unknowns are the finite number of frequencies at which the signal oscillates

Cooperative Control for Multiple Autonomous Vehicles Using Descriptor Functions

The paper presents a novel methodology for the control management of a swarm of autonomous vehicles. The vehicles, or agents, may have different skills, and be employed for different missions. The methodology is based on the definition of descriptor functions that model the capabilities of the single agent and each task or mission. The swarm motion is controlled by minimizing a suitable norm of the error between agents’ descriptor functions and other descriptor functions which models the entire mission. The validity of the proposed technique is tested via numerical simulation, using different task assignment scenarios

Realization of the Sensor Web Concept for Earth Science Using Mobile Robotic Platforms

©2007 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.Presented at the 2007 IEEE Aerospace Conference,  3-10 March 2007, Big Sky, MT.DOI: 10.1109/AERO.2007.353086In this paper, we discuss the realization of a robotic mobile sensor network that allows for controlled reconfiguration of sensor assets in a decentralized manner. The motivation is to allow the construction of a new system of in-situ science observations that requires higher spatial and temporal resolution models that are needed for expanding our understanding of Earth system change. These observations could enable recording of spatial and temporal variations in environmental parameters required for such activities as monitoring of seismic activity, monitoring of civil and engineering infrastructures, and detection of toxic agents throughout a region of interest. The difficulty in establishing these science observations are that global formation properties must be achieved based on the local interactions between individual sensors. As such, we present a novel approach that allows for the sensor network to function in a decentralized manner and is thus able to achieve global formations despite individual sensor failure, limitations in communication range, and changing scientific objectives. Details on the sensing and control algorithms for controlled reconfiguration will be discussed and results of field deployment will be presented

Formation control and collision avoidance for multi-agent systems and a connection between formation infeasibility and flocking behavior.

Abstract-A feedback control strategy that achieves convergence of a multi-agent system to a desired formation configuration avoiding at the same time collisions is proposed. The collision avoidance objective is handled by a decentralized navigation function that vanishes when the desired formation tends to be realized. When inter-agent objectives that specify the desired formation cannot occur simultaneously in the state space the desired formation is infeasible. It is shown that under certain assumptions, formation infeasibility forces the agents velocity vectors to a common value at steady state. This provides a connection between formation infeasibility and flocking behavior for the multi-agent system

Locally Interacting Hybrid Systems with Embedded Graph Grammars

Abstract — In many cooperative control methods, the network topology in¤uences the evolution of its continuous states. In turn, the continuous state may in¤uence the network topology due to local restrictions on connectivity. In this paper we present a grammatical approach to modeling and controlling the switching of a system’s network topology, continuous con-trollers, and discrete modes. The approach is based on embedded graph grammars, which restrict interactions to small subgraphs and include spatial restrictions on connectivity and progress. This allows us to direct the behavior of large decentralized systems of robots. The grammatical approach also allows us to compose multiple subsystems into a larger whole in a principled manner. In this paper, we illustrate the approach by proving the correctness of a cooperative control system called the load balanced multiple rendezvous problem. I

Multi-Agent Systems

A multi-agent system (MAS) is a system composed of multiple interacting intelligent agents. Multi-agent systems can be used to solve problems which are difficult or impossible for an individual agent or monolithic system to solve. Agent systems are open and extensible systems that allow for the deployment of autonomous and proactive software components. Multi-agent systems have been brought up and used in several application domains

Unknown Input Estimation Techniques in Networks and Applications to Open Channel Hydraulic Systems

This thesis is divided in two fundamental parts, namely, the Part I, in which the theoretical background of the UIO, Consensus Algorithms and Decentralized Systems is discussed; after a collection of algorithms is presented. In the Part II, some important applicative problems are addressed and solved by means of the proposed approaches. More specifically, as for the Part I, in Chapter 1 the fundamentals regarding the matrix and graph theory are recalled. In the subsequent Chapter 2 the attention is focused on the strong observability approach, and its main features are described. Chapter 3 refers to the presentation of the Consensus algorithm, while in Chapter 4 an estimation algorithm is recalled, which allows the estimation of the state in an “overlapped” system also in presence of Unknown Inputs (in Chapter 5), which are estimated as well. In the Part II the estimation problems of flow ad infiltration, in open channel hydraulic sys- tem are solved, using a UIO approach(in Chapters 6). In Chapters 7, considering open channel hydraulic system, the UIO approach is used to solve a problem of fault detection and compensation