Multi‑Agent Foraging: state‑of‑the‑art and research challenges

International audienceThe foraging task is one of the canonical testbeds for cooperative robotics, in which a collection of robots has to search and transport objects to specific storage point(s). In this paper, we investigate the Multi-Agent Foraging (MAF) problem from several perspectives that we analyze in depth. First, we define the Foraging Problem according to literature definitions. Then we analyze previously proposed taxonomies, and propose a new foraging taxonomy characterized by four principal axes: Environment, Collective, Strategy and Simulation, summarize related foraging works and classify them through our new foraging taxonomy. Then, we discuss the real implementation of MAF and present a comparison between some related foraging works considering important features that show extensibility, reliability and scalability of MAF systems. Finally we present and discuss recent trends in this field, emphasizing the various challenges that could enhance the existing MAF solutions and make them realistic

An Energy-Aware Algorithm for Large Scale Foraging Systems

International audienceThe foraging task is one of the canonical testbeds for cooperative robotics, in which a collection of coordinated robots have to find and transport one or more objects to one or more specific storage points. Swarm robotics has been widely considered in such situations, due to its strengths such as robustness, simplicity and scalability. Typical multi-robot foraging systems currently consider tens to hundreds of agents. This paper presents a new algorithm called Energy-aware Cooperative Switching Algorithm for Foraging (EC-SAF) that manages thousands of robots. We investigate therefore the scalability of EC-SAF algorithm and the parameters that can affect energy efficiency overtime. Results indicate that EC-SAF is scalable and effective in reducing swarm energy consumption compared to an energy-aware version of the reference well-known c-marking algorithm (Ec-marking)

Exploring unknown environments with multi-modal locomotion swarm

International audienceSwarm robotics is focused on creating intelligent systems from large number of simple robots. The majority of nowadays robots are bound to operations within mono-modal locomotion (i.e. land, air or water). However, some animals have the capacity to alter their locomotion modalities to suit various terrains, operating at high levels of competence in a range of substrates. One of the most significant challenges in bio-inspired robotics is to determine how to use multi-modal locomotion to help robots perform a variety of tasks. In this paper, we investigate the use of multi-modal locomotion on a swarm of robots through a multi-target search algorithm inspired from the behavior of flying ants. Features of swarm intelligence such as distributivity, robustness and scalability are ensured by the proposed algorithm. Although the simplicity of movement policies of each agent, complex and efficient exploration is achieved at the team level

A Distributed Foraging Algorithm Based on Artificial Potential Field

International audienceSimple collections of agents that perform collectively and use distributed control algorithms constitute the interests of swarm robotics. A key issue to improve system performances is to effectively coordinate the team of agents. We present in this paper a multi-agent foraging algorithm called Cooperative-Color Marking Foraging Agents (C-CMFA). It uses the coordination rules of the S-MASA (Stigmergic Multi-Ant Search Area) algorithm to (i) speed up the search process and (ii) allow agents to build an optimal Artificial Potential Field (APF) simultaneously while exploring. To benefit from multiple robots, we add one cooperation rule in the algorithm to attract large number of agents to the found food. This algorithm constitutes a distributed and synchronous version of the c-marking algorithm. Simulation results in comparison with the c-marking one show the superiority of C-CMFA in different environment configurations

A Decentralized Ant Colony Foraging Model Using Only Stigmergic Communication

International audienceThis paper addresses the problem of foraging by a coordinated team of robots. This coordination is achieved by markers deposited by robots. In this paper, we present a novel decentralized behavioral model for multi robot foraging named cooperative c-marking agent model. In such model, each robot makes a decision according to the affluence of resource locations, either to spread information on a large scale in order to attract more agents or the opposite. Simulation results show that the proposed model outperforms the well-known c-marking agent model

Stigmergic MASA: A Stigmergy Based Algorithm for Multi-Target Search

International audienceWe explore the on-line problem of coverage where multiple agents have to find a target whose position is unknown, and without a prior global information about the environment. In this paper a novel algorithm for multi-target search is described, it is inspired from water vortex dynamics and based on the principle of pheromone-based communication. According to this algorithm, called Stigmergic MASA (for "Multi Ant Search Area"), the agents search nearby their base incrementally using turns around their center and around each other, until the target is found, with only a group of simple distributed cooperative Ant like agents, which communicate indirectly via depositing/detecting markers. This work improves the search performance in comparison with pure random walks, we show the obtained results using computer simulations

Lévy Walk-based Search Strategy: Application to Destructive Foraging

International audienceIn this paper a Search strategy based on Lévy Walk is proposed. Lévy Walk increases the diversity of solutions, and constitutes good strategies to move away from local to global search. The amount of exploration and exploitation and the fine balance between them determine the efficiency of search algorithm. The highly diffusive behavior of the original Lévy Walk algorithm results in more global search. Thus, in the proposed algorithm, the time spent in local search is increased according to the fluctuation of the searched region. Moreover, a case study on destructive foraging is presented in this paper, with the aim to apply it to several swarm robotics problems. In order to present simulations in a finite two dimensional landscape with a limited number of clustered and scattered targets, the ArGOS simulator has been used

Towards a Reference Architecture for Swarm Intelligence-based Internet of Things

International audienceThe Internet of Things (IoT) represents the global network which interconnects digital and physical entities. It aims at providing objects with intelligence that allows them to perceive, decide and cooperate with other objects, machines, systems and even humans to enable a whole new class of applications and services. Agent-Based Computing paradigm has been exploited to deal with the IoT system development. Many research works focus on making objects able to think by themselves thus imitating human brain. Swarm Intelligence studies the collective behavior of systems composed of many individuals who interact locally with each other and with their environment using decentralized and self-organized control to achieve complex tasks. Swarm intelligence-based systems provide decentralized, self-organized and robust systems with consideration of coordination frameworks. We explore in this paper the exploitation of swarm intelligence-based features in IoT-based systems. Therefore, we present a reference swarm-based architectural model that enables cooperation among devices in IoT systems

Conception et caractérisation d'antennes imprimées pour systèmes Ultra-Large-Bande impulsionnels

The recent use of Ultra Wide Band technology in telecommunication implies the study of appropriated antennas. This thesis presents the needs of efficient and characterized antennas but also the keys related to their conception. A state of the art of UWB antennas is proposed and a bow-tie structure is chosen for optimization. A novel triangular CPW-fed printed antenna is then presented. This shape allows a 50 Ω impedance matching, an omnidirectionnal radiation pattern, a limited size and a low cost. A triangular slot and capacitive effects are introduced in the radiating part of the antenna in order to confer a better matching over a wider bandwidth, and a smaller overall size to the structure. A second work was carried out on ground planes shape to obtain more constant radiation patterns with frequency. The measurements of four realized antennas have validated the simulated results. The combined effects of these improvements on the final antenna structure result in an size reduction of 70 %. An elliptical CPW-fed printed antenna has also been studied and realized. Time domain measurements were also necessary to characterize the antennas. The procedure and data processing are first presented and validated. Antenna transmit and receive transfer functions have been differentiated. This characterization in several plans and directions allows us to calculate the distortion of a reference pulse during his radiation by the antenna. The dispersion that occurs can then be calculated and compared depending on antenna under test and direction.L'essor récent des communications Ultra Large Bande a nécessité des antennes spécialement adaptées à cette technologie. Cette thèse explicite les besoins en éléments rayonnants caractérisés ainsi que les contraintes spécifiques liées à la conception d'antennes pour ces systèmes. Un état de l'art des antennes large bande valide le choix d'une base d'étude. L'optimisation d'une antenne papillon précède la présentation d'une nouvelle structure imprimée. Cette géométrie d'antenne alimentée par guide d'onde coplanaire lui confère une adaptation d'impédance à 50 Ω, un rayonnement omnidirectionnel, ainsi qu'un encombrement et un coût limités. L'insertion d'une ouverture triangulaire ainsi que de fentes capacitives au sein du triangle rayonnant améliore l'adaptation, élargit la bande passante et réduit l'encombrement. Un second travail a consisté à obtenir un rayonnement moins directif en adoptant des formes de plans de masse latéraux appropriés. Les résultats simulés ont été validés par quatre réalisations. L'effet combiné des améliorations permet à l'antenne finale de présenter une réduction de taille de 70 %. Enfin, une antenne imprimée elliptique alimentée par CPW est étudiée et réalisée. Des mesures temporelles ont été nécessaires afin de caractériser les antennes. Le mode opératoire et les traitements appliqués sont décrits et validés. Les fonctions de transfert des antennes en émission et réception sont séparées. Leur caractérisation dans différentes directions de propagation permet de présenter les déformations subies par une impulsion référence lors de son rayonnement par les antennes. Leur dispersion a ainsi pu être comparée selon la direction et l'antenne utilisée

Antenne ETSA "Exponential Tapered Slot Antenna" miniature pour radar à pénétration de surface

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