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Analysis and design of a continuous parallel plate waveguide multiple beam lens antenna at Ku-band
No full textInternational audienceThis paper presents the description and analysis of a continuous parallel plate waveguide (PPW) lens-like beamformer. The main design parameters of the continuous delay lens are defined starting from an ideal bifocal constrained lens. A dedicated ray tracing analysis tool is developed to better describe propagation effects in the delay lens and provide more insight on phase aberrations versus pointing angle. Numerical results of a specific design at Ku-band are reported by comparing radiation patterns obtained with the ray tracing tool and a full-wave method. These results are also compared to the ideal bifocal constrained lens design. © 2017 Euraap
Gain enhancement of a slot antenna using multiple metasurfaces
No full textInternational audienceWe present in this paper a design of a high gain antenna for radar-based non-contact measurement systems in the k-band frequency. The proposed antenna consists of a slot on a multi-grooved metal structure (flange) and a frequency selective surface (FSS) acting as a flat lens. Often, grooved (or corrugated) surfaces and frequency selective surfaces are used to enhance antenna gain features. The combination of these two techniques could provide more gain with a small size antenna. In this sense, dimensions of both grooves and FSS are optimized to reach the maximum gain without increasing the size of the antenna. All simulations and optimizations are carried out using electromagnetic full-wave tools. Next, a prototype of the proposed antenna is manufactured and characterized. More than 15 dB of gain is obtained over the whole bandwidth with a peak gain of about 17.5 dB is measured around the frequency 24.5 GHz. © 2017 Euraap
A 32 GHz urban micro cell measurement campaign for 5G candidate spectrum region
No full textInternational audienceA 32 GHz urban microcellular measurement campaign is presented in this paper. A path loss model in line-of-sight (LOS) for the fifth-generation (5G) candidate frequency band 31.8-33.4 GHz is provided, and different key channel metrics such as omni-directional path loss, angular and delay spreads and Rician K-factor are investigated. The investigation shows that no significant difference between the 28 GHz and 32 GHz frequency bands for the studied metrics. © 2017 Euraap
Morphological impact of insulator on inkjet-printed transistor
No full textInternational audienceThis study reports on the impact of electrodes (source and drain) and insulator cross-sectional profile on the electrical behavior of printed organic field effect transistors (OFET). Varying processing technique from classical lithography to inkjet printing shows different cross-sectional profile. Indeed, due to coffee stain effect (usually considered as a drawback), inkjet-printed insulator shows wave-shaped profile although spin-coated one is perfectly smooth. However, OFET electrical behavior is not drastically impacted by insulator cross-sectional profile. Moreover, this study clearly demonstrates that independently of insulator cross sectional profile, OFET fabricated with printed-electrodes shows the worst electrical characteristics. Consequently, this work clearly demonstrates that a challenging issue for the fabrication of efficient fully-printed OFET relies on drain and source optimization (morphology or material for instance)
Emerging video coding performance: 4K quality monitoring
No full textInternational audienceThe new coding tools, developed under the Joint Exploration Model (JEM) software, have been proposed with the main goal to explore their potential coding gain in the perspective to develop a new video coding standard. In this paper we present a performance-based comparison between the JEM and HEVC reference software (HM) through a set of subjective quality assessments. Different video sequences, encoded using both JEM and HM software at different bitrates, have been used in this experiment. Results have shown that the JEM codec enables, subjectively, a quality enhancement up to 40% at similar low bit rates. © 2017 IEEE
The CoDyCo Project achievements and beyond: Towards Human Aware Whole-body Controllers for Physical Human Robot Interaction
No full textInternational audienceThe success of robots in real-world environments is largely dependent on their ability to interact with both humans and said environment. The FP7 EU project CoDyCo focused on the latter of these two challenges by exploiting both rigid and compliant contacts dynamics in the robot control problem. Regarding the former, to properly manage interaction dynamics on the robot control side, an estimation of the human behaviours and intentions is necessary. In this paper we present the building blocks of such a human-in-the-loop controller, and validate them in both simulation and on the iCub humanoid robot using a human-robot interaction scenario. In this scenario, a human assists the robot in standing up from being seated on a bench
Multi-channel broadcast in asymmetric duty cycling wireless body area networks
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Enabling Privacy in a Distributed Game-Theoretical Scheduling System for Domestic Appliances
No full textInternational audienceDemand side management (DSM) makes it possible to adjust the load experienced by the power grid while reducing the consumers' bill. Game-theoretic DSM is an appealing decentralized approach for collaboratively scheduling the usage of domestic electrical appliances within a set of households while meeting the users' preferences about the usage time. The drawback of distributed DSM protocols is that they require each user to communicate his/her own energy consumption patterns, which may leak sensitive information regarding private habits. This paper proposes a distributed privacy-friendly DSM system that preserves users' privacy by integrating data aggregation and perturbation techniques: users decide their schedule according to aggregated consumption measurements perturbed by means of additive white Gaussian noise. We evaluate the noise power and the number of users required to achieve a given privacy level, quantified by means of the increase of the information entropy of the aggregated energy consumption pattern. The performance of our proposed DSM system is compared to the one of a benchmark system that does not support privacy preservation in terms of total bill, peak demand, and convergence time. Results show that privacy can be improved at the cost of increasing the peak demand and the number of game iterations, whereas the total bill is only marginally incremented
Loi de guidage coopérative et estimateurs d'état pour système multi-agent avec réduction des communications par méthode event-triggered
No full textA large amount of research work has been recently dedicated to the study of Multi-Agent System and cooperative control. Applications to mobile robots, like unmanned air vehicles (UAVs), satellites, or aircraft have been tackled to insure complex mission such as exploration or surveillance. However, cooperative tasking requires communication between agents, and for a large number of agents, the number of communication exchanges may lead to network saturation, increased delays or loss of transferred packets, from the interest in reducing them. In event-triggered strategy, a communication is broadcast when a condition, based on chosen parameters and some threshold, is fulfilled. The main difficulty consists in determining the communication triggering condition (CTC) that will ensure the completion of the task assigned to the MAS. In a distributed strategy, each agent maintains an estimate value of others agents state to replace missing information due to limited communication. This thesis focuses on the development of distributed control laws and estimators for multi-agent system to limit the number of communication by using event-triggered strategy in the presence of perturbation with two main topics, i.e. consensus and formation control. The first part addresses the problem of distributed event-triggered communications for consensus of a multi-agent system with both general linear dynamics and state perturbations. To decrease the amount of required communications, an accurate estimator of the agent states is introduced, coupled with an estimator of the estimation error, and adaptation of communication protocol. By taking into account the control input of the agents, the proposed estimator allows to obtain a consensus with fewer communications than those obtained by a reference method. The second part proposes a strategy to reduce the number of communications for displacement-based formation control while following a desired reference trajectory. Agent dynamics are described by Euler-Lagrange models with perturbations and uncertainties on the model parameters. Several estimator structures are proposed to rebuild missing information. The proposed distributed communication triggering condition accounts for inter-agent displacements and the relative discrepancy between actual and estimated agent states. A single a priori trajectory has to be evaluated to follow the desired path. Effect of state perturbations on the formation and on the communications is analyzed. Finally, the proposed methods have been adapted to consider packet dropouts and communication delays. For both types of problems, Lyapunov stability of the MAS has been developed and absence of Zeno behavior is studied.Les systèmes multi-agents (MAS) et la commande coopérative ont fait l'objet de nombreuses recherches ces dernières années. Les domaines d'application sont très diverses et dans le cas des systèmes multi-véhicules, des approches ont été développées pour des unmanned air vehicles (UAVs), satellites, avions... Les types de missions envisagées sont des missions complexes telles l’exploration ou la surveillance de zones, la recherche et le suivi de cibles d'intérêt. Cependant, la coopération requière des échanges de communication entre les agents. Lorsque ceux-ci sont nombreux, cet échange peut conduire à des saturations du réseau, à l'augmentation des délais de transmission ou l’occurrence de pertes de paquets, d'où l'intérêt de réduire le nombre de communication. Dans les méthodes event-triggered, une communication est envoyée quand une condition, basée sur des paramètres choisis et un seuil prédéfini, est remplie. La principale difficulté est de définir une condition qui permettra de limiter les échanges sans dégrader l'exécution de la mission choisie. Dans le cas d'un système distribué, chaque agent doit maintenir une estimation de la valeur de l'état des autres agents afin de remplacer l'absence d'informations due à la communication réduite. L'objectif de cette thèse est de développer des lois de commandes et des estimateurs distribuées pour un système multi-agent afin de réduire le nombre de communication par méthode event-triggered, tout en prenant en compte la présence de perturbations. L'étude est divisée en deux grandes parties. La première décrit une méthode de communication event-triggered permettant de converger vers un consensus pour un système multi-agents de modèle d'évolution dynamique linéaire généralisée et en présence de perturbations d'état. Pour réduire les communications, un estimateur précis de l'état des agents est proposé, couplé à un estimateur de l'estimation de l'erreur, ainsi qu'un protocole de communication adapté. En prenant en compte la commande appliquée à chaque agent, l'estimateur proposé permet d'obtenir un consensus avec un nombre bien inférieur de communication que de la méthode de référence dans l'état de l'art. La seconde partie propose une stratégie de réduction de communication pour une commande de vol en formation permettant de suivre une trajectoire de référence. La dynamique des agents est décrite par un système Euler-Lagrange incluant des perturbations et des méconnaissances sur les paramètres du modèle. Différentes structures d'estimateurs sont proposées pour reconstruire les informations manquantes. La condition d'event-triggered distribuée proposée est basée sur l'écart relatif entre les positions et vitesses réelles et désirées des agents, ainsi que l'erreur relative entre la valeur estimée de l'état de l'agent et la valeur réelle. Une trajectoire de référence unique est déterminée pour guider la flotte. L'effet des perturbations sur la formation et la communication a été analysé. Enfin, les méthodes proposées ont été adaptées pour tenir compte des dégradations de performances dues aux pertes de données et aux délais de communication. Pour les deux types d'approches présentées les conditions de la stabilité du MAS ont été obtenues par l'intermédiaire de fonctions de Lyapunov et l'absence de paradoxe de Zeno a été étudiée