218 research outputs found
Les fournisseurs de mains d’oeuvres maritimes et le droit de l’Union européenne
To optimize their operating costs, many shipowners resort to manning agencies, intermediaries between them and the cosmopolitan crew of their ships, sailing, usually on the open registers advocating «absolute minimum» in social matters. This economic model based on the search for a lowering of the social cost on board ships must now reckon with the entry into force of the 2006 Maritime Labour Convention («MLC 2006»), which requires Member States to respect new obligations as to control of companies subleasing employees. Partly incorporated in the Community system, this new international social regulation nevertheless illustrates the difficulties of the European Union to develop a common response to widespread international practice of social dumping at sea. If the principle of social responsibility of States with regard to manning agencies is enshrined in the MLC 2006, the absence of Community regulation of this activity leaves the control of maritime labour companies to the sole discretion of the more diligent States in social matters
Image-based visual servoing on planar objects of unknown shape
[Notes_IRSTEA]bibl. [Departement_IRSTEA]GEAPA [TR1_IRSTEA]42 - ALITECH / CAPORALInternational audienceThis paper proposes a way to achieve positioning tasks by visual servoing, for any orientation of the camera, when the desired image of the observed object cannot be precisely described. The object is assumed to be planar and motionless but no knowledge about its shape or pose is required. To simplify the problem, first, we treat the case of a threadlike object and then we show how our approach can be generalized to an object with three particular points. The control law is based on the use of 2d visual servoing and on an estimation of a 3d parameter. Experimental results relative to objects of unknown shape are given to validate the approach. In addition, an algorithm to estimate the depth between the object and the camera is provided which leads to the dimensions of the object
Parameterized maximum likelihood method (PML): application to space-time radar localization
We present a maximum likelihood method for the localization of sources with known waveforms . It's a joint space time
radar localization which is a generalisation of recent methods to coherent signal . The obtained results are usefull in wireless
communications for the identification of propagation channel with a pilot signal . An exact maximum likelihood method is presented .
Variances of estimation and related Cramer Rao Bound are established . Simulations results illustrate the behaviour of the algorithm.Nous présentons une technique du maximum de vraisemblance qui localise des sources dont les formes d'ondes sont identiques et connues. Il s'agit d'une localisation radar conjointe direction-retard qui est une extension aux cas de signaux cohérents des méthodes actuellement utilisées et exploitant la connaissance des signaux émis. Les résultats obtenus s'appliquent de la même manière aux cas des communications mobiles pour lesquelles on veut identifier le canal de propagation à l'aide d'un signal connu. Un estimateur exact du maximum de vraisemblance est présenté. Les variances d'estimation ainsi que les bornes de Cramer-Rao sont établies. Des résultats de simulations viennent illustrer le comportement des algorithmes pour lesquels les performances sont comparées à la borne de Cramer-Rao
Localisation 2D à l'aide d'un réseau phasé très perturbé.
Dans cet article nous proposons d'améliorer la robustesse des algorithmes d'autocalibration en 2D (gisement et site) à l'aide d'une régularisation. Nous avons introduit un a priori sur le module des gains des capteurs. En effet, lorsque l'on utilise une antenne omnidirectionnelle, nous montrons que l'estimée des gains des obtenue à l'aide des éléments diagonaux de la matrice de corrélation est une information très précieuse. Nous proposons alors deux techniques de régularisation qui exploitent ces résultats. La première, grà ce à une contrainte sur la somme des modules exhibe une vitesse de convergence élevée. La seconde exploite chaque contrainte de gain simultanément et nécessite la mise en oeuvre d'une optimisation itérative. De nombreuses simulations viennent confirmer les résultats attendus et montrent les améliorations apportées
Visual Servoing from straight lines
In this paper we consider the problem of controlling a robotic system by using the projection of 3D straight lines in the
image plane of central catadioptric systems. Most of the effort in visual servoing are devoted to points, only few works
have investigated the use of lines in visual servoing with traditional cameras and none has explored the case of
omnidirectional cameras. First a generic central catadioptric interaction matrix for the projection of 3D straight lines is
derived from the projection model of an entire class of camera. Then an image-based control law is designed and
validated through simulation results and real experiments with a mobile robot.Dans cet article, nous présentons une stratégie de commande de systèmes robotiques en utilisant comme
entrées d'une boucle d'asservissement visuel des primitives relatives à la projection de droites dans le plan
image d'une caméra panoramique à point central unique. Afin de réaliser la commande d'un système
robotique par asservissement visuel, il est nécessaire d'estimer la matrice d'interaction liant les mouvements
de la caméra aux mouvements des primitives visuelles dans l'image. Dans cet article, nous dérivons la forme
analytique de la matrice d'interaction générique relative à la projection de droites à partir d'un modèle de
projection englobant la classe entière des caméras à point central unique. Elle est ensuite utilisée dans un
schéma d'asservissement visuel. Des simulations ainsi que des résultats expérimentaux sur un robot mobile
valident l'approche proposée
On-board and Ground Visual Pose Estimation Techniques for UAV Control
In this paper, two techniques to control UAVs (Unmanned Aerial Vehicles), based on visual information are presented. The first one is based on the detection and tracking of planar structures from an on-board camera, while the second one is based on the detection and 3D reconstruction of the position of the UAV based on an external camera system. Both strategies are tested with a VTOL (Vertical take-off and landing) UAV, and results show good behavior of the visual systems (precision in the estimation and frame rate) when estimating the helicopter¿s position and using the extracted information to control the UAV
Indoor robot gardening: design and implementation
This paper describes the architecture and implementation of a distributed autonomous gardening system with applications in urban/indoor precision agriculture. The garden is a mesh network of robots and plants. The gardening robots are mobile manipulators with an eye-in-hand camera. They are capable of locating plants in the garden, watering them, and locating and grasping fruit. The plants are potted cherry tomatoes enhanced with sensors and computation to monitor their well-being (e.g. soil humidity, state of fruits) and with networking to communicate servicing requests to the robots. By embedding sensing, computation, and communication into the pots, task allocation in the system is de-centrally coordinated, which makes the system scalable and robust against the failure of a centralized agent. We describe the architecture of this system and present experimental results for navigation, object recognition, and manipulation as well as challenges that lie ahead toward autonomous precision agriculture with multi-robot teams.Swiss National Science Foundation (contract number PBEL2118737)United States. Army Research Office. Multidisciplinary University Research Initiative (MURI SWARMS project W911NF-05-1-0219)National Science Foundation (U.S.) (NSF IIS-0426838)Intel Corporation (EFRI 0735953 Intel)Massachusetts Institute of Technology (UROP program)Massachusetts Institute of Technology (MSRP program
- …