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In most of the missions a mobile robot has to achieve – intervention in hostile environments, preparation of military intervention, mapping, etc – two main tasks have to be completed: navigation and 3D environment perception. Therefore, vision based solutions have been widely used in autonomous robotics because they provide a large amount of information useful for detection, tracking, pattern recognition and scene understanding. Nevertheless, the main limitations of this kind of system are the limited field of view and the loss of the depth perception. A 360-degree field of view offers many advantages for navigation such as easiest motion estimation using specific properties on optical flow (Mouaddib, 2005) and more robust feature extraction and tracking. The interest for omnidirectional vision has therefore been growing up significantly over the past few years and several methods are being explored to obtain a panoramic image: rotating cameras (Benosman & Devars, 1998), muti-camera systems and catadioptric sensors (Baker & Nayar, 1999). Catadioptric sensors, i.e. the combination of a camera and a mirror with revolution shape, are nevertheless the only system that can provide a panoramic image instantaneously without moving parts, and are thus well-adapted for mobile robot applications. The depth perception can be retrieved using a set of images taken from at least two different viewpoints either by moving the camera or by using several cameras at different positions. The use of the camera motion to recover the geometrical structure of the scene and the camera’s positions is known as Structure From Motion (SFM). Excellent results have been obtained during the last years with SFM approaches (Pollefeys et al., 2004; Nister, 2001), but with off-line algorithms that need to process all the images simultaneous. SFM is consequently not well-adapted to the exploration of an unknown environment because the robot needs to build the map and to localize itself in this map during its world exploration. The in-line approach, known as SLAM (Simultaneous Localization and Mapping), is one of the most active research areas in robotics since it can provide a real autonomy to a mobile robot. Some interesting results have been obtained in the last few years but principally to build 2D maps of indoor environments using laser range-finders. A survey of these algorithms can be found in the tutorials of Durrant-Whyte and Bailey (Durrant-Whyte & Bailey, 2006; Bailey & Durrant-Whyte, 2006). 1

A wireless sensor network (WSN) deployment requires the identification of optimal network nodes (sensor and sink) positions in an area of interest, to ensure the best network performances (Senouci et al. in Smart Communications in Network Technologies (SaCoNeT), 2014 International Conference on, IEEE, pp 1---6, 43). The deployment process can be divided in two main parts: (1) WSN model construction, and (2) placement optimization. Few research works were interested by WSN deployment in indoor environment, even though, most of them consider the objectives (coverage, cost, connectivity) individually without considering the sensors and sink in the same time. This paper proposes a multi-objective deployment strategy (MODS), where all important objectives are integrated. The MODS uses the multi-objective evolutionary algorithms to get near optimal solution for WSN deployment problem. An original coding solution, integrating both network cost and nodes positions is proposed. A comparative study between two evolutionary strategies (classical GA, and NSGA-II) was performed to identify the use case of each one. Obtained results showed the interest of the proposed methodology.

International audience; Maintenance of offshore wind turbines is a complex and costly undertaking which acts as a barrier to the development of this source of energy. Factors such as the size of the turbines, the size of the wind farms, their distance from the coast and meteorological conditions make it difficult for the stakeholders to select the optimal maintenance strategy. With the objective of reducing costs and duration of such operations it is important that new maintenance techniques are investigated. In this paper we propose a hybrid model of maintenance that is based on multi-agent systems; this allows for the modelling of systems with dynamic interactions between multiple parts. A multi-criteria decision algorithm has been developed to allow analysis and selection of different maintenance strategies. A cost model that includes maintenance action cost, energy loss and installation of monitoring system cost has been presented. For the purposes of this research we have developed a simulator using NetLogo software and have provided experimental results. The results show that employing the proposed hybrid maintenance strategy could increase wind farm productivity and reduce maintenance cost.

Maintenance is a crucial point to improve productivity in industry whereas systems to be maintained have an increasing complexity. Augmented Reality (AR) can reduce maintenance process time and improve quality by giving virtual information and assistance to the operator during the procedure. In this paper, a workflow is firstly presented allowing a maintenance expert to author augmented reality maintenance procedures without computer skills. Then the AR maintenance application developed is described. Based on it, we present a case study which aims to compare maintenance efficiency with respect to the market available media support used, i.e. paper, video, AR tablet or AR Smart Glasses. A set of experiments involving 24 persons is described and analyzed. The results show that augmented reality maintenance reduce number of errors done by operator than with paper for the same duration of maintenance. A qualitative analysis shows that AR systems are well accepted by the users.

International audience; This paper presents a 3-second 3D reconstruction algorithm able to process a dense geometric approximation of the surrounding environment. Image acquisition is done by a stereoscopic panoramic system with two color catadioptric cameras mounted on a mobile robot. An algorithm running on a Graphical Processing Unit (GPU) processes the 3D reconstruction in real-time. As the camera system moves, new views of the scene are used to improve the model of the scene thanks to an incremental algorithm. Then, the performance of our approach is evaluated using a synthetic image sequence

This paper proposes a scheme for a 3D metric reconstruction of the environment of a mobile robot. We first introduce the advantages of a catadioptric stereovision sensor for autonomous navigation and how we have designed it with respect to the Single Viewpoint constraint. For applications such as path generation, the robot needs a metric reconstruction of its environment, so calibration of the sensor is required. After justification of the chosen model, a calibration method to obtain the model parameters and the relative pose of the two catadioptric sensors is presented. Knowledge of all the sensor parameters yields the 3D metric reconstruction of the environment by triangulation. Tools for calibration and relative pose estimation are presented and are available on the authorpsilas Web page. The entire process has been evaluated using real data.

International audience; A stereoscopic catadioptric sensor and associated algorithms are presented to provide a relevant solution to the problem of 3D reconstruction of unknown environments. A novel calibration methodology is detailed, establishing a discrete relation between 3D points and the corresponding pixels. The 3D reconstruction adopted is an adaptation of the classic volumetric scene reconstruction technique. Complete voxels are projected onto the image planes and consistency measurements are computed on pixel surfaces. To ensure fast processings, 3D/2D matchings are processed offline and results are stored in Look-Up Tables (LUT). Calibration results are given and 3D reconstruction algorithms are validated on synthetic images. Some results obtained for real scenes are provided.