High level assisted control mode based on SLAM for a remotely controlled robot

International audienceOne aim of ambient assistive technologies is to reduce long term hospitalization for elderly people, especially with pathologies such as Mild Cognitive Impairment (MCI). The smart environment assists these people and their families with safety and cognitive stimulation, so they stay as long as possible at home. The originality comes from using the robot in the elderly person's home. This robot is remote controlled by a distant user, a therapist or a relative, for determining alarming situations or for participating in stimulation exercises. Several modes are available for controlling the robot. This paper deals with an assisted control mode in which the remote user gives to the robot one goal and the robot reaches the goal by itself. During the robot movement, the user can dynamically change the current goal. An important hypothesis is that the robot has no a priori knowledge of its environment at the beginning. The knowledge will increase with time and the planned trajectory will be refreshed at two levels: a local one - faster but not always sufficient - and a global one - slower but which always finds a path if one exists. The idea is to work only with local information, using the robot sensors, the operator keeping the high level control. To assure that control, the remote operator uses video feedback and information from a laser range scanner

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Perception multicapteur : Etalonnage extrinsèque de caméra 3D, télémètre laser et caméra conventionnelle : Application au déplacement autonome et téléopéré d'un robot mobile

This work concerns multisensor perception field of study for indoor mobile robotics and especially treats the use of low cost 3D cameras together with inboard perception system of the robot (usually laser telemeter and conventionnal cameras). Each independent sensor is suffering from important weaknesses as limited field of view for low cost camears or only planar detection for laser telemeter. Using 3D camera in addition to laser telemeter allows tod etect obstacles not detected by laser telemeter but keeps the advantage of the wise field of view of common laser telemeters. 3D camears are also very useful to add visual augmentations on visual data in teleoperation control interfaces.Multisensor perception based on laser telemeter, 3D camera and conventionnal camera is only possible when extrinsic parameters are accuratly (depending on application) known. But not only accurate, the calibration process has to be simple enough to be repeatable particularly whens sensors are fixed. Calibration processes have to be executed regularly because of menanical slack. The robotic community is usually using approximative calibration because calibration is boring. In this work, we propose four new methods for extrinsic calibration. Two of these methods have been conducted to improve significantly teh simplicity and usability of calibration processes.Ce travail de thèse s'inscrit dans le domaine de la perception multicapteur pour la robotique mobile en milieu intérieur et, plus précisément, traite de l'exploitation des caméras 3D à bas coût en complément du système de perception d'un robot équipé d'un télémètre laser à balayage et de caméras conventionnelles. En effet, chacun de ces capteurs seuls souffre de défauts importants : limitation du champ de vision pour les caméras à bas coût et détection sur un unique plan pour le télémètre. L'utilisation de la caméra 3D en complément du télémètre doit permettre de percevoir les obstacles invisibles par le télémètre tout en conservant un large champ de vision. La caméra 3D apporte également des données très utiles pour augmenter les informations visuelles dans le cadre d'une interface homme-robot. La perception multicapteur basée sur le télémètre laser, la caméra 3D et la caméra conventionnelle nécessitent un étalonnage extrinsèque suffisamment précis pour l'application considérée. Au-delà de la précision, le processus lui-même se doit d'être pratique et facilement répétable puisque, notamment lorsque les capteurs sont mobiles mais pas seulement, l'étalonnage doit être renouvelé régulièrement. L'interrogation de la communauté utilisant les caméras 3D à bas coût montre que la moitié des chercheurs se contente d'un étalonnage approximatif du fait du caractère fastidieux des processus d'étalonnage. Nous proposons donc dans cette thèse quatre méthodes d'étalonnage extrinsèque dont deux en particulier pour lesquelles l'objectif est d'améliorer significativement la praticité du processus d'étalonnage

A multi-sensor calibration toolbox for Kinect : Application to Kinect and laser range finder fusion.

International audienceIn most of indoor mobile robot navigation, obstacle avoidance is a crucial task and should be reliable. Fusion of sources of data can be used to detect any obstacle shapes. Laser range finder is usually used to deal with this task in presence of simple obstacles. 3D sensors as Kinect provide 3D information which can be used for more complex obstacle detection. However, opposed to laser range finder, Kinect has strong limitations like measuring range or the field of view. This paper proposes a full calibration of different sensors which can be coupled with the Kinect sensor by Microsoft. The approach can also be applied to a large variety of 3D depth sensors like time-of-flight cameras, 3D LIDAR or RADAR. The basic idea is to compute the Euclidian transformation between each sensor. In this paper, we show that chessboard methods used to calibrate color cameras can be extended to deal with 3D depth sensors like Kinect. We show in a real experiment, the benefit of the fusion based on the calibration results, in order to detect complex obstacles reliably

Fully automatic extrinsic calibration of RGB-D system using two views of natural scene

International audienceRGB-D sensor, like low cost Kinect, are widely used in robotics applications. Obstacle Avoidance (OA), Simultaneous Localization And Mapping (SLAM), Mobile Object Tracking (MOT) all are needing accurate information about the position of objects in the environment. 3D cameras are really convenient to realize those tasks but as low cost sensors, they have to be completed by other sensors:cameras, laser range finders, US or IR telemeters. In order to exploit all data sensors in a same algorithm, we have to express these data in a common reference frame. In other words we have to know the rigid transformation between sensor frames. In this paper, we propose a new method to retrieve rigid transformation (known as extrinsic parameters in calibration process) between a depth camera and a conventional camera. We show that such a method is accurate enough without the need of an user interaction nor a special calibration pattern unlike other common calibration processes

Deep Multi-View Stereo Gone Wild

International audienceDeep multi-view stereo (MVS) methods have been developed and extensively compared on simple datasets, where they now outperform classical approaches. In this paper, we ask whether the conclusions reached in controlled scenarios are still valid when working with Internet photo collections. We propose a methodology for evaluation and explore the influence of three aspects of deep MVS methods: network architecture, training data, and supervision. We make several key observations, which we extensively validate quantitatively and qualitatively, both for depth prediction and complete 3D reconstructions. First, complex unsupervised approaches cannot train on data in the wild. Our new approach makes it possible with three key elements: upsampling the output, softmin based aggregation and a single reconstruction loss. Second, supervised deep depthmap-based MVS methods are state-of-the art for reconstruction of few internet images. Finally, our evaluation provides very different results than usual ones. This shows that evaluation in uncontrolled scenarios is important for new architectures

Benefits and limits of sediment toxicity tests as an aid to decision-making

International audienceWith respect to the management of dredged sediments, a crucial issue is whether the removed materials (watered and/or processed) are disposed of or reused in an environmentally sound manner. In this context, the number of studies dealing with hazard or risk assessment has exponentially increased. This emphasis has resulted in the promotion and application of a very large variety of ecotoxicological tests. As a consequence, there is a clear need to highlight the scope and limitations of these tests for their appropriate selection and interpretation. In this paper we discuss the choice, implementation and interpretation of laboratory tests carried out on aquatic organisms at various levels of biological organization. We examine some experimental tools and methods in order to determine how suitable they are in regard to the objectives for which they are employed. To make this discussion more consistent our paper is based on results from research programmes conducted for governmental organizations and industrial partners. The Laboratoire des Sciences de l'Environnement (LSE) was involved with Cemagref de Lyon in a first methodological programme on risk assessment of scenarios of dredged sediment deposition. Another programme for a chemical company was implemented to assess the benefits of a physico-chemical treatment applied to contaminated dredged sediments in a scenario of reuse or deposit in gravel pits. Currently, the LSE is working on a programme of risk assessment for road sediments in valorization scenarios. From these programmes, we expose how single-species tests, as well as more complex bioassays and microcosm tests, can be used in an iterative step of risk assessment. Concerning microcosm tests, we also introduce a more realistic system that has been designed to simulate natural hydraulic conditions of gravel pits to assess the effects of toxicants on gravel pit aquatic biota during the sediment immersion phase and the sediment post-deposition phase (paper in preparation). The benefits of these ecotoxicological approaches are underlined, but limits are discussed with regard to several criteria: ecological relevance, realism, use for decision-making, cost and complexity of methods involve

Evaluation ecotoxicologique de sediments contamines ou de materiaux de dragage II : application au canal de l'Est branche sud

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : GR 1834 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Low incidence of SARS-CoV-2, risk factors of mortality and the course of illness in the French national cohort of dialysis patients

International audienceThe aim of this study was to estimate the incidence of COVID-19 disease in the French national population of dialysis patients, their course of illness and to identify the risk factors associated with mortality. Our study included all patients on dialysis recorded in the French REIN Registry in April 2020. Clinical characteristics at last follow-up and the evolution of COVID-19 illness severity over time were recorded for diagnosed cases (either suspicious clinical symptoms, characteristic signs on the chest scan or a positive reverse transcription polymerase chain reaction) for SARS-CoV-2. A total of 1,621 infected patients were reported on the REIN registry from March 16th, 2020 to May 4th, 2020. Of these, 344 died. The prevalence of COVID-19 patients varied from less than 1% to 10% between regions. The probability of being a case was higher in males, patients with diabetes, those in need of assistance for transfer or treated at a self-care unit. Dialysis at home was associated with a lower probability of being infected as was being a smoker, a former smoker, having an active malignancy, or peripheral vascular disease. Mortality in diagnosed cases (21%) was associated with the same causes as in the general population. Higher age, hypoalbuminemia and the presence of an ischemic heart disease were statistically independently associated with a higher risk of death. Being treated at a selfcare unit was associated with a lower risk. Thus, our study showed a relatively low frequency of COVID-19 among dialysis patients contrary to what might have been assumed