Multi-contact Planning on Humans for Physical Assistance by Humanoid

International audienceFor robots to interact with humans in close proximity safely and efficiently, a specialized method to compute whole-body robot posture and plan contact locations is required. In our work, a humanoid robot is used as a caregiver that is performing a physical assistance task. We propose a method for formulating and initializing a non-linear optimization posture generation problem from an intuitive description of the assistance task and the result of a human point cloud processing. The proposed method allows to plan whole-body posture and contact locations on a task-specific surface of a human body, under robot equilibrium, friction cone, torque/joint limits, collision avoidance, and assistance task inherent constraints. The proposed framework can uniformly handle any arbitrary surface generated from point clouds, for autonomously planing the contact locations and interaction forces on potentially moving, movable, and deformable surfaces, which occur in direct physical human-robot interaction. We conclude the paper with examples of posture generation for physical human-robot interaction scenarios

Nouvelle intervention sur la mosaïque du sanctuaire de Mar Gabriel (Turquie orientale)

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Wafer-scale detachable monocrystalline Germanium nanomembranes for the growth of III-V materials and substrate reuse

Germanium (Ge) is increasingly used as a substrate for high-performance optoelectronic, photovoltaic, and electronic devices. These devices are usually grown on thick and rigid Ge substrates manufactured by classical wafering techniques. Nanomembranes (NMs) provide an alternative to this approach while offering wafer-scale lateral dimensions, weight reduction, limitation of waste, and cost effectiveness. Herein, we introduce the Porous germanium Efficient Epitaxial LayEr Release (PEELER) process, which consists of the fabrication of wafer-scale detachable monocrystalline Ge NMs on porous Ge (PGe) and substrate reuse. We demonstrate monocrystalline Ge NMs with surface roughness below 1 nm on top of nanoengineered void layer enabling layer detachment. Furthermore, these Ge NMs exhibit compatibility with the growth of III-V materials. High-resolution transmission electron microscopy (HRTEM) characterization shows Ge NMs crystallinity and high-resolution X-ray diffraction (HRXRD) reciprocal space mapping endorses high-quality GaAs layers. Finally, we demonstrate the chemical reconditioning process of the Ge substrate, allowing its reuse, to produce multiple free-standing NMs from a single parent wafer. The PEELER process significantly reduces the consumption of Ge during the fabrication process which paves the way for a new generation of low-cost flexible optoelectronics devices.Comment: 17 pages and 6 figures along with 3 figures in supporting informatio

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P < 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Regards croisés sur le patrimoine culturel des communautés syriaques de Turquie

Les pages qui suivent proposent d’éclairer certains aspects des liens que la minorité des Syriaques de Turquie entretient avec son patrimoine culturel. Ce dernier est autant matériel (transmission et protection de biens immobiliers privés ; restauration et entretien d’édifices religieux) qu’immatériel (ensei­gnement, notamment, de la langue syriaque dans des écoles spécifiques). Le processus de patrimonialisation de l’héritage syriaque s’adosse au désir de la communauté – menacée de dispariti..

Etude numérique et expérimentale du comportement vibroacoustique des clapets de compresseur frigorifique

Le compresseur à' piston, malgré sa conception ancienne, reste encore l'une des technologies de compresseur les plus utilisées. Il est présent entre autre dans les machines frigorifiques domestiques. Au cœur de la boucle frigorifique, il est la seule partie mécaniquement active du système et est donc à l'origine des principales nuisances sonores et vibratoires. D'admission ou de refoulement, le clapet est une pièce maîtresse. En effet, sa présence et son action conditionnent le comportement global du compresseur. Ce travail de thèse se propose d'étudier la dynamique de ces pièces pendant le cycle de compression en tenant compte des principaux phénomènes physiques présents dans leur environnement proche. L'objectif, in fine, est la conception d'un outil de prédimensionnement intégrant les besoins industriels. Aussi, un modèle numérique s'appuyant sur plusieurs domaines de la physique a été développé: thermodynamique, mécanique mais aussi tribologie. Une fois mis en place sur le plan informatique, plusieurs paramètres du modèle sont recalés par le biais de montages s' appu yant notamment sur la vélocimétrie laser et la profilométrie. Dans le but de diminuer le temps de calcul, plusieurs artifices sont utilisés, entre autre une décomposition et une troncature modales. L'utilisation d'une telle méthode dans un cadre non linéaire (contact) est justifiée pour cette application. Les résultats numériques sont par la suite confrontés à des mesures effectuées sur un compresseur instrumenté en fonctionnement réel.COMPIEGNE-BU (601592101) / SudocSudocFranceF

Compliant Robot Motion Regulated via Proprioceptive Sensor Based Contact Observer

International audienceIn this paper, we present developments of a real-time compliant motion control for a personal humanoid robot. Our approach allows to interpret and react to human guidance through touch using only joint encoders measurements to monitor contact direction and intensity on both static and moving links. This novel method is developed with consideration of minimal sensor requirement of the hardware platform to meet high affordability criteria. We demonstrate performances in experiments with a humanoid robot Pepper

Discrete s-convex extremal distributions: Theory and applications

Given a nondegenerated moment space with s fixed moments, explicit formulas for the discrete s-convex extremal distribution have been derived for s = 1, 2, 3. If s = 4, only the maximal distribution is known. This paper goes beyond this limitation and proposes a method to derive explicit expressions for general nonnegative integer s. In particular, we derive explicitly the discrete 4-convex maximal distribution. As an application, we show how this theory allows to bound the probability of extinction in a Galton-Watson branching process. Keywords: s-convex orders, moment spaces, stochastic extrema, Lundberg’s bound, branching process.

Contact Observer for Humanoid Robot Pepper based on Tracking Joint Position Discrepancies

International audienceIn order to enable efficient control of a human-humanoid in physical contact settings, a real-time solution for a contact observer is required. We propose a novel approach for proprioceptive sensor based contact sensing suitable for affordable personal robots with no force/torque or electric current sensing. We combine robot model knowledge and the output of acceleration resolved quadratic programming whole-body controller to make a prediction of expected position tracking error for computing our proposed contact observer signal. We demonstrate the efficiency of our approach in the experiments of contact detection and estimation of collision direction and intensity on a real humanoid robot Pepper platform controlled by a task-space multi-objective quadratic programming controller

Nouvelle intervention sur la mosaïque du sanctuaire de Mar Gabriel (Turquie orientale)

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