Commande des robots destinés à interagir physiquement avec l'humain

Amener les robots à partager le même environnement que les humains apparaît l'évolution naturelle vers une robotique plus avancée, à mi-chemin entre la robotique industrielle d'aujourd'hui et les robots humanoïdes versatiles de demain. Cette éventuelle coexistence a le potentiel immense de produire un impact considérable sur plusieurs domaines liés à la vie de tous les jours tels que 1) la réhabilitation, où des thérapeutes et des robots pourront collaborer et offrir du soutien aux patients, 2) les dispositifs d'assistance robotique envers les personnes âgées ou handicapées, pour faciliter les tâches quotidiennes et 3) la chirurgie assistée. Outre ces trois domaines d'application, il est fort possible que l'impact le plus significatif de l'implantation d'un tel concept se fera au niveau du domaine manufacturier. Dans ce domaine, une synergie efficace entre l'humain et le robot peut être envisagée en combinant les formidables capacités humaines de raisonnement et d'adaptation face aux environnements non structurés avec l'inépuisable force d'un robot. Toutefois, la création d'une telle génération de robots coopératifs présente plusieurs défis, tant sur les plans mécaniques et sensoriels qu'au niveau de la commande. Cette thèse amène des réponses concrètes au défi que constitue la commande des robots destinés à interagir et coopérer avec les humains, proposant des solutions aux problèmes des mouvements coopératifs ou encore à la réaction aux collisions. Elle présente notamment une nouvelle méthode de commande basée sur l'analyse des intentions humaines en temps réel, permettant la production de mouvements coopératifs beaucoup plus intuitifs pour l'humain. Elle s'attaque aussi au problème de la stabilité du contrôleur, reconnu comme une difficulté inhérente aux robots évoluant en mouvement contraint. En effet, étant données les propriétés physiques variables de l'humain, telle la rigidité de ses bras, il est possible qu'un robot devienne instable subitement lorsque mis en contact direct avec celui-ci, engendrant ainsi d'évidents problèmes de sécurité. Au-delà des algorithmes de commande de haut niveau, cette thèse aborde de nouvelles techniques d'asservissement qui sont mieux adaptées à la mécanique particulière de ces robots. En effet, dans le but de coexister avec les humains sans risquer de les blesser, il est entendu que ces robots devront être conçus différemment, de manière à réduire leur impédance mécanique et leur capacité de transmettre de la puissance en cas de collision. Dans de telles circonstances, les régulateurs linéaires conventionnels seront bien peu efficaces dans le suivi des consignes demandées. La méthode introduite est une adaptation de la commande prédictive, bien connue dans l'industrie chimique, à la commande des manipulateurs

Superior Facial Expression, But Not Identity Recognition, in Mirror-Touch Synesthesia

Simulation models of expression recognition contend that to understand another's facial expressions, individuals map the perceived expression onto the same sensorimotor representations that are active during the experience of the perceived emotion. To investigate this view, the present study examines facial expression and identity recognition abilities in a rare group of participants who show facilitated sensorimotor simulation (mirror-touch synesthetes). Mirror-touch synesthetes experience touch on their own body when observing touch to another person. These experiences have been linked to heightened sensorimotor simulation in the shared-touch network (brain regions active during the passive observation and experience of touch). Mirror-touch synesthetes outperformed nonsynesthetic participants on measures of facial expression recognition, but not on control measures of face memory or facial identity perception. These findings imply a role for sensorimotor simulation processes in the recognition of facial affect, but not facial identity

The miR-17∼92 microRNA cluster Is a global regulator of tumor metabolism

SummaryA central hallmark of cancer cells is the reprogramming of cellular metabolism to meet the bioenergetic and biosynthetic demands of malignant growth. Here, we report that the miR-17∼92 microRNA (miRNA) cluster is an oncogenic driver of tumor metabolic reprogramming. Loss of miR-17∼92 in Myc+ tumor cells leads to a global decrease in tumor cell metabolism, affecting both glycolytic and mitochondrial metabolism, whereas increased miR-17∼92 expression is sufficient to drive increased nutrient usage by tumor cells. We mapped the metabolic control element of miR-17∼92 to the miR-17 seed family, which influences cellular metabolism and mammalian target of rapamycin complex 1 (mTORC1) signaling through negative regulation of the LKB1 tumor suppressor. miR-17-dependent tuning of LKB1 levels regulates both the metabolic potential of Myc+ lymphomas and tumor growth in vivo. Our results establish metabolic reprogramming as a central function of the oncogenic miR-17∼92 miRNA cluster that drives the progression of MYC-dependent tumors

The impact of simultaneously applying normal stress and vibrotactile stimulation for feedback of exteroceptive information

Commercially available prosthetic hands do not convey any tactile information, forcing amputees to rely solely on visual attention. A promising solution to this problem is haptics, which could lead to new prostheses in which tactile information is conveyed between the amputee and the artificial limb. However, the haptic feedback must be optimized so that amputees can use it effectively; and although several studies have examined how specific haptic feedback systems can transmit certain types of tactile information, there has not yet been much research on the effects of superposing two or more types of feedback at the same location, which might prove to be more effective than using a single type of feedback alone. This paper investigates how the simultaneous application of two different types of haptic feedback—vibration and normal stress—impacts the human sensory perception of each separate feedback type. These stimuli were applied to glabrous skin on the forearms of 14 participants. Our experiments tested whether participants experienced more accurate sensory perception, compared to vibration or normal stress alone, when vibration was applied at the same time as the normal stress, at either the same location, or at a different location 6 cm away. Results indicate that although participants' perception of the normal stress diminished when vibration was applied at the same location, the same combination improved their perception of the vibration. Apparently, vibration has a negative impact upon the ability to perceive normal stress, whether applied at the same or a different location; whereas the opposite is true for the effect of normal stress upon the perception of vibration

Large-Eddy Simulation and Conjugate Heat Transfer Around a Low-Mach Turbine Blade

International audienceDetermination of heat loads is a key issue in the design of gas turbines. In order to optimize the cooling, an exact knowledge of the heat flux and temperature distributions on the airfoils surface is necessary. Heat transfer is influenced by various factors, like pressure distribution, wakes, surface curvature, secondary flow effects, surface roughness, free stream turbulence, and separation. Each of these phenomenons is a challenge for numerical simulations. Among numerical methods, large eddy simulations (LES) offers new design paths to diminish development costs of turbines through important reductions of the number of experimental tests. In this study, LES is coupled with a thermal solver in order to investigate the flow field and heat transfer around a highly loaded low pressure water-cooled turbine vane at moderate Reynolds number (150,000). The meshing strategy (hybrid grid with layers of prisms at the wall and tetrahedra elsewhere) combined with a high fidelity LES solver gives accurate predictions of the wall heat transfer coefficient for isothermal computations. Mesh convergence underlines the known result that wall-resolved LES requires discretizations for which y+ is of the order of one. The analysis of the flow field gives a comprehensive view of the main flow features responsible for heat transfer, mainly the separation bubble on the suction side that triggers transition to a turbulent boundary layer and the massive separation region on the pressure side. Conjugate heat transfer computation gives access to the temperature distribution in the blade, which is in good agreement with experimental measurements. Finally, given the uncertainty on the coolant water temperature provided by experimentalists, uncertainty quantification allows apprehension of the effect of this parameter on the temperature distribution