Prédiction des efforts musculaires dans le système main avant-bras (modélisation, simulation, optimisation et validation)

Le projet SHARMES démarré en 2000 a comme objectif la réalisation d'une plateforme de simulation du système main et avant-bras. La prédiction dynamique des efforts musculaires responsables d'un geste est recherchée dans le cadre de ce projet. Après présentation du projet SHARMES donnée au début de ce manuscrit, une étude bibliographique sur les travaux de recherche dans le domaine de la réalisation d'une main robotique et de la conception d'un simulateur est ensuite développée. Le but du simulateur SHARMES est basé sur la reproduction hautement réaliste du système main et avant-bras. En effet, nous recherchons à estimer les efforts musculaires tout en respectant la condition de calcul temps-réel. A l'issue d'une étude anatomique, un modèle comportant 45 muscles et 24 degrés de liberté a été retenu. Une technique d'optimisation utilisant les multiplicateurs de Lagrange a été utilisée. La prédiction des efforts tendineux a été réalisée en temps-réel. La validation de ces efforts tendineux a nécessité le passage aux efforts musculaires. Une première approche de validation quantitative a été menée entre les activations prédites par optimisation et celles obtenues à partir des signaux EMG mesurés par des électrodes de surfaces. Ces premiers résultats ont validé l'approche adoptée dans ce travail ainsi que la modélisation développéeThe objective of the project SHARMES, started in 2000, is the realization of a simulation platform of the system: hand and forearm. The dynamic prediction of the muscle forces responsible for a given movement of the system is the aim of the work described within the framework of this project. After a brief presentation of SHARMES project given at the beginning of this manuscript, a bibliographical study on the research tasks in the field of the realization of a robot-like hand and design of a simulator are then developed. The aim of the simulator SHARMES is based on the highly realistic reproduction of the movement of the system. Indeed, we seek to estimate the muscle forces while preserving the real-time condition. After an anatomical study, the selected model comprises 45 muscles and 24 degrees of freedom. An optimization technique utilizing the Lagrange multiplier was used. The prediction of the tendon forces was carried out in real-time. The validation of these forces required the muscle forces computation. A first approach of quantitative validation was carried out between activations predicted by optimization and those obtained from EMG signals measured by surface electrodes. These first results checked the accuracy of the procedure used as well as the models developed.VERSAILLES-BU Sciences et IUT (786462101) / SudocPARIS-BIUSJ-Lab.Mécanique the (751055218) / SudocSudocFranceF

Design and flexible modeling of a long reach articulated carrier for inspection

International audienceThis work concerns the development of advanced robotic systems for nuclear application. The manipulator will be used for light intervention in spent fuel management facilities. The robot must meet severe specifications: small diameter, long reach within a minimum range of 6 m, high dexterity to move in constrained environment and lots of degrees of freedom (DOF) for obstacle avoidance. In order to meet these requirements, a very challenging robotic carrier (called P.A.C.) which is able to perform light intervention tasks inside high range of blind hot cells using existing engineering penetrations is developed. This long reach multi-link carrier has 11 DOF and weighs less than 30 kg. The gravity effect in the manipulator is largely compensated by a special mechanical structure (the parallelogram) that helps reducing the size of the rotation actuators used to operate the robot. Also, a glass fiber epoxy equilibrium spring is used to compensate the gravity effect over the elevation actuators. A field test is made to measure the robot's repeatability and accuracy by using a laser tracker to measure the end effector's position. Due to its size and weight, this large robot manipulator holds lots of elastic and geometric deformations. Thus it possesses a very low accuracy. A mechanical model is developed to take into account the flexibilities of the structure. This flexible model will be used to improve the accuracy of the manipulator. Applications tests were made to evaluate the ability and performances of the system to meet the operational requirements. The operation took place in an existing decontaminated hot cell and it turned out to be successful

Large-scale time-lapse microscopy of Oct4 expression in human embryonic stem cell colonies

Identification and quantification of the characteristics of stem cell preparations is critical for understanding stem cell biology and for the development and manufacturing of stem cell based therapies. We have developed image analysis and visualization software that allows effective use of time-lapse microscopy to provide spatial and dynamic information from large numbers of human embryonic stem cell colonies. To achieve statistically relevant sampling, we examined >680 colonies from 3 different preparations of cells over 5 days each, generating a total experimental dataset of 0.9 terabyte (TB). The 0.5 Giga-pixel images at each time point were represented by multi-resolution pyramids and visualized using the Deep Zoom Javascript library extended to support viewing Giga-pixel images over time and extracting data on individual colonies. We present a methodology that enables quantification of variations in nominally-identical preparations and between colonies, correlation of colony characteristics with Oct4 expression, and identification of rare events

QUAREP-LiMi: A community-driven initiative to establish guidelines for quality assessment and reproducibility for instruments and images in light microscopy

A modern day light microscope has evolved from a tool devoted to making primarily empirical observations to what is now a sophisticated , quantitative device that is an integral part of both physical and life science research. Nowadays, microscopes are found in nearly every experimental laboratory. However, despite their prevalent use in capturing and quantifying scientific phenomena, neither a thorough understanding of the principles underlying quantitative imaging techniques nor appropriate knowledge of how to calibrate, operate and maintain microscopes can be taken for granted. This is clearly demonstrated by the well-documented and widespread difficulties that are routinely encountered in evaluating acquired data and reproducing scientific experiments. Indeed, studies have shown that more than 70% of researchers have tried and failed to repeat another scientist's experiments, while more than half have even failed to reproduce their own experiments. One factor behind the reproducibility crisis of experiments published in scientific journals is the frequent underreporting of imaging methods caused by a lack of awareness and/or a lack of knowledge of the applied technique. Whereas quality control procedures for some methods used in biomedical research, such as genomics (e.g. DNA sequencing, RNA-seq) or cytometry, have been introduced (e.g. ENCODE), this issue has not been tackled for optical microscopy instrumentation and images. Although many calibration standards and protocols have been published, there is a lack of awareness and agreement on common standards and guidelines for quality assessment and reproducibility. In April 2020, the QUality Assessment and REProducibility for instruments and images in Light Microscopy (QUAREP-LiMi) initiative was formed. This initiative comprises imaging scientists from academia and industry who share a common interest in achieving a better understanding of the performance and limitations of microscopes and improved quality control (QC) in light microscopy. The ultimate goal of the QUAREP-LiMi initiative is to establish a set of common QC standards, guidelines, metadata models and tools, including detailed protocols, with the ultimate aim of improving reproducible advances in scientific research. This White Paper (1) summarizes the major obstacles identified in the field that motivated the launch of the QUAREP-LiMi initiative; (2) identifies the urgent need to address these obstacles in a grassroots manner, through a community of stakeholders including, researchers, imaging scientists, bioimage analysts, bioimage informatics developers, corporate partners, funding agencies, standards organizations, scientific publishers and observers of such; (3) outlines the current actions of the QUAREP-LiMi initiative and (4) proposes future steps that can be taken to improve the dissemination and acceptance of the proposed guidelines to manage QC. To summarize, the principal goal of the QUAREP-LiMi initiative is to improve the overall quality and reproducibility of light microscope image data by introducing broadly accepted standard practices and accurately captured image data metrics