Outils basés simulation pour la conception d'une protection haptique sur l'axe de roulis pour hélicoptère

International audienceThe latest evolution of pilot controllers, referred to as ASSU (Active Side Sticks Units) provides static and dynamic tactile force (or haptic) feedback to the pilot at the grip. Combined with FBW (fly-by-wire), this promising technology has enhanced safety levels compared to the original mechanical linkage systems they have started to replace, while offering vast improved benefits in terms of carefree handling and pilot situational awareness. In the framework of a PhD thesis, the Information Processing and Systems Department (DTIS) of ONERA and SAFRAN Electronics & Defense have started a cooperation to evaluate the interest and the different possibilities offered by the ASSU technology to improve safety and handling qualities of rotary wing aircraft. Up to now, the design and tuning of these functions were essentially performed thanks to numerous simulator sessions or flight tests with pilots. More than just providing a set of values for the required parameters defining the cueing function (hopefully an optimal set of parameters), it is expected that the approach presented here would reduce the number of piloted simulation tests and associated difficulties of the availability of pilots, the significant amount of time and material resources. The main objective of this work is to develop a design methodology based on the simulation of the entire helicopter control loop (also including the pilot in some form) and enabling the definition and parameterization of cueing functions. Moreover, some objective criteria will be defined and used to design the force feedback laws, bringing additional means of evaluation and validation than the classical subjective rating scales

Méthodologie de conception de lois de retour d'efforts pour un mini-manche actif

International audienceSAFRAN Electronics & Defense and the Information and Systems Processing Department (DTIS) of ONERA have begun a cooperation to evaluate the interest and the methods of use of Active Side Stick Units (ASSU) to improve the safety and flight qualities of helicopters. This paper describes the work carried out to model an environment for simulation and evaluation of haptic feedback laws. An experiment, implemented in the simulator PycsHel at ONERA Salon de Provence, has brought some insight about the influence of ASSU's parameters on the detection of specific haptic feedbacks (Softstops). The results obtained will be added to the simulation model in order to allow the specification, optimal if possible, of the haptic cues.SAFRAN Electronique & Défense et le département Traitement de l'Information et Systèmes (DTIS) de l’ONERA ont entamé une coopération pour évaluer l'intérêt et les méthodes d’utilisation des mini-manches (ASSU: Active Side Stick Units) pour améliorer la sécurité et la qualité de vol des hélicoptères. Ce papier décrit les travaux menés pour modéliser un environnement de simulation et d'évaluation des lois de retour haptique. Une expérimentation, implémentée dans le simulateur PycsHel de l’ONERA Salon de Provence, a apporté un éclairage sur l’influence de paramètres de l’ASSU pour la détection de rretours haptiques spécifiques (SoftStops). Les résultats obtenus seront intégrés au modèle de simulation afin de permettre la spécification, optimale si possible, des signaux haptique

Design methodology of force feedback laws through helicopter control loop simulation

International audienceThe latest evolution of pilot controllers, referred to as ASSU (Active Side Sticks Units) provides static and dynamic tactile force (or haptic) feedback to the pilot at the grip. Combined with FBW (fly-by-wire), this promising technology has enhanced safety levels compared to the original mechanical linkage systems they have started to replace, while offering vast improved benefits in terms of carefree handling and pilot situational awareness. In the framework of a PhD thesis, the Information Processing and Systems Department (DTIS) of ONERA and SAFRAN Electronics & Defense have started a cooperation to evaluate the interest and the different possibilities offered by the ASSU technology to improve safety and handling qualities of rotary wing aircraft. Up to now, the design and tuning of these functions were essentially performed thanks to numerous simulator sessions or flight tests with pilots. More than just providing a set of values for the required parameters defining the cueing function (hopefully an optimal set of parameters), it is expected that the approach presented here would reduce the number of piloted simulation tests and associated difficulties of the availability of pilots, the significant amount of time and material resources. This paper describes the work done during the first half of the thesis. The main objective of this work is to develop a design methodology based on the simulation of the entire helicopter control loop (also including the pilot in some form) and enabling the definition and parameterization of cueing functions. Moreover, some objective criteria will be defined and used to design the force feedback laws, bringing additional means of evaluation and validation than the classical subjective rating scales

Sliced-Wasserstein on Symmetric Positive Definite Matrices for M/EEG Signals

When dealing with electro or magnetoencephalography records, many supervised prediction tasks are solved by working with covariance matrices to summarize the signals. Learning with these matrices requires using Riemanian geometry to account for their structure. In this paper, we propose a new method to deal with distributions of covariance matrices and demonstrate its computational efficiency on M/EEG multivariate time series. More specifically, we define a Sliced-Wasserstein distance between measures of symmetric positive definite matrices that comes with strong theoretical guarantees. Then, we take advantage of its properties and kernel methods to apply this distance to brain-age prediction from MEG data and compare it to state-of-the-art algorithms based on Riemannian geometry. Finally, we show that it is an efficient surrogate to the Wasserstein distance in domain adaptation for Brain Computer Interface applications

Perceptual-motor coupling betwwen Helicopter and ship during ship deck landing maneuvers

Helicopter ship landings are challenging operations appealing for further researches and innovations to help pilots safely dealing with a variety of environmental, visual and operational contexts. Indeed, landing on ship not only differs from land-based landings in the extent that the landing area is located on the flight deck, which is most of the time oscillating, but also because the visual environment is often impoverished (e.g., rain, fog, night conditions). In order to improve safety at deck-landing, the French Aerospace Lab (ONERA) and the French Defense Agency (DGA) are interested in understanding pilots’ perceptual-motor strategies involved in a such complex task so as to design ecological interfaces assisting pilots’ landing maneuvers

Feature selection for chemical sensor arrays using mutual information

We address the problem of feature selection for classifying a diverse set of chemicals using an array of metal oxide sensors. Our aim is to evaluate a filter approach to feature selection with reference to previous work, which used a wrapper approach on the same data set, and established best features and upper bounds on classification performance. We selected feature sets that exhibit the maximal mutual information with the identity of the chemicals. The selected features closely match those found to perform well in the previous study using a wrapper approach to conduct an exhaustive search of all permitted feature combinations. By comparing the classification performance of support vector machines (using features selected by mutual information) with the performance observed in the previous study, we found that while our approach does not always give the maximum possible classification performance, it always selects features that achieve classification performance approaching the optimum obtained by exhaustive search. We performed further classification using the selected feature set with some common classifiers and found that, for the selected features, Bayesian Networks gave the best performance. Finally, we compared the observed classification performances with the performance of classifiers using randomly selected features. We found that the selected features consistently outperformed randomly selected features for all tested classifiers. The mutual information filter approach is therefore a computationally efficient method for selecting near optimal features for chemical sensor arrays

Benchopt: Reproducible, efficient and collaborative optimization benchmarks

Numerical validation is at the core of machine learning research as it allows to assess the actual impact of new methods, and to confirm the agreement between theory and practice. Yet, the rapid development of the field poses several challenges: researchers are confronted with a profusion of methods to compare, limited transparency and consensus on best practices, as well as tedious re-implementation work. As a result, validation is often very partial, which can lead to wrong conclusions that slow down the progress of research. We propose Benchopt, a collaborative framework to automate, reproduce and publish optimization benchmarks in machine learning across programming languages and hardware architectures. Benchopt simplifies benchmarking for the community by providing an off-the-shelf tool for running, sharing and extending experiments. To demonstrate its broad usability, we showcase benchmarks on three standard learning tasks: $\ell_2$-regularized logistic regression, Lasso, and ResNet18 training for image classification. These benchmarks highlight key practical findings that give a more nuanced view of the state-of-the-art for these problems, showing that for practical evaluation, the devil is in the details. We hope that Benchopt will foster collaborative work in the community hence improving the reproducibility of research findings.Comment: Accepted in proceedings of NeurIPS 22; Benchopt library documentation is available at https://benchopt.github.io

Telophase Correction Refines Division Orientation in Stratified Epithelia

During organogenesis, precise control of spindle orientation balances proliferation and differentiation. In the developing murine epidermis, planar and perpendicular divisions yield symmetric and asymmetric fate outcomes, respectively. Classically, division axis specification involves centrosome migration and spindle rotation, events occurring early in mitosis. Here, we identify a novel orientation mechanism which corrects erroneous anaphase orientations during telophase. The directionality of reorientation correlates with the maintenance or loss of basal contact by the apical daughter. While the scaffolding protein LGN is known to determine initial spindle positioning, we show that LGN also functions during telophase to reorient oblique divisions toward perpendicular. The fidelity of telophase correction also relies on the tension-sensitive adherens junction proteins vinculin, α-E-catenin, and afadin. Failure of this corrective mechanism impacts tissue architecture, as persistent oblique divisions induce precocious, sustained differentiation. The division orientation plasticity provided by telophase correction may enable progenitors to adapt to local tissue needs

Modélisation et contrôle du vol d'un microdrone à ailes battantes

Recent progress made in the domain of microtechnologies allow the design of very small-sized Micro Air Vehicles (MAVs), whose wingspan is inferior than 15 cm, suitable for observation or intervention in hazardous environments. The ability to fly among obstacles or indoor requires both a great agility at low speed and silent displacements, for which the concept of flapping wings – inspired by the flight of insects and hummingbirds – seems to be the most promising. During this thesis, a flight-dynamics-oriented simulation model has been programmed, based upon previous results about the unsteady aerodynamics of insect flight. An optimization of the flapping kinematics through heuristical methods has then been performed, as well as a closed-loop control of this nonlinear and naturally unstable system. A backstepping-based approach has given very good performances for both static and dynamic domains.Les récents progrès des microtechnologies permettent le développement de drones d'envergure inférieure à 15 cm, susceptibles de réaliser des missions d'observation ou d'intervention en milieu risqué. La possibilité de vol en présence d'obstacles ou en espace fermé nécessite une grande agilité à basse vitesse et des capacités de déplacement silencieux, pour lesquelles un concept à ailes battantes – inspiré du vol des insectes et du colibri – semble être le plus prometteur. Dans le cadre de cette thèse, nous avons donc développé un modèle de simulation de type mécanique du vol d'un tel engin, à partir de résultats antérieurs concernant l'aérodynamique du vol des insectes. Nous avons ensuite déterminé les cinématiques de battement optimales à l'aide d'algorithmes heuristiques, avant de chercher à commander en boucle fermée ce système non linéaire naturellement instable. Une technique inspirée du backstepping a permis d'obtenir de très bonnes performances, en statique comme en dynamique

Modélisation simplifiée pour l'analyse, l'otimisation et le contrôle du vol d'un microdrone à ailes vibrantes

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