1,721,142 research outputs found
Flying robot inspired by insects : From optic flow sensing to visually guided strategies to control a Micro Aerial Vehicle
No full textDans ce travail, nous avons premièrement développé et caractérisé des capteurs de flux optique robustes aux changements de conditions lumineuses inspirés par le système visuel de la mouche et mesurant la vitesse angulaire à l'aide de l'algorithme appelé "time of travel". En particulier, nous avons comparé les performances de capteurs mesurant visuellement la vitesse angulaire en intérieur et en extérieur. Les résultats de nos capteurs bio-inspirés ont aussi été comparés avec des capteurs de souris optique. Enfin, une nouvelle implémentation de l'algorithme "time of travel" a été proposée réduisant la charge de calcul de l'unité de traitement.Dans le cadre du projet européen CurvACE (Curved Artificial Compound Eye), nous avons aussi participé au développement du premier oeil composé courbé artificiel capable de mesurer le flux optique à haute vitesse sur une large gamme de lumière ambiante. En particulier, nous avons caractérisé ce capteur et montré sa capacité à mesurer le flux optique à l'aide de plusieurs algorithmes.Finalement, nous avons aussi développé un robot aérien miniature attaché appelé BeeRotor équipé de capteurs et de stratégies de vol imitant les insectes volants et se déplaçant de manière autonome dans un tunnel contrasté. Ce robot peut expliquer comment les abeilles contrôlent leur vitesse et leur position à l'aide du flux optique, tout en démontrant que des solutions alternatives existent aux systèmes couramment utilisés en robotique. Basé seulement sur des boucles de contrôle réagissant à l'environnement, cet hélicoptère a démontré sa capacité à voler de manière autonome dans un environnement complexe et mobile.In this thesis, we first developed and characterized optic flow sensors robust to illuminance changes inspired by the visual system of the fly and computing the angular speed thanks to the "time of travel" scheme. In particular, we have compared the performances of sensors processing the visual angular speed based on a standard retina or an aVLSI retina composed of pixels automatically adapting to the background illuminance in indoor and outdoor environments. The results of such bio-inspired sensors have also been compared with optic mouse sensors which are used nowadays on Micro Aerial Vehicles to process the optic flow but only in outdoor environments. Finally, a new implementation of the "time of travel" scheme has been proposed reducing the computational load of the processing unit.In the framework of the European project CurvACE, we also participated to the design and development of the first curved artificial compound eye including fast motion detection in a very large range of illuminations. In particular, we characterized such sensor showing its ability to extract optic flow using different algorithms.Finally, we also developed a tethered miniature aerial robot equipped with sensors and control strategies mimicking flying insects navigating in a high-roof tunnel. This robot may explain how honeybees control their speed and position thanks to optic flow, while demonstrating alternative solution to classical robotic approach relying on ground-truth and metric sensors. Based only on visuomotor control loops reacting suitably to the environment, this rotorcraft has shown its ability to fly autonomously in complex and unstationary tunnels
Optic flow to control small UAVs
Full text linkAutonomous flight in confined or cluttered environments such as houses or urban canyons requires high manoeuvrability, fast mapping from sensors to actuators and very limited overall system weight. Although flying animals are well capable of coping with such situations, roboticists still have difficulties at reproducing such capabilities. This paper describes how we took inspiration from flying insects to progress toward the goal of developing small UAVs able to dynamically fly in cluttered environments. This endeavour allowed us to demonstrate a 10-gram microflyer capable of fully autonomous operation in an office-sized room using fly-inspired vision, inertial and airspeed sensors. This encouraging result is now being ported to outdoor scenarios such as low-altitude flight in urban or mountainous environments. Important is that these autonomous capabilities are achieved without the help of GPS nor active range finders, which allows to develop very lightweight autopilots.LI
Camera images from embedded Camera on a drone flying in front of walls and nettings in simulation and experimental data
No full textThis data set contains .png images taken from a drone when flying in an arena with nets on one side and plane walls on the others. The data were acquired during several flights made on different days, in a real arena or in simulations (https://gazebosim.org/home). Several parameters change across the data-sets, from orientation of the camera, type of texture used to the field-of-view of the camera.
The data are used in a journal paper in order to show a way to detect the presence of a netting via the use of the optic flow (motion parallax) taken on several layers.
The software used for data acquisition onboard the drone was python 2.7, while the system VICON tracker VRPN 3.1.1 was used for position recording (https://www.vicon.com/support/faqs/how-does-tracker-work-with-vrpn/).
The camera used was a global shutter camera ELP USBGS720P02-L36 with a 3.6 mm objective.
More details about the setup and experimental conditions can be founded in "codes/readme".
Basic codes are given in the "codes" folder in order to extract and link the data between images and csv file, taking into account the experimental bias in the data acquisition.
This project wasn't financed by a specific research project but was done during my PhD thesis.<br/
Bio-inspired visual sensors for robotic and automotive applications
No full textGrâce aux progrès réalisés dans les domaines de la robotique et des systèmes de transport intelligents (ITS), les véhicules autonomes du futur sont en train de devenir une réalité. Comme les véhicules autonomes devront se comporter en toute sécurité en présence d’autres véhicules, de piétions et d’autres objets fixes ou en mouvement, une des choses les plus importantes qu’ils doivent faire est de percevoir efficacement à la fois leur mouvement et l’environnement autour d’eux. Dans cette thèse, nous avons d’abord étudié comment des capteurs visuels bio-inspirés, qui mesurent le flux optique en 1-D en utilisant seulement quelques pixels sur la base du système visuel de la mouche, pourraient être utilisés pour améliorer les manœuvres de stationnement automatiques. Nous avons ensuite travaillé sur une nouvelle rétine de silicium bio-inspirée, en montrant que le nouveau pixel, appelé M²APIX, est capable de s’auto-adapter dans une gamme de 7 décades et de répondre de manière appropriée à des changements de luminosité rapides jusqu’à ±3 décades, tout en conservant une sensibilité aux contrastes aussi bas que 2%. Nous avons enfin développé et testé un nouveau capteur de flux optique basé sur cette rétine auto-adaptative et sur une nouvelle méthode robuste pour le calcul du flux optique, qui est robuste aux variations de lumière, textures et vibrations que l’on retrouve en milieu routier. Nous avons également construit un robot de type voiture, appelé BioCarBot, qui estime sa vitesse et son angle de braquage au moyen d’un filtre de Kalman étendu (EKF), en utilisant uniquement les mesures de flux optique délivrées par deux capteurs de ce type regardant vers le sol.Thanks to the advances in the fields of robotics and intelligent transportation systems (ITS), the autonomous vehicles of the future are gradually becoming a reality. As autonomous vehicles will have to behave safely in presence of other vehicles, pedestrians and other fixed and moving objects, one of the most important things they need to do is to effectively perceive both their motion and the environment around them. In this thesis, we first investigated how bio-inspired visual sensors, giving 1-D optic flow using a few pixels based on the findings on the fly’s visual system, could be used to improve automatic parking maneuvers. We subsequently tested a novel bio-inspired silicon retina, showing that the novel pixel, called M2APix, can auto-adapt in a 7-decade range and respond appropriately to step changes up to ±3 decades, while keeping sensitivity to contrasts as low as 2%. We lastly developed and tested a novel optic flow sensor based on this auto-adaptive retina and a new robust method for computing the optic flow, which is robust to the light levels, textures and vibrations that can be found while operating on the road. We also constructed a car-like robot, called BioCarBot, which estimates its velocity and steering angle by means of an extended Kalman filter (EKF) using only the optic flow measurements delivered by two downward-facing sensors of this kind
Simulated exploration of unknown environment by OF-shape based regulation on fully actuated hexarotor
No full textThis dataset contains dynamics parameters as well as OF acquired during simulated flight in unknown arenas made of planar surfaces. The data are organized by arenas. The method used to obtain the trajectories is described in paper “Direct optic-flow signatures guiding aerial exploration through turns” (in prep.).
The data are segmented in diffetent folder for each simulated environment, with inside a CSV file containing positions, orientations as well as OF cues computed at each simulation step, and another CSV file containing all the raw OF vectors field at each corresponding steps
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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