AntBot, un robot fourmi qui navigue sans GPS

National audienceLa navigation autonome constitue l’un des enjeux majeurs de notre époque. Il est donc impératif d’augmenter la précision et la fiabilité des systèmes de navigation. En s’inspirant des modalités sensorielles des fourmis du désert, il est possible de concevoir de nouvelles stratégies innovantes. Ainsi, en observant le ciel, le robot AntBot est capable de s’orienter et de revenir à sa base avec une précision 100 fois meilleure que celle du GPS

Neuromorphic computing for attitude estimation onboard quadrotors

Compelling evidence has been given for the high energy efficiency and update rates of neuromorphic processors, with performance beyond what standard Von Neumann architectures can achieve. Such promising features could be advantageous in critical embedded systems, especially in robotics. To date, the constraints inherent in robots (e.g., size and weight, battery autonomy, available sensors, computing resources, processing time, etc.), and particularly in aerial vehicles, severely hamper the performance of fully-autonomous on-board control, including sensor processing and state estimation. In this work, we propose a spiking neural network (SNN) capable of estimating the pitch and roll angles of a quadrotor in highly dynamic movements from 6-degree of freedom Inertial Measurement Unit (IMU) data. With only 150 neurons and a limited training dataset obtained using a quadrotor in a real world setup, the network shows competitive results as compared to state-of-the-art, non-neuromorphic attitude estimators. The proposed architecture was successfully tested on the Loihi neuromorphic processor on-board a quadrotor to estimate the attitude when flying. Our results show the robustness of neuromorphic attitude estimation and pave the way towards energy-efficient, fully autonomous control of quadrotors with dedicated neuromorphic computing systems

Bio-inspired autonomous navigation applied to a hexapod robot

Le développement de la navigation autonome est devenu l'un des enjeux technologiques majeurs du 21ème siècle. Aucune solution fiable ne saurait faire l'économie du GPS ni même des caméras, très répandues en robotique. Cette thèse vise à mettre en place une nouvelle stratégie de navigation parcimonieuse inspirée des fourmis du désert Cataglyphis afin de localiser un robot terrestre mobile hexapode. S'inspirant de l’œil composé des fourmis, un compas céleste minimaliste doté de deux photodiodes sensibles au rayonnement UV et surmontées de filtres linéaires polarisants, permet d'acquérir l'angle de polarisation de la lumière du ciel, lequel sert de cap en navigation terrestre. Le compas céleste a démontré d'excellentes performances, résilientes à l’égard des conditions météorologiques. Les tâches de navigation ont été réalisées par le robot hexapode AntBot, équipé du compas céleste et d'un capteur de flux optique constitué de 12 pixels auto-adaptatifs dont la réponse mime celle des cellules photoréceptrices des tortues. AntBot dispose d'un intégrateur de chemin inspiré des fourmis Cataglyphis. Ce système fusionne le cap donné par le compas céleste, la distance mesurée par le flux optique, et le nombre de pas pour déterminer la position du robot par rapport à son point de départ. Il en a résulté une erreur de navigation moyenne stable d'environ 6cm, indépendante de la forme ou de la distance des trajectoires accomplies (variant de 5 à 15m). Ces résultats montrent que cette stratégie de navigation peut être envisagée en parallèle d'un GPS, pour un coût calculatoire faible, afin de bénéficier d'un système de localisation précis, robuste et efficace.Autonomous navigation is one of the leading technological challenges of the 21st century and is currently solved using GPS and camera-based strategies. This PhD thesis aims at setting up new navigation strategies inspired by desert ants Cataglyphis, requiring few resources and tested on board a hexapod walking robot. Taking inspiration from the ants' compound eye, a novel celestial compass - composed of just two ultraviolet-sensitive photodiodes topped with rotating linear polarizers - provides measurements of the angle of polarization of the skylight with high angular precision. This angle is used as the vehicle's heading while navigating. This compass provided excellent performances regardless of the meteorological condition. Navigation tasks were performed with our hexapod robot AntBot equipped with both the celestial compass and an optic flow sensor, which includes 12 auto-adaptive pixels mimicking photoreceptors in turtles. AntBot has a path integrator navigation system inspired by behavioral studies in desert ants Cataglyphis. This strategy uses the heading given by the celestial compass, the distance measured with the optic flow sensor, and the stride integrator to determine the vehicle's position with respect to its departure location. Experiments resulted in a navigation error of approximately 6cm regardless of the shape and the length of the trajectory (varying from 5m to 15m). These results show that such navigation system can be used to complement classical techniques like GPS and vision-based ones, with a high level of robustness and efficiency, and with few computational resources needed

Le robot fourmi AntBot

En tant que processus technique, la « robotique bio-inspirée » vise à la création d’un artefact à partir de fonctions identifiées dans le vivant. Les chercheurs et chercheuses de l’Institut des sciences du mouvement de Marseille tentent d’en reproduire deux principales : la navigation sans GPS (Global Positioning System) et le repérage dans l’espace. La démarche « biorobotique » part du constat que la nature a déjà résolu un problème de roboticien : la fourmi du désert Cataglyphis est l’une des solutions. Cette fourmi est en effet capable de se localiser par rapport à son nid (point de départ), d’explorer son environnement de manière aléatoire et de rentrer en ligne droite au nid. Dans le cadre du projet « AntBot », nous développons un intégrateur de chemin permettant à un robot de revenir à son point de départ sans GPS – une boussole céleste lui permettant de mesurer son cap par rapport à la lumière polarisée du ciel. Si ce robot s’inspire de la fourmi Cataglyphis pour la vision et la stratégie de navigation, Antbot ne reproduit pas fidèlement ses structures biologiques. Le robot hexapode est bien plus grand qu’une fourmi et n’a pas d’œil composé. Confronté à un environnement naturel, ce robot permet non seulement de conforter notre compréhension des fonctions biologiques de Cataglyphis, mais aussi de concevoir de nouvelles technologies bio-inspirées.As a technical process, “bio-inspired robotics” aims to create an artifact from functions identified in living organisms. Researchers at the Marseille Institute of Motion Sciences are trying to reproduce two main ones: navigation without GPS (Global Positioning System) and location in space. The “biorobotic” approach is based on the observation that nature has already solved a robotic problem: the Cataglyphis desert ant is one of the solutions. This ant is indeed able to locate itself in relation to its nest (starting point), to explore its environment in a random way and to return in a straight line to the nest. In the framework of the "AntBot" project, we are developing a path integrator allowing a robot to return to its starting point without GPS —a celestial compass allowing it to measure its course in relation to the polarized light of the sky. While this robot is inspired by the Cataglyphis ant for vision and navigation strategy, Antbot does not faithfully reproduce its biological structures. The hexapod robot is much larger than an ant and does not have a compound eye. Confronted with a natural environment, this robot not only allows us to strengthen our understanding of the biological functions of Cataglyphis, but also to design new bio-inspired technologies

Polarized skylight-based heading measurements: a bio-inspired approach

International audienceMany insects such as desert ants, crickets, locusts, dung beetles, bees and monarch butterflies have been found to extract their navigation cues from the regular pattern of the linearly polarized skylight. These species are equipped with ommatidia in the dorsal rim area of their compound eyes, which are sensitive to the angle of polarization of the skylight. In polarization-based robotic vision, most of the sensors used so far comprise high-definition CCD or CMOS cameras topped with linear polarizers. Here we present a 2-pixel polarization-sensitive visual sensor, which was strongly inspired by the dorsal rim area of desert ants' compound eyes, designed to determine the direction of polarization of the skylight. The spectral sensitivity of this minimalistic sensor, which requires no lenses, is in the ultraviolet range. Five different methods of computing the direction of polarization were implemented and tested here. Our own methods , the Extended and AntBot method, outperformed the other three, giving a mean angular error of only 0.62° ± 0.40° (median: 0.24°) and 0.69° ± 0.52° (median: 0.39°), respectively (mean ± standard deviation). The results obtained in outdoor field studies show that our celestial compass gives excellent results at a very low computational cost, which makes it highly suitable for autonomous outdoor navigation purposes

Bio-inspired celestial compass yields new opportunities for urban localization

International audienceAutonomous navigation requires multi-sensors data fusion provided either by global navigation satellite systems (GNSS) devices, inertial measurement units, radars and cameras to achieve accurate localization. Each technological solution features advantages but suffers also from drawbacks. Data fusion aims at maintaining a strong level of accuracy and robustness to make autonomous navigation systems reliable enough to be embedded on board any autonomous vehicles. However, there are still environmental contexts in which most sensors drift or even fail to provide correct estimates. In this study, we discuss the opportunity to use a celestial compass inspired by the desert ants' visual system which is able to extract heading information from the polarization pattern of the skylight in the ultraviolet (UV) spectrum. This new sensing mode has been mounted on-top a car and tested outdoor on a 18.6km-long journey in town and compared with GNSS estimates. The UV celestial compass yielded promising performances regarding its low complexity and the root mean square error of the orientation error was only 0.55°. Our results suggest the suitability of such parsimonious insect-inspired solutions for robotic purposes in urban field like the last mile delivery

AntBot: a six-legged walking robot able to home like desert ants in outdoor environments

International audienceAutonomous outdoor navigation requires reliable multi-sensory fusion strategies. Desert ants travel widely every day showing unrivalled navigation performances, using only a few thousand neurons. In the desert, pheromones are instantly destroyed by the extreme heat. To navigate safely in this hostile environment, desert ants assess their heading from the polarized pattern of the skylight and judge the distance travelled based on both a stride-counting method and the optic flow, i.e., the rate at which the ground move across the eye. This process is called the path integration (PI). Although many methods of endowing mobile robots with means of outdoor localization have been developed recently, most of them are still prone to considerable drift and uncertainty. Here it was proposed to test several ant-inspired solutions to outdoor homing navigation problems on a legged robot using two optical sensors equipped with just 14 pixels, two of which were dedicated to an insect-inspired compass sensitive to ultraviolet light. When combining with two rotating polarized filters, this compass was equivalent to two costly arrays composed of 374 photosensors, each of which tuned to a specific polarization angle. The other 12 pixels were dedicated to optic flow measurements. Results show that our ant-inspired methods of navigation give precise performances: the mean homing error recorded during the overall trajectory was as small as 0.67% under similar lighting conditions to those encountered by ants. These findings show that ant-inspired PI strategies can be used to complement classical techniques with a high level of robustness and efficiency