Alain Lambert

Safe Task Planning Integrating Uncertainties and Local Maps Federations

This paper deals with the generation of safe tasks for displacement missions of a nonholonomic mobile robot in a mapped indoor environment. The goal of this study is to plan safe actions (path-following) as well as observations (we call it local maps federation [LMF]), leading the robot to configurations where pertinent features can be sensed, thus attaining best localization relative to its environment. A path-planning method dealing with uncertainties is proposed, where both uncertainties in localization and in control of a nonholonomic mobile robot are managed. Maps uncertainties are handled using the local map concept, which is introduced as a set of the best landmarks used for planning and executing robust motion movements. The safeness of the proposed method is due to the mixing between the planning phase and the navigation phase.

Monogènes Dactylogyridae parasites de Cyprinidae du genreBarbus d'Afrique du Nord

ResuméQuinze nouvelles espèces de Monogènes Dactylogyridae sont décrites chez quinze espèces deBarbus (Teleostei, Cyprinidae) appartenant aux sous-genresB. (Barbus) etB. (Labeobarbus) en Afrique du Nord. Les barbeaux examinés proviennent des différents bassins hydrographiques du Maroc et dune localité nommée Hamman Bourgiba en Tunisie. Dans cette dernière région, le genreBarbus nest représenté que par une seule espèce:Barbus (B.) callensis. Au Maroc, on en dénombre actuellement quatorze dont quatre appartiennent au sous-genreLabeobarbus: il sagit deBarbus (L.) fritschii; B. (L.) harteti; B. (L.) paytonii etB. (L.) reinii. Les dix espèces appartenant au sous-genreBarbus sont:Barbus (B.) figuiensis; B. (B.) ksibi; B. (B.) lepineyi; B. (B.) magniatlantis; B. (B.) massaensis; B. (B.) moulouyensis; B. (B.) nasus; B. (B.) pallaryi; B. (B.) setivemensis etB. (B.) issenensis.Chaque sous-genre possède son propre pool parasitaire, à lexception deDactylogyrus marocanus n. sp., recontré sur des espèces appartenant aux deux sous-genres (B. (L.) fritschii, B. (L.) paytonii, B. (L.) harteti, B. (L.) reinii, B. (L.) nasus, B. (B.) setivimensis, B. (B.) ksibi). Sur les cinqDactylogyrus parasitant lesLabeobarbus, trois présentent une spécificité stricte vis à vis de leur hôte. Il sagit deDactylogyrus reinii n. sp. surB. (L.) reinii; D. volutus n. sp. etD. zatensis n. sp. surB. (L.) fritschii. Les espècesD. oumiensis n. sp. etD. kulindrii n. sp. présentent une spécifité stenoxène et parasitent respectivementB. (L.) harteti, B. (L.) paytonii, B. (L.) reinii etB. (L.) fritschii, B. (L.) reinii.Nous avons recontré neufDactylogyrus chez les poisson-hôtes appartenent au sous-genreBarbus. Six dentre eux ont une spécificité oïoxène; ce sont:D. guirensis n. sp.,D. atlasensis n. sp. etD. draaensis n. sp. surB. (B.) pallaryi; D. borjensis n. sp. surB. (B.) nasus etD. heteromorphus n. sp. etD. tunisiensis n. sp. surB. (B.) callensis. Les trois autres parasites ont un spectre dhôtes plus large. Il sagit deD. ksibii n. sp. recontré chezB. (B.) ksibi, B. (B.) setivimensis etB. (B.) magniatlantis; D. ksibioïdes n. sp. recontré chezB. (B.) setivimensis etB. (B.) moulouyensis. LespèceD. fimbriphallus n. sp. stenoxène, se recontre chez les poisson-hôtes du versant Sud de lAtlas et de la façade méditerranéenne à savoir:B. (B.) figuiensis, B. (B.) lepineyi, B. (B.) massaensis, B. (B.) moulouyensis, B. (B.) pallaryi etB. (B.) issenensis.Le rôle des Dactylogyridae en tant que marqueurs biogéographiques, phylogénétiques et taxonomiques est discuté à partir de la composition spécifique des communautés de Monogènes rencontrés et de leurs différents types morphologiques.AbstractFifteen new species of the Dactylogyridae (Monogenea) parasitic on fifteen species of barbels (Barbus) from North Africa (Teleostei, Cyprinidae) are described. The fishes studied belong to two subgenera,B. (Labeobarbus) andB. (Barbus), collected from various hydrographical basins of Morocco and from the Hamman Bourgiba locality in Tunisia. In the latter area, the genusBarbus is represented by onlyBarbus (Barbus) callensis. In Morocco, fourteen species are listed, four of which belong to the subgenusLabeobarbus; these areBarbus (L.) fritschii; B. (L.) harteti; B. (L.) paytonii andB. (L.) reinii. The other ten species belong to the subgenusBarbus: these areBarbus (B.) figuiensis; B. (B.) ksibi; B. (B.) lepineyi; B. (B.) magniatlantis; B. (B.) massaensis; B. (B.) moulouyensis; B. (B.) nasus; B. (B.) pallaryi; B. (B.) setivimensis andB. (B.) issenensis. Each of the two subgenera has its unique parasitic fauna, except forDactylogyrus marocanus n. sp. collected on species belonging to both subgenera (B. (L.) fritschii, B. (L.) paytonii, B. (L.) harteti, B. (L.) reinii, B. (B.) nasus, B. (B.) setivimensis andB. (B.) ksibi). Of the five monogeneans found onLabeobarbus, three appear to be specific to one host: they areDactylogyrus reinii n. sp. onB. (L.) reinii, andD. volutus n. sp. andD. zatensis n. sp. onB. (L.) fritschii. D. kulindrii n. sp. parasitisedB. (L.) reinii andB. (L.) fritschii; andD. oumiensis n. sp. occurred onB. (L.) reinii, B. (L.) paytonii andB. (L.) harteti. NineDactylogyrus species were found in fishes belonging to the subgenusBarbus. Six of them have an oïoxenous specificity: these areD. guirensis n. sp.,D. atlasensis n. sp. andD. draaensis n. sp. onB. (B.) pallaryi; D. borjensis n. sp. onB. (B.) nasus andD. heteromorphus n. sp. andD. tunisiensis n. sp. on(B.) callensis. These other three have a wider range of hosts: they areD. ksibii n. sp. collected fromB. (B.) ksibi, B. (B.) setivimensis andB. (B.) magniatlantis, andD. ksibioïdes n. sp. found onB. (B.) setivimensis andB. (B.) moulouyensis. D. fimbriphallus n. sp. is a characteristic parasite of fishes from the southern side of the Atlas mountains and the Mediterranean coast (B. (B.) figuiensis, B. (B.) lepineyi, B. (B.) massaensis, B. (B.) moulouyensis, B. (B.) pallaryi andB. (B.) issenensis).The role of dactylogyrids as biogeographical phylogenetic and taxonomic indicators is discussed in relation to the specific structure of the monogenean communities and the different morphological types found.

Safe actions and observations planning for mobile robots

Deals with the definition of safe tasks for displacement missions of a non-holonomic mobile robot in an indoor environment. The goal of this study is to plan actions (path following) as well as observations (local maps), leading the robot to configurations where pertinent features can be sensed, thus allowing the robots best localization relative to its environment. Firstly, the local map concept is introduced as a set of the best landmarks used for planning and executing robust motion movements. Secondly, a path planning method dealing with uncertainties is proposed, where both uncertainties in localization and in control of a non-holonomic mobile robot are managed. The safeness of the proposed method is due to the mixing between the planning phase and the navigation phase.

A theoretical analysis of the Extended Kalman Filter for data fusion in vehicular positioning

Global Navigation Satellite Systems (GNSS) offer a great value for many location-based services and applications. However, due to their limitations in terms of coverage, continuity, accuracy and integrity, GNSS are often fused with some extra aiding sensors. To perform the data fusion of multiple sensors it is possible to find in the literature of the field a large number of approaches that claim better accuracy, efficiency in computational terms or robustness than a reference one that is given for comparison. Normally, this reference is the Extended Kalman Filter (EKF), the most common version of the Kalman Filter for non-linear systems. However, because sensors, tests, filter tunings, etc. vary largely from one publication to another, it is not possible in many occasions to have a clear idea of the real benefits of the different methods in fair terms. This paper presents a theoretical analysis of the goodness of the EKF in loosely coupled data fusion architectures. The methodology presented can be applied to understand the limitations of different approaches for fusing multiple sensors in non-linear systems. Illustrations depict a real case with a sensor-set consisting of a GNSS, a gyro and the odometry of a road vehicle.

Static and dynamic fusion for outdoor vehicle localization

The vehicles localization is classically achieved by Bayesian methods like Extended Kaiman Filtering. Such a method provides an estimated position with its associated uncertainty. Bounded-error approaches using interval analysis work in a different way as they provide a possible set of positions. An advantage of such approaches is that the results are guaranteed and are not probabilistically defined. This paper focuses on constraints propagation techniques using static and dynamic fusion. Static fusion uses data redundancy to enhance proprioceptive data. Then dynamic fusion uses GPS in order to reduce the size of the localization box. The approach has been validated with a real outdoor vehicle.

A safe and robust path following planner for wheeled robots

This paper addresses the problem of planning a path following, robust with respect to small localization errors, allowing a mobile robot to reach safely its goal. A path planning method dealing with uncertainties is proposed where both uncertainty in localization and in control of a nonholonomic mobile robot are managed. The safeness of this method is due to the combination of the planning phase and the navigation phase by using the same localization and control processes. The localization process realized the multisensor fusion of data provided by a ring of telemetric sensors in combination with a dead-reckoning system. The robustness is due to a stabilizing controller on which the system remains stable when estimated values are used for feedback instead of exact ones. By determining a compact attractive domain bounding the regulation error, we dynamically compute a security margin during the path planning. This security margin ensures the safeness of the planned path.

Multiprocessing improvements on a low-cost system based Simultaneous Localization and Mapping

The process of Simultaneous Localization And Mapping (SLAM) has become a key topic of discussion amongst the research community in robotics and autonomous vehicle since its initiation in the latest decade. Many researchers consider SLAM ready to be instrumented for robot navigation but the implementation on a low-cost system has attracted few works. In this paper, an implementation of a SLAM algorithm is presented with regard to real-world operation. It is based on the co-design of a hardware architecture and an EKF-SLAM algorithm. Experiments were conducted with an instrumented vehicle in an a priori unknown environment. Results aim to demonstrate that our approach, based on low-cost sensors interfaced to an adequate multiprocessor architecture and an optimized algorithm, is good suitable to design embedded systems for SLAM applications in real world conditions.

Local map validity region design

Deals with the design of local maps and their associated validity region. A local map is introduced as a set of the best landmarks used for planning and executing robust motions. An automatic local map design is studied for a non-holonomic mobile robot equipped with a ring of telemetric sensors and navigating in an indoor environment. The goal of the work is to define observations and their associated sensing points, which can be both used by a planner and an execution controller. The result is a simplification of the matching process and a robust navigation completion. At execution time local navigation instead of global navigation is performed using local maps in validity region for the robot localization.

SIMD and OpenMP optimization of EKF-SLAM

SLAM algorithms are widely used by autonomous robots operating in unknown environments. Several works have presented optimizations mainly focused on the algorithm complexity. New computing technologies (SIMD coprocessors, multicore architecture) can greatly accelerate the processing time but require rethinking the algorithm implementation. This paper presents an efficient implementation of the EKF-SLAM algorithm on an embedded system implementing OMAP multi-core architecture and SIMD optimizations. The aim is to optimize the algorithm implementation to improve the localization quality. Results demonstrate that an optimized implementation is always needed to achieve efficient performances and can help to design embedded systems implementing a low-cost multi-core architecture operating under real time constraints.

Local map design for local navigation planning

This paper deals with the definition of robust tasks for displacement missions of a mobile robot in an indoor environment. For that, the concept of local map is introduced as a set of best landmarks used for planning and executing safe motions. The goal is to plan actions (path following) as well as observations (local maps), leading the robot to configurations where pertinent features can be sensed and thus allowing a best localization of the robot relative to its environment. At execution time, local navigation instead of global navigation is performed using local maps for the robot localization. For each mission, the definition of the local maps and their corresponding robot-tasks is realized automatically during the planning process. The local map design is based on a clustering method developed by Fisher (1958).