Systèmes multi-robots aériens : architecture pour la planification, la supervision et la coordination

Les robots aériens (UAV, pour Unmanned Aerial Vehicles) font l'objet d'un intérêt croissant dans la communauté robotique. Ils offrent un large champ d'applications, mais introduisent des modalités d'opération particulières (contraintes logistiques, capacités de déplacement...). Dans ce travail, nous nous intéressons aux systèmes multi-UAV : l'opération conjointe d'un certain nombre d'UAV nécessite de bâtir une architecture multi-robot qui puisse prendre en compte le potentiel et les contraintes des UAV. Dans ce but, nous introduisons une notion de "degré d'autonomie décisionnelle", qui reflète le niveau de délégation de capacités autonomes aux robots par un opérateur du système. Un exécutif générique est proposé pour interfacer, au niveau de chacun des UAV du système, les différentes configurations possibles de délégation de l'autonomie décisionnelle : celui-ci reçoit et traite des plans de tâches produits soit par un centre de contrôle en charge de tous les UAVs (bas degrés d'autonomie), soit par une couche délibérative individuelle, au niveau de chacun des UAV (hauts degrés d'autonomie). Dans ce dernier cas, nous proposons une couche délibérative permettant aux UAVs de planifier et coordonner leurs tâches, afin d'opérer conjointement dans le cadre d'une mission donnée. Cette couche délibérative regroupe un couple planificateur symbolique / raffineurs géométriques, ainsi qu'un gestionnaire d'interactions à base de modèles. Une partie des développements a été testée avec succès dans le cadre du projet européen Comets, avec 3 UAV hétérogènes (deux hélicoptères et un dirigeable). Les autres développements ont donné lieu à des tests en simulation

Biocompatible polymer-assisted dispersion of multi walled carbon nanotubes in water, application to the investigation of their ecotoxicity using Xenopus laevis amphibian larvae

Carbon nanotubes (CNTs) tend to readily agglomerate and settle down in water, while the adsorption of compounds present in natural aquatic media could enhance their dispersion and stabilization in the water column. We designed a new exposure protocol to compare the biological responses of Xenopus laevis larvae exposed in semi-static conditions to size-reduced agglomerates of multi-walled carbon nanotubes (MWCNTs) in suspension in the water column and/or to larger agglomerates. Suspensions were prepared using a combination of a non-covalent functionalization with a non-toxic polymer (either carboxymethylcellulose, CMC, or gum arabic, GA) and mechanical dispersion methods (mainly ultrasonication). The ingestion of agglomerates which have settled down was incriminated in the disruption of the intestinal transit and the assimilation of nutrients, leading to acute and chronic toxicities at the highest tested concentrations. Rise in mortality, decrease in the growth rate and induction of genotoxicity from low concentrations (1 mg/L in the presence of CMC) were evidenced in presence of suspended MWCNTs in the water column. The biological responses seemed to be modulated when GA, a potential antioxidant, was used. We hypothesized that MWCNTs should interfere mainly at the surface of the gills, acting as a potential respiratory toxicant and generally inducing indirect effects

New Concepts in the Evaluation of Biodegradation/Persistence of Chemical Substances Using a Microbial Inoculum

The European REACH Regulation (Registration, Evaluation, Authorization of CHemical substances) implies, among other things, the evaluation of the biodegradability of chemical substances produced by industry. A large set of test methods is available including detailed information on the appropriate conditions for testing. However, the inoculum used for these tests constitutes a “black box.” If biodegradation is achievable from the growth of a small group of specific microbial species with the substance as the only carbon source, the result of the test depends largely on the cell density of this group at “time zero.” If these species are relatively rare in an inoculum that is normally used, the likelihood of inoculating a test with sufficient specific cells becomes a matter of probability. Normally this probability increases with total cell density and with the diversity of species in the inoculum. Furthermore the history of the inoculum, e.g., a possible pre-exposure to the test substance or similar substances will have a significant influence on the probability. A high probability can be expected for substances that are widely used and regularly released into the environment, whereas a low probability can be expected for new xenobiotic substances that have not yet been released into the environment. Be that as it may, once the inoculum sample contains sufficient specific degraders, the performance of the biodegradation will follow a typical S shaped growth curve which depends on the specific growth rate under laboratory conditions, the so called F/M ratio (ratio between food and biomass) and the more or less toxic recalcitrant, but possible, metabolites. Normally regulators require the evaluation of the growth curve using a simple approach such as half-time. Unfortunately probability and biodegradation half-time are very often confused. As the half-time values reflect laboratory conditions which are quite different from environmental conditions (after a substance is released), these values should not be used to quantify and predict environmental behavior. The probability value could be of much greater benefit for predictions under realistic conditions. The main issue in the evaluation of probability is that the result is not based on a single inoculum from an environmental sample, but on a variety of samples. These samples can be representative of regional or local areas, climate regions, water types, and history, e.g., pristine or polluted. The above concept has provided us with a new approach, namely “Probabio.” With this approach, persistence is not only regarded as a simple intrinsic property of a substance, but also as the capability of various environmental samples to degrade a substance under realistic exposure conditions and F/M ratio

LUVMI: an innovative payload for the sampling of volatiles at the Lunar poles

The ISECG identifies one of the first exploration steps as in situ investigations of the moon or asteroids. Europe is developing payload concepts for drilling and sample analysis, a contribution to a 250kg rover as well as for sample return. To achieve these missions, ESA depends on international partnerships. Such missions will be seldom, expensive and the drill/sample site selected will be based on observations from orbit not calibrated with ground truth data. Many of the international science community’s objectives can be met at lower cost, or the chances of mission success improved and the quality of the science increased by making use of an innovative, low mass, mobile robotic payload following the LEAG recommendations. LUVMI provides a smart, low mass, innovative, modular mobile payload comprising surface and subsurface sensing with an in-situ sampling technology capable of depth-resolved extraction of volatiles, combined with a volatile analyser (mass spectrometer) capable of identifying the chemical composition of the most important volatiles. This will allow LUVMI to: traverse the lunar surface prospecting for volatiles; sample subsurface up to a depth of 10 cm (with a goal of 20 cm); extract water and other loosely bound volatiles; identify the chemical species extracted; access and sample permanently shadowed regions (PSR). The main innovation of LUVMI is to develop an in situ sampling technology capable of depth-resolved extraction of volatiles, and then to package within this tool, the analyser itself, so as to maximise transfer efficiency and minimise sample handling and its attendant mass requirements and risk of sample alteration. By building on national, EC and ESA funded research and developments, this project will develop to TRL6 instruments that together form a smart modular mobile payload that could be flight ready in 2020. The LUVMI sampling instrument will be tested in a highly representative environment including thermal, vacuum and regolith simulant and the integrated payload demonstrated in a representative environment

User-Centered Design

The successful introduction and acceptance of novel technological tools are only possible if end users are completely integrated in the design process. However, obtaining such integration of end users is not obvious, as end‐user organizations often do not consider research toward new technological aids as their core business and are therefore reluctant to engage in these kinds of activities. This chapter explains how this problem was tackled in the ICARUS project, by carefully identifying and approaching the targeted user communities and by compiling user requirements. Resulting from these user requirements, system requirements and a system architecture for the ICARUS system were deduced. An important aspect of the user‐centered design approach is that it is an iterative methodology, based on multiple intermediate operational validations by end users of the developed tools, leading to a final validation according to user‐scripted validation scenarios

International standardized procedures forin vivoevaluation of multi-walled carbon nanotube toxicity in water

The classical approach in ecotoxicological evaluation of chemical substances consists of conducting standardized bioassays on organism models. In this work, the potential impact of industrial multiwalled carbon nanotubes was investigated by ecotoxicological standardized procedures using aquatic organisms of different trophic levels, namely bacteria, green algae, invertebrates, fish, and amphibians. The results indicated (1) inhibition of growth in amphibians at 50 mg L¡1 and higher, and (2) no effects on daphnia and fish up to 100 mg L¡1. With the exception of algae (for which Fe deficiency is measured), it seems that the observed toxicity may be due to physiological effects in relation to the ingestion of carbon nanotubes not necessarily related to their intrinsic effects

Alcoholysis of palm oil mid-fraction by lipase from Rhizopus rhizopodiformis

A mycelial lipase from Rhizopus rhizopodiformis was prepared in fragment form. The lipase was examined to catalyze the alcoholysis of palm oil mid-fraction (PMF) in organic solvents. High percentage conversions of PMF to alkyl esters were achieved when methanol or propanol was used as acyl acceptor. Of the two most prevalent fatty acids in PMF, palmitic acid seemed to be preferred over oleic acid in the formation of methyl and propyl esters. The optimal ratio of oil to methanol in the alcoholysis reaction is 1 to 2 moles. The lipase exhibited high alcoholysis activities in nonpolar solvents (log P>2), such as hexane, benzene, toluene, and heptane. The enzyme showed exceptionally high thermostability

Candidate landing sites and possible traverses at the south pole of the Moon for the LUVMI-X rover

Lunar volatiles, such as water, are a crucial resource for future exploration, and their exploitation should enable the use of the Moon as a platform for even more remote destinations. As water is most likely to be found in the form of ice at the lunar poles (where surface temperatures can be as low as 40K, i.e. below the H2O temperature of sublimation in vacuum, 110K), multiple upcoming missions target the south pole (SP) cold traps. PSRs (Permanently Shadowed Regions) are especially cold enough to capture and retain volatiles but present challenging access conditions (rough topography, low illumination, low temperatures, limited Earth visibility).Funded by the EU program Horizon 2020, Space Applications Services developed the LUVMI-X rover (LUnar Volatiles Mobile Instrument eXtended), aimed at sampling and analysing lunar volatiles in the polar regions, including within a PSR. The LUVMI-X nominal payload includes an instrumented drill, the Volatiles Sampler (VS), along with a mass spectrometer, the Volatiles Analyser (VA), for surface and subsurface volatile detection and characterisation. A LIBS and a radiation detector are also included. Deployable and propellable surface science payloads are in development for inaccessible sites (e.g., some of the PSRs). This solar-powered rover has an autonomy of one or two Earth nights and can drill down to 20cm in the lunar regolith. The goal of this paper is to find suitable landing sites & traverses" paths for this rover project, that are both scientifically interesting and technically reachable.Available remote sensing imagery for the lunar SP was downloaded from the PDS or corresponding instruments" websites and added into a Geographic Information System (GIS). LUVMI-X scientific objectives and technical specifications were then translated into a list of criteria and computed in our GIS using reclassifications, buffers, and intersections. Using our GIS, reclassified data were overlaid with different weights to define and rank areas meeting the compulsory criteria. A global analysis was led to select the landing sites, followed by a local analysis (based on higher resolution data) for the establishment of traverses.The global GIS analysis allowed us to identify six regions of interest (ROI), which were compared with previous SP ROI from the literature (Lemelin, 2014; Flahaut, 2020). The identified ROI were further ranked based on areas and statistics on Sun and Earth visibilities, Diviner average surface temperatures, and H/water ice signatures (LPNS, LEND, M3).A prime ROI located between Shackleton and the Shoemaker/Faustini ridge was selected for traverse analysis. Four landing ellipses of 2x2km were located and ranked inside the ROI. Way Points (WP) were then identified to include the following scientific interests in each traverse: a boulder casting shadows, a PSR to throw a propellable payload in, an accessible PSR to go into, etc. As several WP are possible, Earth visibility was used to select the best ones. WP were then connected by using slope maps (LOLA DEM at 5m/px: avoid slopes over 20°), Earth & Sun visibilities (avoid no-go zones) and the LROC NAC mosaics at 1m/px (avoid boulders and craters), constituting a tentative traverse