Role-Playing Game and Learning for Young People About Sustainable Development Stakes: An Experiment in Transferring and Adapting Interdisciplinary Scientific Knowledge

The study refers to the interactions between socio-economic and natural dynamics in an island biosphere reserve by using companion modelling. This approach provides scientific results and involves interdisciplinarity. In the second phase of the study, we transferred knowledge by adapting the main research output, a role-playing game, to young people. Our goal was to introduce interactions between social and ecological systems, coastal dynamics and integrated management. Adapting the game required close collaboration between the scientists and educators in order to transform both its substance and form and to run it with an easy-to-handle ergonomic platform.Children Education, Multi-Agent Environment, Role-Playing Game

A Systematic Procedure for the Elastodynamic Modeling and Identification of Robot Manipulators

International audienceThis paper presents a systematic procedure for the elastodynamic modeling of industrial robots that is applicable to either serial or parallel manipulators. This procedure is based on a 3-D space generalization of the equivalent rigid link system (ERLS) description, the finite-element method (FEM), and the Lagrange principle. It considers flexible links and joints, and leads to generic equations of motion expressed according to the angles of the actuated joints and the independent elastic degrees of freedom. An efficient identification process through modal analysis is detailed, and the description of damping and joint behavior according to the model application is discussed. The method is applied to a 3-D delta-like parallel structure and successfully validated through an experimental impact testing-based modal analysis

A New Procedure for Tuning an Allocator and Designing a Robust High-Level Control Law for Over-Actuated Systems

This paper presents a new integrated procedure to tune a control law for overactuated mechanical systems that may encounter singularities. First, the allocator that divides the commands among the actuators is tuned thanks to a genetic optimization algorithm, that computes the optimal values of its parameters. Then, the open-loop system including the allocator is identified and a robust closed-loop controller is computed with the structured H_\infty method. Indeed, near singularities, the system and the allocator may create errors to deviate from these points or create delays to reconfigure the actuators, hence there is a need to create a closed-loop controller robust to these characteristics and to parameter variations. This procedure is carried out on a planar redundant robotic manipulator example. Simulation

Analyse critique des méthodes d’attribution des productions sigillées de l’atelier de La Madeleine (La Neuveville-devant-Nancy, Meurthe-et-Moselle)

À ce jour, aucune étude méthodique des productions sigillées de l’atelier de La Madeleine, unique atelier connu en territoire leuque, n’a été achevée et les études qui font encore référence aujourd’hui datent du début du XXe siècle. En outre, celles-ci se fondent en partie sur des fragments découverts sur des sites de consommation et dont la provenance n’est pas établie de manière incontestable. Aussi nous a-t-il paru important de proposer une analyse critique des méthodes d’identification des sigillées de La Madeleine (par le biais des marques de potiers et par celui des décors), ainsi qu’une « carte d’identité » des pâtes sigillées de l’atelier (analyse macroscopique, microscopique et chimique).La Madeleine is the only terra sigillata workshop on Leuci territory. To date, no global study of the productions from this workshop has been completed and those studies that have been made date from the start of the 20thcentury. Moreover, the studies are partly based on fragments discovered in other sites, the origin of which cannot be established with certainty. Consequently, it appeared essential to propose a critical analysis of the methods used to identify the sigillated pottery from La Madeleine (through the potters’ stamps and decorations) and also an “identity card” for each sigillated ware (based on macroscopic, microscopic and chemical analysis).Bis zum heutigen Tage wurde keine systematische Arbeit über die Sigillata aus der Werkstatt von La Madeleine, der einzigen bekannten Produktionsstätte im Gebiet der Leuker, fertiggestellt. Die Studien, die gegenwärtig noch maßgebend sind, datieren vom Beginn des 20. Jahrhunderts. Darüber hinaus beziehen sich diese Untersuchungen teilweise auf Fragmente, die an Konsumstätten gefunden wurden, und deren Herkunft nicht zweifelsfrei festgestellt werden kann. Demzufolge schien es uns wichtig, eine kritische Analyse der Methoden zur Identifizierung der Sigillata aus La Madeleine vorzulegen (anhand der Töpferstempel und Verzierungen), sowie eine Art „Personalausweis“ (makroskopische, mikroskopische und chemische Eigenschaften) der in der Werkstatt verwendeten Tone zu erstellen

Nonlinear dynamic inversion for redundant systems using the EKF formalism

This paper presents an allocator for over-actuated systems based on the Extended Kalman Filter (EKF). The main advantages of the proposed approach are the greater flexibility in handling the constraints and its real-time capabilities. Based on the literature, theoretic convergence results, which ensure the convergence towards the local optimal values looked for, are presented. Another formulation of the kinematic equations of redundant systems that meet some constraints is also proposed in order to go through and/or avoid singularities. The two formulations are combined and applied to an academic example (a planar redundant manipulator arm)

Satellite Attitude Control with a six-Control Moment Gyro Cluster tested under Microgravity Conditions

International audienceThe attitude control of a satellite equipped with a six-Control Moment Gyro (CMG) cluster is studied, taking into account CMG failure cases and constraints like actuator saturation and real-time aspects. The design of the steering law that allocates the required torques among the actuators is made complex by singularities (gimbal angles of the CMGs where no torque can be created along an axis). This paper describes the problem of a constrained allocation applied to the CMG system, and explains the selected solution. An experimental setup with six CMGs has been designed. It calculates in real-time the attitude guidance laws and control loop. Agile manoeuvres simulating nanosatellite attitude reorientations have been successfully carried out during a European Space Agency (ESA) parabolic flight campaign. The results show that the steering law performs as expected even in case of CMG failures

Robust control of rotation-floating space robots with flexible appendages for on-orbit servicing

On-orbit operations are facing a growing need for autonomous robotic systems to achieve risky and repetitive tasks. Debris removal, on-orbit servicing and in-space deployment/assembly are examples of applications considering the use of robot manipulators. The presence of large and light appendages in future spacecrafts, such as solar arrays, antennas and sun shields yields to flexible disturbances inside the structure making the control of the manipulator challenging. This paper addresses design and contro

Control of rotation-floating space robots with flexible appendages for on-orbit servicing

On-orbit operations are facing a growing need for autonomous robotic systems. Debris removal, on-orbit servicing and in-space deployment/assembly are examples of applications considering the use of robot manipulators. This paper addresses design and control problems related to autonomous space manipulator systems when using kinetic moment exchange devices in presence of flexible appendages. The paper introduces a method to develop a common control of the spacecraft base and manipulator. An extended stat

Roça sem fogo: a visão de agricultores e técnicos sobre uma experiência de manejo na Reserva de Desenvolvimento Sustentável Amanã, Amazonas, Brasil

Este ensaio apresenta uma análise crítica de um trabalho de extensão agroflorestal conduzido na Amazônia Central (Amazonas, Brasil) entre 2011 e 2013 pelo Programa de Manejo de Agroecossistemas do Instituto de Desenvolvimento Sustentável Mamirauá. As iniciativas agroflorestais basearam-se em princípios agroecológicos para promover o uso sustentável das áreas florestais. O centro da proposta foi a implementação de áreas agrícolas sem o uso do fogo – essencial para a agricultura migratória da região. No contexto da implementação das políticas internacionais de mudanças climáticas nos países em desenvolvimento, e especificamente da multiplicação dos projetos de REDD+ (Redução de Emissões provenientes de Desmatamento e Degradação florestal), iniciativas para conter o uso do fogo e para reduzir o desmatamento estão em curso na Amazônia desde 2008. O nosso estudo de caso oferece uma visão “a partir do campo” sobre a relação entre os promotores dessas políticas e as populações locais. Nós analisamos como os agricultores ribeirinhos receberam e incorporaram as iniciativas agroflorestais e a proposta para plantar sem uso do fogo nas práticas locais, focando nos resultados preliminares de oito áreas experimentais implantadas na Reserva de Desenvolvimento Sustentável Amanã entre 2011 e 2013. Com base em observações de campo, relatórios e entrevistas com os agricultores, nós descrevemos os métodos usados para implementar as áreas experimentais, as práticas alternativas de manejo apresentadas aos agricultores durante o trabalho de extensão, e como essas técnicas diferem das práticas locais. Nós refletimos sobre as lições que emergiram do encontro entre técnicos e agricultores durante as capacitações e discutimos as diversas formas com que os agricultores se envolveram nos experimentos. Nós concluímos que os futuros trabalhos de extensão agroflorestal deveriam levar em conta melhor esses parâmetros e procurar compreender as relações sociais e de parentesco através das quais os agricultores trocam conhecimento e sementes. Os atores da conservação poderão disseminar novas práticas de maneira mais efetiva com base nessas redes existentes. O sucesso das atividades em curso depende do desenvolvimento de propostas adaptadas às necessidades e aos interesses dos agricultores. Finalmente, as iniciativas deveriam ser apresentadas como um complemento e não como um substituto às práticas locais de agricultura migratória

Convergent EKF-based control allocation: general formulation and application to a Control Moment Gyro cluster

This paper addresses control allocation for redundant systems with the Extended Kalman Filter formalism. This method is compatible with the low computational power available in space environment, and presents a flexible framework to include constraints such as singularity avoidance. The convergence domain of the allocator is derived from the contraction theory framework, depending on specific parameters of the system. A general formulation is proposed to maximize the convergence domain with regard to these parameters. The method is applied to design a steering law of Control Moment Gyroscopes. Experimental tests show that the control allocation allows the actuators to work efficiently along nominal trajectories while avoiding singularities when necessary