Pratiques nouvelles en conception industrielle: adaptation des acteurs, des objets médiateurs et des modalités de travail.

Une intervention in situ de deux mois au sein d’une équipe de conception de produits industriels (designers, dessinateurs), construite sur les méthodologies et théories de l’approche ergonomique « compréhensive », interroge les pratiques nouvelles de ces métiers depuis l’avènement de la CAO. Les « objets médiateurs » sont considérés selon leurs apports respectifs et complémentaires et non plus selon une approche dichotomique, et leur étude structure l’ensemble du recueil des données. Une méthodologie de traitement et d’analyse des informations récoltées est présentée (approche chronologique et analyses « verticales » sur base de lignes du temps). Celle-ci nous permet de tracer les nombreuses adaptations dont font preuve les acteurs tout au long de leur processus: adaptations de leurs outils et représentations, de leurs modalités de travail individuelles ou collaboratives, adaptations et développement de nouvelles compétences

On Link Estimation in Dense RPL Deployments

The Internet of Things vision foresees billions of devices to connect the physical world to the digital world. Sensing applications such as structural health monitoring, surveillance or smart buildings employ multi-hop wireless networks with high density to attain sufficient area coverage. Such applications need networking stacks and routing protocols that can scale with network size and density while remaining energy-efficient and lightweight. To this end, the IETF RoLL working group has designed the IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL). This paper discusses the problems of link quality estimation and neighbor management policies when it comes to handling high densities. We implement and evaluate different neighbor management policies and link probing techniques in Contiki’s RPL implementation. We report on our experience with a 100-node testbed with average 40-degree density. We show the sensitivity of high density routing with respect to cache sizes and routing metric initialization. Finally, we devise guidelines for design and implementation of density-scalable routing protocols

Conclusions of the symposium What does architecture think about?

À quoi pense l'architecture ? Formule détournée du projet de Pierre Macherey qui, il y a près de trente ans, interrogeait la propriété de penser de certaines oeuvres littéraires. Son ambition n'était pas d'y dévoiler une quelconque matière philosophique insoupçonnée, ni d'encourager la philosophie à exploiter les ressources de la littérature pour nourrir sa recherche d'une vérité première. La question posée par Macherey s'adressait plutôt aux conditions et aux effets de leurs rencontres, cherchant à comprendre comment deux disciplines « se réunissent sans se confondre, en dessinant des confrontations de sens singulières, énigmatiques, hybrides ». Rendre vacillante la frontière qui sépare le champ philosophique du champ littéraire, c'était donc prêter une attention renouvelée à ce qui, inextricablement, les entremêle. C’était surtout ne pas vouloir résoudre « définitivement le problème qui résulte de leur confrontation ». En ce sens, cette journée d'étude souhaiterait à la fois relancer et déplacer l’interrogation qui était celle de Macherey : quelles rencontres possibles entre architecture et philosophie ? Que peuvent produire ces rencontres, elles aussi nécessairement irrésolues ? Quels enjeux s’en dégagent ? Comment exprimer et partager ce que, ensemble, dans leur union sans fusion, elles donnent à penser

Constraint Control of a Boom Crane System

Boom cranes are among the most used cranes to lift heavy loads. Although fairly simple mechanically, from the control viewpoint this kind of crane is a nonlinear underactuated system which presents several challenges, especially when con-trolled in the presence of constraints. To solve this problem, we propose an approach based on the Explicit Reference Governor (ERG), which does not require any online optimization, thus making it computationally inexpensive. The proposed control scheme is able to steer the crane to a desired position ensuring the respect of limited joint ranges, maximum oscillation angle, and the avoidance of static obstacles.Comment: The paper was published in 37th International Symposium on Automation and Robotics in Construction (ISARC 2020

Oscillation Reduction for Knuckle Cranes

Boom cranes are among the most common material handling systems due to their simple design. Some boom cranes also have an auxiliary jib connected to the boom with a flexible joint to enhance the maneuverability and increase the workspace of the crane. Such boom cranes are commonly called knuckle boom cranes. Due to their underactuated properties, it is fairly challenging to control knuckle boom cranes. To the best of our knowledge, only a few techniques are present in the literature to control this type of cranes using approximate models of the crane. In this paper we present for the first time a complete mathematical model for this crane where it is possible to control the three rotations of the crane (known as luff, slew, and jib movement), and the cable length. One of the main challenges to control this system is how to reduce the oscillations in an effective way. In this paper we propose a nonlinear control based on energy considerations capable of guiding the crane to desired sets points while effectively reducing load oscillations. The corresponding stability and convergence analysis is proved using the LaSalle's invariance principle. Simulation results are provided to demonstrate the effectiveness and feasibility of the proposed method.Comment: This paper was published in 37th International Symposium on Automation and Robotics in Construction (ISARC 2020

Architectura & Venustas : la tentation de la folie à l’heure du capitalisme tardif

peer reviewedLate modernity and its corollary, cultural capitalism, demand that everybody adopt self-sculpture as a life project. This phenomenon, which Bell describes as an « aesthetic justification of everyday life», seems to have led cities to exhibit themselves as well –in a Bilbao effect - and architecture to put on a show of itself. But what becomes of the artistic field’s limits and of beauty in the face of this new contemporary injunction? These are the questions we intend to tackle as a contribution to the seminar on venustas in the age of world market

A cooperative instinct

Acting on a gut feeling may sometimes lead to poor decisions, but it will usually support the common good, according to a study showing that human intuition favours cooperative, rather than selfish, behaviour

Logique et philosophie analytique au service de l'atelier de conservation du patrimoine

peer reviewe

Modeling and control of 5-DoF boom crane

Automation of cranes can have a direct impact on the productivity of construction projects. In this paper, we focus on the control of one of the most used cranes, the boom crane. Tower cranes and overhead cranes have been widely studied in the literature, whereas the control of boom cranes has been investigated only by a few works. Typically, these works make use of simple models making use of a large number of simplifying assumptions (e.g. fixed length cable, assuming certain dynamics are uncoupled, etc.) A first result of this paper is to present a fairly complete nonlinear dynamic model of a boom crane taking into account all coupling dynamics and where the only simplifying assumption is that the cable is considered as rigid. The boom crane involves pitching and rotational movements, which generate complicated centrifugal forces, and consequently, equations of motion highly nonlinear. On the basis of this model, a control law has been developed able to perform position control of the crane while actively damping the oscillations of the load. The effectiveness of the approach has been tested in simulation with realistic physical parameters and tested in the presence of wind disturbances.Comment: the paper was published in 37th International Symposium on Automation and Robotics in Construction (ISARC 2020