Robust algorithm for calibration of robotic manipulator model

The paper focuses on the robust identification of geometrical and elastostatic parameters of robotic manipulator. The main attention is paid to the efficiency improvement of the identification algorithm. To increase the identification accuracy, it is proposed to apply the weighted least square technique that employs a new algorithm for assigning of the weighting coefficients. The latter allows taking into account variation of the measurement system precision in different directions and throughout the robot workspace. The advantages of the proposed approach are illustrated by an application example that deals with the elasto-static calibration of industrial robot.AN

Experimental Study of tool Wear Mechanisms in Conventional and High Pressure Coolant Assisted Machining of Titanium Alloy Ti17

Titanium alloys are known for their excellent mechanical properties, especially at high temperature. But this specificity of titanium alloys can cause high cutting forces as well as a significant release of heat that may entail a rapid wear of the cutting tool. To cope with these problems, research has been taken in several directions. One of these is the development of assistances for machining. In this study, we investigate the high pressure coolant assisted machining of titanium alloy Ti17. High pressure coolant consists of projecting a jet of water between the rake face of the tool and the chip. The efficiency of the process depends on the choice of the operating parameters of machining and the parameters of the water jet such as its pressure and its diameter. The use of this type of assistance improves chip breaking and increases tool life. Indeed, the machining of titanium alloys is generally accompanied by rapid wear of cutting tools, especially in rough machining. The work done focuses on the wear of uncoated tungsten carbide tools during machining of Ti17. Rough and finish machining in conventional and in high pressure coolant assistance conditions were tested. Different techniques were used in order to explain the mechanisms of wear. These tests are accompanied by measurement of cutting forces, surface roughness and tool wear. The Energy-dispersive X-ray spectroscopy (EDS) analysis technique made it possible to draw the distribution maps of alloying elements on the tool rake face. An area of material deposition on the rake face, characterized by a high concentration of titanium, was noticed. The width of this area and the concentration of titanium decreases in proportion with the increasing pressure of the coolant. The study showed that the wear mechanisms with and without high pressure coolant assistance are different. In fact, in the condition of conventional machining, temperature in the cutting zone becomes very high and, with lack of lubrication, the cutting edge deforms plastically and eventually collapses quickly. By contrast, in high pressure coolant assisted machining, this problem disappears and flank wear (VB) is stabilized at high pressure. The sudden rupture of the cutting edge observed under these conditions is due to the propagation of a notch and to the crater wear that appears at high pressure. Moreover, in rough condition, high pressure assistance made it possible to increase tool life by up to 400%.Authors would like to thank « Région des pays de la loire » for funding of the project which is part of a PhD thesi

Towards a knowledge structuring framework for decision making within industry 4.0 paradigm

International audienceThis article discusses the importance of data and knowledge structuring to allow their exploitation in emergent context of industry of the future. The complexity of integrating knowledge into decision support systems is particularly due to the heterogeneity of knowledge sources and the large volume of data to be analyzed. This problematic is challenging in the context of high-speed machining of aeronautical mechanical parts because of the high quality and safety constraints requested in this business area. To answer the above problem, this paper proposes a new semantic modeling framework covering both generic business knowledge and real time data. The application to the proposed semantic models for decision aid perspective within the SmartEmma project is also discussed

Geometric and elastostatic calibration of robotic manipulator using partial pose measurements

International audienceThe paper deals with geometric and elastostatic calibration of robotic manipulator using partial pose measurements, which do not provide the end-effector orientation. The main attention is paid to the efficiency improvement of identification procedure. In contrast to previous works, the developed calibration technique is based on the direct measurements only. To improve the identification accuracy, it is proposed to use several reference points for each manipulator configuration. This allows avoiding the problem of non-homogeneity of the least-square objective, which arises in the classical identification technique with the full-pose information (position and orientation). Its efficiency is confirmed by the comparison analysis, which deals with the accuracy evaluation of different identification strategies. The obtained theoretical results have been successfully applied to the geometric and elastostatic calibration of serial industrial robot employed in a machining work-cell for aerospace industry

L'usinage ultrasonic : cas d'application au bois

Malgré l'accroissement de l'utilisation des matériaux plastiques dans la fabrication des produits de consommation courante, le bois progresse toujours. Aussi, il faut en permanence faire évoluer les techniques de travail du bois, et en particulier, l'usinage, devenu un enjeu majeur dans cette industrie transformatrice du bois. La qualité des surfaces usinées est complexe à maîtriser car fonctionnellement précise et déterminante pour les opérations de finition. Par exemple, l'apparition de produits aqueux à faible impact environnemental (teinte) nécessite de mieux maîtriser les risques de soulèvement de fibres, non acceptables en terme d'aspect et de toucher. Ainsi de nombreuses recherches sont actuellement menées pour un meilleur compromis Qualité/Productivité. Nos travaux proposent une nouvelle piste, l'usinage ultrasonore rotatif. Le présent article nous permet tout d'abord de rappeler des notions nécessaires sur les ultrasons et sur leurs exploitations. Ensuite, nous allons décrire les conditions, les essais et les résultats de nos travaux sur l'usinage ultrasonore appliqués au bois

La structuration des connaissances au service de l'industrie 4.0 : Le cas du projet " SmartEmmma "

International audienceCet article discute les apports des méthodes de capitalisation et structuration des con-naissances pour l'amélioration de la performance dans le contexte de l'industrie du futur. Il présente aussi le projet ANR SmartEmma, questionne les problématiques de l'industrie de demain; entre autre, sont adressés les sujets de la capitalisation et de la structuration des connaissances pour la réutilisation dans des systèmes experts dans le cadre de l'usinagè a grande vitesse des pièces mécaniques aéronautiques, car il s'agit d'un point crucial pour améliorer la performance. Cet article commence par unétat de l'art sur les aspects de la gestion des connaissances dans le contexte de la quatrième révolution industrielle. Par la suite, la méthodologie de recherche sera détaillée ainsi que son application dans le cadre du projet SmartEmma

Cutting force model for machining of CFRP laminate with diamond abrasive cutter

The article presents a cutting force model for trimming operations of CFRP laminate with diamond abrasive cutters. Those tools are more and more encountered on industrial applications of CFRP trimming, due to their abrasion resistance and their low cost. Contrary to endmills, they consist of a large number of cutting grits, randomly distributed around the tool. To tackle the issue, a continuous model of tool engagement is proposed. Validity of the approach is verified. A mechanical model of cutting forces, adapted to CFRP laminate, is then presented. The evolution of specific cutting coefficient in relation to fibres orientation is investigated through a piecewise constant model. It leads to the proposal of a sine model for the specific cutting coefficients. The simulated forces are in good agreement with the experimental results of cutting tests, carried out in multidirectional CFRP laminate for different fibres orientation and widths of cut. Cutting mechanisms are finally discussed depending on fibres orientation

Classification contextuelle pour système d'aide à la décision pour machines-outils

International audienceDans le contexte général de l'Industrie 4.0, une entreprise de fabrication moderne dispose de nombreuses données numériques qui pourraient être utilisées pour rendre les machines-outils plus intelligentes et faciliter la prise de décision en matière de gestion opérationnelle. L'une des premières étapes de l'approche d'exploration de données est la sélection précise de données pertinentes. Pour ce faire, les données brutes doivent être classées dans différents groupes de contextes. Cet article présente une étude comparative d'algorithmes d'apprentissage automatique non-supervisé pour la classification contextuelle ; qui est utile pour un système d'aide à la décision pour machines-outils. Les vérifications par fouilles manuelles montrent que la méthode GMM permet d'obtenir de bons résultats de classification contextuelle, contrairement à celle des K-means. Mots-clés-UGV, Industrie 4.0, apprentissage non-supervisé

Batiprint3D and Yhnova : Open Innovation projects in the context of large scale

International audienc