Experimental External Force Estimation Using a Non-Linear Observer for 6 axes Flexible-Joint Industrial Manipulators

This paper proposes a non-linear observer to estimate not only the state (position and velocity) of links but also the external forces exerted by the robot during Friction Stir Welding (FSW) processes. The difficulty of performing this process with a robot lies in its lack of rigidity. In order to ensure a better tracking performance, the data such as real positions, velocities of links and external forces are required. However, those variations are not always measured in most industrial robots. Therefore, in this study, an observer is proposed to reconstruct those necessary parameters by using only measurements of motor side. The proposed observer is carried out on a 6 DOF flexible-joint industrial manipulator used in a FSW process.ANR-2010-SEGI-003-01-COROUSSO, French National Agenc

Optimal workplacement for robotic friction stir welding task

Robotic manipulators are widely used in industry for welding processes. Inadequate joint stiffness in the manipulators often limits their use for high quality welding operations because of the deformation errors produced during the process. As a matter of fact, welding quality deteriorates with decreasing joint stiffness. This paper presents an approach to determine an optimal workspace of operation by minimizing the lateral deflection errors in position and orientation of the end effector during Friction Stir Welding. This has been done by estimating the errors in position and orientation of the end effector, also the point of contact with work piece which directly affects welding quality, when it experiences a wrench during welding operation. The technique was applied to an elastodynamic model of a 6 DOF manipulator with different path constraints for welding process to achieve optimal task placement. In a nutshell, optimal starting position or an optimal direction of motion for best welding quality can be precisely computed or even both together can be calculated but with numerical complexity.ANR COROUSS

Modeling of high speed friction stir spot welding using a lagrangian finite element approach

Friction stir spot welding (FSSW) has been shown to be capable of joining steels of very high strength, while also being very flexible in terms of controlling the heat of welding and the resulting microstructure of the joint. This makes FSSW a potential alternative to resistance spot welding (RSW) if tool life is sufficiently high, and if machine spindle loads are sufficiently low so that the process can be implemented on an industrial robot. Robots for spot welding can typically sustain vertical loads of about 8kN, but FSSW at tool speeds of less than 3000 rpm cause loads that are too high, in the range of 11-14 kN. Therefore, in the current work tool speeds of 3000 rpm and higher were employed, in order to generate heat more quickly and to reduce welding loads to acceptable levels. The FSSW process was modeled using a finite element approach with the Forge® software package. An updated Lagrangian scheme with explicit time integration was employed to model the flow of the sheet material, subjected to boundary conditions of a rotating tool and a fixed backing plate [3]. The modeling approach can be described as two-dimensional, axisymmetric, but with an aspect of three dimensions in terms of thermal boundary conditions. Material flow was calculated from a velocity field which was two dimensional, but heat generated by friction was computed using a virtual rotational velocity component from the tool surface. An isotropic, viscoplastic Norton-Hoff law was used to model the evolution of material flow stress as a function of strain, strain rate, and temperature. The model predicted welding temperatures and the movement of the joint interface with reasonable accuracy for the welding of a dual phase 980 steel

A Novel Approach for Simplification of Industrial Robot Dynamic Model Using Interval Method

This paper proposes a new approach to simplify the dynamic model of industrial robot by means of interval method. Due to strong nonlinearities, some components of robot dynamic model such as the inertia matrix and the vector of centrifugal, Coriolis and gravitational torques, are very complicated for real-time control of industrial robots. Thus, a simplification algorithm is presented in this study in order to reduce the computation time and memory occupation. More importantly, this simplification is suitable for arbitrary trajectories in whole robot workspace. Furthermore, the method devotes to finding negligible inertia parameters, which is useful for robot model identification. A simulation has been carried out on a test trajectory using a 6-DOF industrial robot model, and the results have shown good performance and effectiveness of this method.ANR COROUSS

Mass Production Processes

It is always hard to set manufacturing systems to produce large quantities of standardized parts. Controlling these mass production lines needs deep knowledge, hard experience, and the required related tools as well. The use of modern methods and techniques to produce a large quantity of products within productive manufacturing processes provides improvements in manufacturing costs and product quality. In order to serve these purposes, this book aims to reflect on the advanced manufacturing systems of different alloys in production with related components and automation technologies. Additionally, it focuses on mass production processes designed according to Industry 4.0 considering different kinds of quality and improvement works in mass production systems for high productive and sustainable manufacturing. This book may be interesting to researchers, industrial employees, or any other partners who work for better quality manufacturing at any stage of the mass production processes

A Review of Orbital Friction Stir Welding

Funding Information: The authors acknowledge the Portuguese Agência Nacional de Inovação (ANI), trough the project SI I&DT (PROJETOS MOBILIZADORES), Nº 024534-“INFANTE-Microssatélite para Vigilância Marítima, Observação da Terra e IoT no contexto de constelações”, co-financed by PORTUGAL2020, through Fundo Europeu de Desenvolvimento Regional (FEDER). Authors acknowledge the Portuguese Fundação para a Ciência e a Tecnologia (FCT–MCTES) for its financial support via the project UID/EMS/00667/2019 (UNIDEMI). Authors acknowledge funding by national funds from FCT-Fundação para a Ciência e a Tecnologia, I.P., in the scope of the projects LA/P/0037/2020, UIDP/50025/2020 and UIDB/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication–i3N. Publisher Copyright: © 2023 by the authors.Friction stir welding is a solid-state joining process widely used in several industrial applications. One of its variants, orbital friction stir welding, is of key importance in fundamental industries such as oil and gas and aerospace. For orbital friction stir welding, there is a need to develop not only new process parameters but also tools and ancillary mechanisms that can ensure sound, high-performing joints are obtained. This review assesses the current state of orbital friction stir welding, highlighting several key aspects related to this technology.publishersversionpublishe

Démarche pour le choix et/ou la conception d’un moyen de soudage par FSW

Les travaux de recherches présentés concernent l'industrialisation du procédé de soudage par friction malaxage, également appelé Friction Stir Welding (FSW). L'objectif est de fournir des outils aux industriels pour choisir et qualifier une machine pour leurs applications de FSW. Cet article présente une méthodologie pour qualifier et / ou concevoir les moyens de soudage adaptés à une application donnée. La démarche de qualification repose sur l’étude géométrique des pièces et sur l’analyse des actions mécaniques transmises par l’outil au travers les domaines de soudabilités. La démarche globale est présentée à l’aide du formalisme IDEF0.The objective of the presented research work is the industrialization of the friction stir welding process in order to provide tools to industrials to select and qualify a means of production for their FSW applications. This paper presents a methodology to determine the Friction Stir Welding means of production adequate to an application. The methodology is based on the analysis of the workpiece geometries and the analysis of the process forces and torqus generated during welding through the determination of the process windows. In this paper, the means of production determination method is presented thanks the IDEF0 formalism