3,077 research outputs found
Development of a Computationally Efficient Fabric Model for Optimization of Gripper Trajectories in Automated Composite Draping
An automated prepreg fabric draping system is being developed which consists
of an array of actuated grippers. It has the ability to pick up a fabric ply
and place it onto a double-curved mold surface. A previous research effort
based on a nonlinear Finite Element model showed that the movements of the
grippers should be chosen carefully to avoid misplacement and induce of
wrinkles in the draped configuration. Thus, the present study seeks to develop
a computationally efficient model of the mechanical behavior of a fabric based
on 2D catenaries which can be used for optimization of the gripper
trajectories. The model includes bending stiffness, large deflections, large
ply shear and a simple contact formulation. The model is found to be quick to
evaluate and gives very reasonable predictions of the displacement field
Systematic gripper arrangement for a handling device in lightweight production processes
Handhabungsgeräte sind ein integraler Bestandteil automatisierter
Produktionsprozesse. Dennoch werden sie in der Regel als nicht wertschöpfend
angesehen, weshalb ihre Planung und Projektierung mit geringem Zeit- und
Personalaufwand so effektiv wie möglich sein sollte. Gleichzeitig bleiben sie ein
wichtiger Teil der Prozesskette und müssen in diesem Zusammenhang bestimmte
Bedingungen erfüllen. Um ihre Funktionalität zu gewährleisten und wenig Zeit in die
Projektierung zu investieren, sind Handhabungsgeräte oft überdimensioniert.
Insbesondere bei flachen Teilen führt dies zu schweren Handhabungslösungen, bei
denen das Gewicht des Handhabungsobjekts und des Handhabungsgerätes in einem
Missverhältnis zueinander stehen.
Ziel der vorliegenden Arbeit ist es, die Projektierung von Handhabungsgeräten so weit
wie möglich zu automatisieren. Dieser Prozess wird am Beispiel der Prozesskette zur
Herstellung von Leichtbauteilen mit den Verfahren „sheet molding compound“ (SMC)
und „resin transfer molding“ (RTM) dargestellt.
In einem ersten Schritt wird ein modulares Handhabungsgerät entwickelt und
aufgebaut, das eine große Anzahl von Greiferanordnung ermöglicht. Mit diesem
Handhabungsgerät kann dann die resultierende Durchbiegung von flachen Bauteilen
mit verschiedenen Greiferanordnungen gemessen werden. Um sicherzustellen, dass
es nicht immer notwendig ist die Durchbiegungen zu messen, wird mit ABAQUS ein
Modell aufgebaut, das eine Simulation der Durchbiegung ermöglicht. Anhand dieses
Simulationsmodells wird eine Designlogik für die Anordnung der Greifer entwickelt.
Diese Designlogik arbeitet in zwei Schritten und basiert auf dem Ansatz des „growing
neural gas“ (GNG), das durch die Implementierung zusätzlicher Regeln an das Problem
angepasst wird. Zuerst wird eine erste Greiferkonfiguration basierend auf der
Geometrie des Objekts erstellt, die dann durch einen iterativen Prozess aus Simulation
und Anpassung verbessert wird. Da die Herstellung von Leichtbauteilen oft mehr als
nur einen Zuschnitt erfordert, werden am Ende systematisch verschiedene Lösungen
für die verschiedenen Zuschnitte zu einer Greiferanordnung zusammengefasst und ein
Verfahren gezeigt, wie dies ,mit dem zuvor entwickelten modularen Handhabungsgerät
realisiert, werden kann
Novel form-flexible handling and joining tool for automated preforming
The production rates of carbon fiber reinforced plastic (CFRP) parts are rising constantly which in turn drives research to bring a higher level of automation to the manufacturing processes of CFRP. Resin transfer molding (RTM), which is seen as a production method for high volumes, has been accelerated to a high degree. However, complex net-shape preforms are necessary for this process, which are widely manually manufactured. To face these challenges a new concept for the manufacturing of carbon fiber preforms with a form-flexible gripping, draping and joining end-effector is presented and discussed. Furthermore, this paper investigates the application of this concept, describes the initial build-up of a demonstrator, focusing on material selection and heating technology, and discusses test results with the prototype. This prototype already validates the feasibility of the proposed concept on the basis of a generic preform geometry. After a summary, this paper discusses future in-depth research concerning the concept and its application in more complex geometries. © 2015 by De Gruyter 2015
Form-flexible handling and joining technology (formhand) for the forming and assembly of limp materials
The assembly of limp, elastic or differently shaped objects poses a huge challenge which needs to be met by machine tools and the corresponding processes of handling, forming and joining. These processes are often carried out manually. This technological gap triggered the present work at the Technische Universität Braunschweig. A novel form-flexible handling tool (FormHand) is presented which focuses on the automation of these production steps taking into consideration the material behavior. The combination of the flexibility of both industrial robot and the FormHand end-effector allows for new processes appropriate for these materials. This article investigates the used materials of the granular filler and the cushion textile, the working states of FormHand and the use of online sensors for an automated process application
A Grasping-centered Analysis for Cloth Manipulation
Compliant and soft hands have gained a lot of attention in the past decade
because of their ability to adapt to the shape of the objects, increasing their
effectiveness for grasping. However, when it comes to grasping highly flexible
objects such as textiles, we face the dual problem: it is the object that will
adapt to the shape of the hand or gripper. In this context, the classic grasp
analysis or grasping taxonomies are not suitable for describing textile objects
grasps. This work proposes a novel definition of textile object grasps that
abstracts from the robotic embodiment or hand shape and recovers concepts from
the early neuroscience literature on hand prehension skills. This framework
enables us to identify what grasps have been used in literature until now to
perform robotic cloth manipulation, and allows for a precise definition of all
the tasks that have been tackled in terms of manipulation primitives based on
regrasps. In addition, we also review what grippers have been used. Our
analysis shows how the vast majority of cloth manipulations have relied only on
one type of grasp, and at the same time we identify several tasks that need
more variety of grasp types to be executed successfully. Our framework is
generic, provides a classification of cloth manipulation primitives and can
inspire gripper design and benchmark construction for cloth manipulation.Comment: 13 pages, 4 figures, 4 tables. Accepted for publication at IEEE
Transactions on Robotic
Textile Taxonomy and Classification Using Pulling and Twisting
Identification of textile properties is an important milestone toward
advanced robotic manipulation tasks that consider interaction with clothing
items such as assisted dressing, laundry folding, automated sewing, textile
recycling and reusing. Despite the abundance of work considering this class of
deformable objects, many open problems remain. These relate to the choice and
modelling of the sensory feedback as well as the control and planning of the
interaction and manipulation strategies. Most importantly, there is no
structured approach for studying and assessing different approaches that may
bridge the gap between the robotics community and textile production industry.
To this end, we outline a textile taxonomy considering fiber types and
production methods, commonly used in textile industry. We devise datasets
according to the taxonomy, and study how robotic actions, such as pulling and
twisting of the textile samples, can be used for the classification. We also
provide important insights from the perspective of visualization and
interpretability of the gathered data
FE tool for drape modelling and resin pocket prediction of fully embedded optical fiber sensor system
This work highlights some of the achievements obtained within the EU FP7 SmartFiber project, aiming to develop a fully embeddable optical fiber sensor system including the interrogator chip. The focus is on resolving issues holding back the industrial uptake of optical sensing technology. In a first section, the development of a placement head for automated lay-down of an optical sensor line (including the SmartFiber interrogator system) during composite manufacturing is discussed. In a second section, the attention is shifted to the occurrence of resin pockets surrounding inclusions such as the SmartFiber interrogator. A computationally efficient F.E. approach is presented capable of accurately predicting resin pocket geometries. Both small (i.e. optical fiber sensors) and large (i.e. the SmartFiber interrogator) inclusions are considered, and the F.E. predictions are validated with experimental observations
Glasgow's Stereo Image Database of Garments
To provide insight into cloth perception and manipulation with an active
binocular robotic vision system, we compiled a database of 80 stereo-pair
colour images with corresponding horizontal and vertical disparity maps and
mask annotations, for 3D garment point cloud rendering has been created and
released. The stereo-image garment database is part of research conducted under
the EU-FP7 Clothes Perception and Manipulation (CloPeMa) project and belongs to
a wider database collection released through CloPeMa (www.clopema.eu). This
database is based on 16 different off-the-shelve garments. Each garment has
been imaged in five different pose configurations on the project's binocular
robot head. A full copy of the database is made available for scientific
research only at https://sites.google.com/site/ugstereodatabase/.Comment: 7 pages, 6 figure, image databas
Automated Stamp Forming of Continuous Fiber Reinforced Thermoplastics for Complex Shell Geometries
This research describes the development of a fully automated forming process of continuous FRP to assemble a down scaled battery tray for a plug-in-hybrid automobile. The paper presents the results of forming experiments and a restraint approach to avoid wrinkling, an FEM forming simulation to detect the wrinkling behavior, shear effects and temperature trajectories for the consolidation at the end of the forming step, and a multi material gripper-system used for handling and preforming. The gripper system is capable of handling continuous FRP in different states and features a pneumatic stamp to pre-drape the heated organic sheet.BMBF/Open Hybrid LabFactor
Evaluation of design recommendations for the development of wheelchair rugby sports-wear
Currently, wheelchair rugby athletes face the challenges of playing the sport without specifically designed sports-wear kit. A few designs and recommendations have already been proposed by researchers but none have made it to market yet. The purpose of this study was to evaluate a set of design recommendations for the development of wheelchair rugby sports-wear. This was done so that the products to be created are developed in collaboration with their potential users, responding to their particular needs and requirements. The evaluation was done through an online survey, where the athletes were presented with a visual representation of the design recommendations. The results indicate that the people questioned agree with the majority of the proposed designs and would be happy to have these improvements made to their current sports-wear. The most criticised recommendations were for the gloves, as they are the most important part of the kit, so it is important that they are adequate and allow for a good performance
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