Digital Twin for Variation Management: A General Framework and Identification of Industrial Challenges Related to the Implementation

Digital twins have gained a lot of interest in recent years. This paper presents a survey among researchers and engineers with expertise in variation management confirming the interest of digital twins in this area. The survey shows, however, a gap between future research interest in academia and industry, identifying a larger need in industry. This indicates that there are some barriers in the industry to overcome before the benefits of a digital twin for variation management and geometry assurance can be fully capitalized on in an industrial context. To identify those barriers and challenges, an extensive interview study with engineers from eight different companies in the manufacturing sectors was accomplished. The analysis identifies industrial challenges in the areas of system-level, simulation working process, management issues, and education. One of the main challenges is to keep the 3D models fully updated, including keeping track of changes during the product development process and also feedback changes during full production to the development engineers. This is a part of what is called the digital thread, which is also addressed in this paper

Tolerancing Informatics: Towards Automatic Tolerancing Information Processing in Geometrical Variations Management

The management of geometrical variations throughout the product life cycle strongly relies on the gathering, processing, sharing and dissemination of tolerancing information and knowledge. While today, this is performed with many manual interventions, new means for automatic information processing are required in future geometrical variations management to make full use of new digitalization paradigms, such as industry 4.0 and digital twins. To achieve this, the paper proposes the term tolerancing informatics and investigates new concepts and means for automatic information processing, novel information sharing workflows as well as the integration of tools for next generation geometrical variations management. In this regard, the main aim of the paper is to structure existing tolerancing informatics workflows as well as to derive future research potentials and challenges in this domain. The novelty of the paper can be found in providing a comprehensive overview of tolerancing informatics as an important enabler for future geometrical variations management

Challenges and Potentials of Digital Twins and Industry 4.0 in Product Design and Production for High Performance Products

Digital twins offer great opportunities in various domains of the product engineering process. However, current approaches to the use of digital twins only focus on different separated disciplines. In contrast to that, it is expected that the holistic use of digital twin models in product development and production will dominate future product generations, because they allow to create high-performance products competitively. This paper explores important challenges and future potentials of digital twins and Industry 4.0 for the seamless integration of product specification and production. In this regard, approaches of linking digital twins to other domains open up new possibilities in tolerance allocation and production integration. Thereby, the most efficient product specifications in technical and economic terms are achieved for the manufacturer. In addition, the connectivity of Industry 4.0 broadens the scope and enables the evaluation of alternative approaches in production planning and control. Approaches at the organizational level, product functions with specifications beyond the technological limits and production control strategies (e.g. order dispatching) ensure high performance operations. Simulations with a digital production twin with integrated digital product twin allow early estimations even before the actual ramp-up of the product. The future challenge addressed in this paper is to define a consistent framework for the holistic use of digital twins in the entire product development process, which requires the integration of product designers and production planner concepts

Konzept zur Verbesserung des realitätsgetreuen, visuellen Erlebens in virtuellen Umgebungen durch Eye-Tracking

Ein positives Nutzungserlebnis (engl. User Experience) ist einer der Schlüsselaspekte erfolgreicher Produkte und damit auch eine der Grundlagen für den wirtschaftlichen Erfolg eines Unternehmens. Ergonomische Bedienbarkeit und ansprechende Gestaltung des Produkts haben hierauf einen starken Einfluss (Schröppel & Wartzack, 2018). Entwickler und Designer versuchen deshalb, dieses Erlebnis bereits in einer möglichst frühen Phase des Produktentwicklungsprozesses zu erfassen und zu bewerten. Ein in der Automobilbranche erfolgreich eingesetztes Werkzeug zur Bewertung des Nutzungserlebnisses ist der Prototypenbau. Der Einsatz von solchen prototypischen Realaufbauten ist allerdings mit einem hohen finanziellen und vor allem mit einem hohen zeitlichen Aufwand verbunden. Deshalb werden diese meistens erst relativ spät im Produktentwicklungsprozess verwendet. Im Sinne des „Frontloadings“ wäre es vielmehr wünschenswert und sinnvoll, früh zur Verfügung stehende, digitale Modelle für die Bewertung des Nutzererlebnisses zu verwenden. Damit könnten bereits in einer frühen Phase des Produktentwicklungsprozesses Erkenntnisse über das Nutzungserlebnis unterschiedlicher Konzepte in die Entwicklung des Produkts einfließen. [... aus Punkt 1

From tolerance allocation to tolerance-cost optimization: a comprehensive literature review

It is widely acknowledged that the allocation of part tolerances is a highly responsible task due to the complex repercussions on both product quality and cost. As a consequence, since its beginnings in the 1960s, least-cost tolerance allocation using optimization techniques, i.e. tolerance-cost optimization, was continuously in focus of numerous research activities. Nowadays, increasing cost and quality pressure, availability of real manufacturing data driven by Industry 4.0 technologies, and rising computational power result in a continuously growing interest in tolerance-cost optimization in both research and industry. However, inconsistent terminology and the lack of a classification of the various relevant aspects is an obstacle for the application of tolerance-cost optimization approaches. There is no literature comprehensively and clearly summarizing the current state of the art and illustrating the relevant key aspects. Motivated to overcome this drawback, this article provides a comprehensive as well as detailed overview of the broad research field in tolerance-cost optimization for both beginners and experts. To facilitate the first steps for readers who are less familiar with the topic, the paper initially outlines the fundamentals of tolerance-cost optimization including its basic idea, elementary terminology and mathematical formulation. These fundamentals serve as a basis for a subsequent detailed discussion of the key elements with focus on the different characteristics concerning the optimization problem, tolerance-cost model, technical system model and the tolerance analysis model. These aspects are gathered and summarized in a structured mind map, which equips the reader with a comprehensive graphical overview of all the various facets and aspects of tolerance-cost optimization. Beside this, the paper gives a retrospect of the past fifty years of research in tolerance cost-optimization, considering 290 relevant publications. Based thereon, current issues and future research needs in tolerance-cost optimization were identified

Comparative evaluation of WIMP and immersive natural finger interaction: a user study on CAD assembly modeling

Virtual and augmented reality allows the utilization of natural user interfaces, such as realistic finger interaction, even for purposes that were previously dominated by the WIMP paradigm. This new form of interaction is particularly suitable for applications involving manipulation tasks in 3D space, such as CAD assembly modeling. The objective of this paper is to evaluate the suitability of natural interaction for CAD assembly modeling in virtual reality. An advantage of the natural interaction compared to the conventional operation by computer mouse would indicate development potential for user interfaces of current CAD applications. Our approach bases on two main elements. Firstly, a novel natural user interface for realistic finger interaction enables the user to interact with virtual objects similar to physical ones. Secondly, an algorithm automatically detects constraints between CAD components based solely on their geometry and spatial location. In order to prove the usability of the natural CAD assembly modeling approach in comparison with the assembly procedure in current WIMP operated CAD software, we present a comparative user study. Results show that the VR method including natural finger interaction significantly outperforms the desktop-based CAD application in terms of efficiency and ease of use

Early Robust Design—Its Effect on Parameter and Tolerance Optimization

Featured Application This paper emphasizes the important role of early robust design for optimal parameter and tolerance design. The theoretically discussed effects on parameter and tolerance optimization are supplemented by an illustrative case study showing the benefits of a robust product concept. Abstract The development of complex products with high quality in dynamic markets requires appropriate robust design and tolerancing workflows supporting the entire product development process. Despite the large number of methods and tools available for designers and tolerance engineers, there are hardly any consistent approaches that are applicable throughout all development stages. This is mainly due to the break between the primarily qualitative approaches for the concept stage and the quantitative parameter and tolerance design activities in subsequent stages. Motivated by this, this paper bridges the gap between these two different views by contrasting the used terminology and methods. Moreover, it studies the effects of early robust design decisions with a focus on Suh’s Axiomatic Design axioms on later parameter and tolerance optimization. Since most robust design activities in concept design can be ascribed to these axioms, this allows reliable statements about the specific benefits of early robust design decisions on the entire process considering variation in product development for the first time. The presented effects on the optimization of nominal design parameters and their tolerance values are shown by means of a case study based on ski bindings

Statistical Tolerance Analysis of 3D-Printed Non-Assembly Mechanisms in Motion Using Empirical Predictive Models

Fused Deposition Modelling (FDM) enables the fabrication of entire non-assembly mechanisms within a single process step, making previously required assembly steps dispensable. Besides the advantages of FDM, the manufacturing of these mechanisms implies some shortcomings such as comparatively large joint clearances and geometric deviations depending on machine-specific process parameters. The current state-of-the-art concerning statistical tolerance analysis lacks in providing suitable methods for the consideration of these shortcomings, especially for 3D-printed mechanisms. Therefore, this contribution presents a novel methodology for ensuring the functionality of fully functional non-assembly mechanisms in motion by means of a statistical tolerance analysis considering geometric deviations and joint clearance. The process parameters and hence the geometric deviations are considered in terms of empirical predictive models using machine learning (ML) algorithms, which are implemented in the tolerance analysis for an early estimation of tolerances and resulting joint clearances. Missing information concerning the motion behaviour of the clearance affected joints are derived by a multi-body-simulation (MBS). The exemplarily application of the methodology to a planar 8-bar mechanism shows its applicability and benefits. The presented methodology allows evaluation of the design and the chosen process parameters of 3D-printed non-assembly mechanisms through a process-oriented tolerance analysis to fully exploit the potential of Additive Manufacturing (AM) in this field along with its ambition: ‘Print first time right’

Ausarbeitungsleitfaden für Nutzerstudien zur Evaluation von XR-Interfaces in der Produktentwicklung

Technologien der erweiterten Realität (extended reality, XR) finden im gesamten Produktentwicklungsprozess Anwendung. Insbesondere Systeme zur aktiven Erzeugung und Veränderung digitaler Produktdaten bieten noch viel Potential. Die Erforschung und Entwicklung dieser immersiven Interfaces beruht maßgeblich auf der Evaluation durch Nutzerstudien, denn nur so kann die Einsatztauglichkeit der Mensch-Maschine-Schnittstellen seriös beurteilt und verglichen werden. Bei der Konzeptionierung und Durchführung dieser Nutzerstudien gibt es viel zu beachten. In dieser Arbeit wird ein Leitfaden für das Design von Evaluationen von XR Interfaces für die Produktentwicklung präsentiert. Zu Beginn müssen die Fragestellungen festgelegt werden, welche die Studie beantworten soll. Ausgehend von diesen müssen die zu testenden Versuchsbedingungen, die gestellten Aufgaben, die aufgenommen Metriken, die gewählten Probanden und der geplante Ablauf festgelegt werden. Zusätzlich zu der allgemeinen Darlegung wird das Vorgehen anhand eines Fallbeispiels angewandt. Die Gestaltung einer Nutzerstudie zur Evaluation der Usability und Eignung eines neuartigen Virtual Reality Interfaces zur natürlichen Gestaltung von Vorentwürfen wird vorgestellt

Integration of robust and tolerance design in early stages of the product development process

Due to the tightening of requirements and the increasing complexity of products, robust design becomes more and more important in the context of a straightforward product development. Although various robust design methods have been evolved to support the design of products that are less sensitive to variations, these methods are not sufficiently integrated into early stages of the product development process. This is mainly due to the lack of concrete product data necessary for robustness evaluation and tolerance specification. For this reason, it is still unclear to product development engineers when and how to apply existing approaches for enhancing the robustness of products. Therefore, this paper describes a holistic methodology that supports the designer in developing a robust product layout including an initial, validated tolerance specification based on the functional requirements. The proposed framework focuses on the close linkage of robust design activities with product data along the product development process and demonstrates the resulting benefits of an early consideration of variations and tolerances. In addition to the proper choice of robust product concepts and their corresponding spatial arrangement in the product structure, the approach allows a conceptual tolerance specification and the subsequent CAD-based analysis based on the preliminary design. Thus, the proposed approach aims to reduce iterations in the conventional tolerancing. To demonstrate the process, the methodology is applied to an electric window regulator