Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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PowerGrasp: Development Aspects for Arm Support Systems

2022 , Goppold, J.-P. , Kuschan, J. , Schmidt, H. , Krüger, J.

Exoskeletons can support workers on physically demanding tasks, but in industry they lack of acceptance. This contribution gives an insight into design aspects for upper body exoskeletons, especially how active exoskeletons for industrial applications differ from military and medical use-cases. To overcome typical rigid exoskeleton problems, we suggest the use of modular soft-exosuit support systems and therefore checked different types of soft actuation principles for their eligibility for the use on upper body joints. Most promising approach is using two-layered actuators sting of robust fabric with embedded rubber tubes as pressure chambers. By inflating the tubes, it is possible to vary the stiffness of the chambers, which can be effectively used to generate assisting forces and moments at human joints (shoulder, elbow, wrist, finger).

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Simulating flow behaviour of wet particles within the immersed tumbling process

2021 , Uhlmann, E. , Polte, J. , Kuche, Y. , Landua, F.

For many production chains, it is mandatory to involve special finishing of the manufactured parts for the chipping of the edges as well as the polishing of surfaces. One commonly used method is the immersed tumbling process, where any workpiece is dragged through a particle filled container. In many cases, the immersed tumbling process operates in environments with added liquids, leading to changes in particle-tool interaction and general flow behaviour of the used particles. Whilst the discrete element method for simulating particles is mainly limited to dry particles, the used software ROCKY DEM from ESSS, Florianópolis, Brasil, comes with a built-in liquid-bridge model to simulate water-covered particles and granulate and furthermore an extension for system couplings with Ansys Fluent of the company ANSYS, INC., Canonsburg, Pennsylvania. The latter can be used to create from both software one three-phase-model with higher amounts of actually simulated water. In thi s study, small amounts of water were added to differently shaped particles using the build-in liquid-bridge model, to analyse and compare the particles flow characteristics in both, wet and dry environments. To gather significant information leading towards precise comparisons, the particles trajectories, velocities and resulting forces against the workpieces can be specifically observed and analysed, whilst this kind of process knowledge could previously never been taken into account without simulation.

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Concept for an actuated variable tool electrode for use in sinking EDM

2021 , Uhlmann, Eckart , Streckenbach, Jan , Thißen, Kai , Schulte Westhoff, Bela , Masoud, Abd Elkarim , Maas, Jürgen

Typically, a large number of individual tool electrodes has to be used in sinking electrical discharge machining (sinking EDM) to successfully machine a single workpiece. Due to non-uniform wear and insufficient flushing of the working gap electrode geometries have a significant effect on the process efficiency. This paper discusses the use of an actuated variable tool electrode for sinking EDM to reduce the number of required tool electrodes and to increase the overall process efficiency. A miniaturised linear actuator was developed to individually move electrode segments to form the target shape for the tool electrode. The coordinated actuation of bundled electrode segments introduces new methods for the active flushing within the working gap, which cannot be implemented in conventional sinking EDM. Intelligent sinking strategies can further improve process efficiency by creating and sinking sub-geometries into the workpiece offering improved flushing conditions compa red to the original geometry.

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Development of a Conceptual Understanding of the term Technological Capability

2021 , Hecklau, Fabian , Kidschun, Florian , Kohl, Holger , Hizal, Gamze Gül

The term "technological capability" has been studied for almost 40 years. It is an important component of technology strategy that contributes to the success and strengthening of organizations competitiveness. There are numerous attempts to define the term in the literature, but it is always used in different contexts. Thus, the definition of technological capability varies depending on the researcher's perspective and objectives. Therefore, the main objective of this research is to develop an own definition and interpretation of the term technological capability. To this end, an extensive literature review will be conducted to examine the basic concepts and management areas of technological capability and to analyze the individual definitions of the term. The subsequent goal is to derive an understanding of what technological capability is in terms of research and technology organizations.

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Time-Sensitive Networking over Metropolitan Area Networks for Remote Industrial Control

2021 , Tschöke, Simon , Lynker, Frederic , Buhr, Hauke , Schreiner, Florian , Willner, Alexander , Vick, Axel , Chemnitz, Moritz

The benefits of the currently evolving IEEE Time-Sensitive Networking (TSN) standard have already been globally recognized. Whereas the application of TSN in a LAN is currently widely and globally tested, TSN in a Metropolitan Area Network (MAN) has not been a major focus until now. The possible benefits of utilizing co-located Edge Clouds in order to support multiple urban production sites with industrial realtime applications open a wide range of new business models. Therefore, we have analyzed the feasibility of transparently using PROFINET over TSN via a Dense Wavelength Division Multiplex (DWDM) link, where a machine park is controlled remotely by an Edge-based virtual Programmable Logic Controller (vPLC). As a result, we are able to setup a TSN connection over a MAN with a one-way delay of about 156.5 J.ms and a jitter of about 12 ns. This work can be extended to allow for dynamically provisioned TSN flows and multi-path Frame Replication and Elimination (FRER) for distributed hard real-time machine control and adoption to Ultra-Reliable Low-Latency Communication (URLLC) 5G campus networks.

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Investigation of the gap bridgeability at high-power laser hybrid welding of plasma-cut thick mild steels with AC magnetic support

2021 , Üstündag, Ö. , Bakir, N. , Gumenyuk, A. , Rethmeier, M.

One of the challenges of the high-power hybrid laser welding of thick steels is the sensitivity of the process of the process to manufacturing tolerances. This usually leads to a time-consuming preparation of the welding edges, such as milling. The study deals with the influence of the edge quality of milled and plasma-cut steel made of S355J2 with a wall thickness of 20 mm on the laser hybrid welded seam quality. Furthermore, the gap bridgeability and the tolerances towards edge misalignment was investigated. An AC magnet was used as backing support to prevent sagging and positioned under the workpiece, to generate an upwards directed electromagnetic pressure. The profiles of the edges and the gap on the top and root side were measured using a digital camera. Single-pass laser hybrid welds of plasma-cut edges could be welded using a laser beam power of just 13.7 kW. A gap bridgeability up to 2 mm and misalignment of edges up to 2 mm could be achieved successful. Additionally, the independence of the cutting side and the welding side was shown, so that samples were welded to the opposite side to their cutting. For evaluation of internal defects or irregularities, X-ray images were carried out. Charpy impact strength tests were performed to determine the toughness of the welds.

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Effects on part density for a highly productive manufacturing of WC-Co via laser powder bed fusion

2021 , Polte, Julian , Neuwald, Tobias , Gordei, Anzhelika , Kersting, Robert , Uhlmann, Eckart

The additive manufacturing of parts made from difficult-to-weld materials through the usage of preheating temperatures of up to Î0 ⤠500 °C is enabled by newest L-PBF machine tools, such as the RenAM 500Q HT from the company RENISHAW PLC, Wottun-under-Edge, UK. This work aims to delevop processing parameters for the dense and crack-free manufacturing of tungsten-carbide cobalt (WC-Co) via this off-the-shelf machine tool. Therefore the laserpower and scanning speed were varied between 80 W ⤠PL ⤠350 W and 140 mm/s ⤠vS ⤠650 mm/s respectively. Furthermore the influence of a continuous and pulsed laser mode was analysed. A focus was set on the identification of parameters that enable a highly productive manufacturing while maintaining a high part density. A parameter set for relative density rel. > 94 % and a buildup rate v = 0.59 mm3/s was developed.

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Towards a Framework for Impact Assessment of Research & Technology Organisations

2021 , Kidschun, Florian , Hecklau, Fabian

Due to their ability to bridge the gap between knowledge created by basic research and market requirements, Research and Technology Organisations (RTOs) play a major role in countriesâ innovation systems. Their R&D results should lead to innovations, which in turn generate the economic output of public investment in research and development. Moreover, they should support the foundation of new companies and industrial innovations. RTOs can thus be seen as intermediaries between R&D and the industry, while they themselves constitute to a certain extent entrepreneurs and actors in applied R&D that focus on industrial and commercial application right from the start of their activities. Therewith, RTOs pursue to increase the competitiveness of the entire economy. With a growing demand for evaluating their actual contribution in national innovation systems, simply stating the goal of positive impact to stakeholders like governments, the public, investors etc. is not enough; its accomplishment needs to be proven by robust evidence. In this regard, the value of an impact assessment is determined by the strength of the evidence produced and the credibility of the evaluation. RTOâs research activities and their impacts are diverse in nature and occur across many sectors of the economy. To gain transparent insights into relevant and comprehensive performance metrics showing the impact of RTOs from a micro- and macroeconomic perspective, impacts are only appropriate for evaluation if a causal relationship can be drawn back to their origin. While some impacts are primarily economic and suitable for quantitative analysis, others have to be evaluated qualitatively. Regardless of its type, each impact needs to be assessed within a common framework to enable a comprehensive understanding of RTO's impact. Within this contribution, an impact assessment framework is established with the aim to enable the identification of causal relationships between impacts and their origin.

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How Pedestrians Perceive Autonomous Buses: Evaluating Visual Signals

2021 , Brandenburg, Elisabeth , Kozachek, Diana , Konkol, Kathrin , Woelfel, Christiane , Geiger, Andreas , Stark, Rainer

With the deployment of autonomous buses, sophisticated technological systems are entering our daily lives and their signals are becoming a crucial factor in human-machine interaction. The successful implementation of visual signals requires a well-researched human-centred design as a key component for the new transportation system. The autonomous vehicle we investigated in this study uses a variety of these: Icons, LED panels and text. We conducted a user study with 45 participants in a virtual reality environment in which four recurring communication scenarios between an autonomous driving bus and its potential passengers had to be correctly interpreted. For our four scenarios, efficiency and comprehension of each visual signal combination was measured to evaluate performance on different types of visual information. The results show that new visualization concepts such as LED panels lead to highly variable efficiency and comprehension, while text or icons were well ac cepted. In summary, the authors of this paper present the most efficient combinations of visual signals for four reality scenarios.

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Service Modelling Language Applied for Hyper Connected Ecosystem

2021 , Jäkel, Frank-Walter , Zelm, Martin , Chen, David

The paper elaborates the application of service modelling language for hyper-connected ecosystems. A specific target is to demonstrate the use of ISO 19440 standard together with a set of specialized service modelling constructs developed in the scope of CEN TC310/WG1. It presents a conceptual use case to model a 'Matching Service' and the service system required to provide the Matching Service in a service ecosystem. The purpose of this study is to test and demonstrate the use of a service modelling language related to ISO19440:2020 to describe in a formal and systematic way a service and its needed service system at business level for communication and validation. The paper first presents the motivation of the study and recalls related works. The service modelling language and the background of this work are discussed. The Matching service use case will be presented in detail and the concluding summary as well as some outlooks are given at the end of the paper.

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