Augmented Reality in Manual Assembly Processes

in Kolla, Sri Sudha Vijay Keshav; Sanchez, Andre; Minoufekr, Meysam (Eds.) et al Augmented Reality in Manual Assembly Processes (2020, September 23)

Augmented Reality (AR) is a novel technology that projects virtual information on the real world environment. With the increased use of Industry 4.0 technologies in manufacturing, AR has gained momentum ... [more ▼]

Augmented Reality (AR) is a novel technology that projects virtual information on the real world environment. With the increased use of Industry 4.0 technologies in manufacturing, AR has gained momentum across various stages of product life cycle. AR can benefit production operators in many manufacturing tasks such as quality inspection, work instructions for manual assembly, maintenance, and in training. This research presents not only a typical architecture of an AR system but also both its software and hardware functions. The architecture is then applied to display virtual assembly instructions in the form of 3D animations on to the real world environment. The chosen assembly task in this research is to assemble a planetary gearbox system. The assembly instructions are displayed on a mobile device targeting a static tracker placed in the assembly environment. [less ▲]

Digitizing of Research and Teaching

Scientific Conference (2020, September 05)

The current Covid-19 crisis impacts all manufacturing areas and new processes are sought. This presentation provides the audience with three examples related to assembly work instructions, logistics data ... [more ▼]

The current Covid-19 crisis impacts all manufacturing areas and new processes are sought. This presentation provides the audience with three examples related to assembly work instructions, logistics data handling and manufacturing education, for which innovative ways to obtain access to context sensitive data based on digital tools are investigated. Augmented Reality (AR) and Virtual Reality (VR) facilitate access to relevant manufacturing information. In order to provide logistic warehouse workers with immediate access to shipping documents, to avoid paper print-outs, and to eliminate error-prone typing of information, critical information should be handled digitally and hands-free. To support logistic workers to efficiently document, register and trace receipt, storage or delivery of goods, the presented solution is built on hands-free digital tools with AR technology in commercially available smart glasses. Similarly, workers who execute complex assembly operations frequently require either assistance or support for the next assembly step. Depending on the context, relevant assembly process information is automatically displayed together with the environment in the AR smart glass. Thus, the operator is supported by the presented hands-free-tool to complete the next challenging tasks. Currently, teaching is being transferred from physical class-room teaching to remote or hybrid education. For this purpose, Virtual Reality (VR) provides a very welcome opportunity to complement in-presence teaching with exposure to examples of real manufacturing operations captured in videos of industrial case studies. Students apply learnings from theoretical classes to manufacturing case studies by identifying best practices and also recognizing waste. The presentation shares experience in teaching of lean methods based on AR technology to graduate engineering students. [less ▲]

Agent-based, hybrid control architecture for optimized and flexible production scheduling and control in remanufacturing

in Journal of Remanufacturing (2020), (2020),

Introduction: Motivated by high ecological and economical potentials and driven by new laws, remanufacturing is receiving increasing attention as a process that puts used products into “as good as new or ... [more ▼]

Introduction: Motivated by high ecological and economical potentials and driven by new laws, remanufacturing is receiving increasing attention as a process that puts used products into “as good as new or better” condition. Within this process, there are many challenges, which are unseen in manufacturing, such as the uncertainties resulting from unknown conditions of the used products. This places special demands on the control of the remanufacturing system (RS). Methodology: To handle these uncertainties an agent-based hybrid control architecture comprising centralized and decentralized components is presented. In the former, the scheduling takes place including the consideration of the use of automated guided vehicles (AGV) to realize flexible material handling within the RS. The scheduling of machines and AGVs is thereby considered simultaneously and not separately, as it is the case in currently available control systems. For the optimization of the simultaneous scheduling Constraint Programming (CP) is used. In the decentralized component, all participants within the RS will be networked as a cyber-physical system and controlled by respective agents. These agents can communicate with each other in order to find solutions. The architecture is implemented as a multi-agent system. Results: Simulation results, using benchmark instances, show that simultaneous scheduling results in a 19.7% reduction of the makespan. Furthermore, the CP-based approach delivers the best results, compared to other approaches for simultaneous scheduling, which are also achieved in a significantly shorter computing time. [less ▲]

Agentenbasierte, hybride Steuerungsarchitektur für cyberphysische Refabrikationssysteme

in Jäkel, Jens; Thiel, Robert (Eds.) Tagungsband AALE 2020 Automatisierung und Mensch-Technik-Interaktion (2020, March 05)

UNTERSUCHUNG DER METALLURGISCHEN PHASENBILDUNG UND DEREN EINFLUSS AUF DIE VERBINDUNGSEIGENSCHAFTEN SOWIE AUF DIE VERSAGENSURSACHEN VON LASERGESCHWEIßTEN HARTMETALL-STAHL-VERBUNDEN

Doctoral thesis (2020)

Laser beam welding of hard metal to steel offers multiple advantages regarding resource saving, mechanical strength of the joint and automation capability. The present work focuses on the fundamental ... [more ▼]

Laser beam welding of hard metal to steel offers multiple advantages regarding resource saving, mechanical strength of the joint and automation capability. The present work focuses on the fundamental research and development of the laser based welding process of tungsten carbide-cobalt hard metals with a tempering steel. Metallurgical analysis of the welding process showed that the formation of intermetallic and/or intermediate phases has a significant influence on the properties and mechanical strength of the dissimilar joint. The amount of molten hard metal in the steel melt bath plays a key role for the formation of the different phases. Therefore, a new parameter dy was defined, which correlates with the hard metal content in the melt pool. It is shown that for hard metals with 12 wt.% of cobalt binder, the phase transformation in the weld seam starts with a relative hard metal content of 10 vol.%. This threshold is dependent on the relative cobalt concentration in the hard metal. The tungsten carbide grain size has a low influence on the phase transformation in the weld seam. Steel melt pools with hard metal content lower than 10 vol.% show under metallographic observation a martensitic/bainitic microstructure. Simulation of the stress formation in the joint showed that due to the volume expansion of martensite during the transformation, tensile stress in the hard metal part was formed. Under shear load, these tensile stresses compensate with the induced compressive stresses and results an almost stress free interface. High shear strengths of the dissimilar joints are possible. A higher percentage of hard metal melting during the welding process increases the carbon and tungsten content in the melt bath. Consequently, the martensite start temperature decreases significantly. When the initiating temperature for martensite transformation falls under room temperature, the weld seam transforms into an austenitic microstructure. Because of the missing volume expansion during cooling of the weld seam volume, low stresses in the hard metal are generated. Under shear load of the joint area, high tensile stresses appear in the sintered part. These stress concentration decreases the shear strength of the weld and lead to premature failure. For the industrial use case, high mechanical strength and a robust manufacturing process is needed. Therefore, the laser welding process of hard metal to steel was optimized. The joint properties strongly depend on the weld bead geometry. Weld seams with x- or v-shaped profiles enable local concentrated metallurgical bonding of the sintered part to the steel sheet. Reduction of the horizontal focal distance of the laser beam to the interface increases the bonding ratio, but also intensifies the melting of the hard metal part and lead to the metallurgical transformation. By tilting a v-shape weld seam, it was possible to optimize the bonding behavior and to minimize the amount of liquefied hard metal in the melt bath. Hard metal with low amounts of binder showed a high temperature sensitivity. After laser welding of these grades, hot cracks were found in the sinter material. These cracks were formed due to the high stresses, which are generate during cooling of the dissimilar joint. Therefore, a laser based heat treatment process was developed and applied. With a defined pre- and post-heating of the joint area, the cooling rate was reduced significantly and the stresses in the hard metal part minimized. High shear strengths were the result. [less ▲]

Robotix-Academy Conference for Industrial Robotics (RACIR) 2019

Book published by Shaker - 3 (2020)

Robotix-Academy Conference for Industrial Robotics (RACIR) is held in University of Liège, Belgium, during June 05, 2019. The topics concerned by RACIR are: robot design, robot kinematics/dynamics/control ... [more ▼]

Robotix-Academy Conference for Industrial Robotics (RACIR) is held in University of Liège, Belgium, during June 05, 2019. The topics concerned by RACIR are: robot design, robot kinematics/dynamics/control, system integration, sensor/ actuator networks, distributed and cloud robotics, bio-inspired systems, service robots, robotics in automation, biomedical applications, autonomous vehicles (land, sea and air), robot perception, manipulation with multi-finger hands, micro/nano systems, sensor information, robot vision, multimodal interface and human-robot interaction. [less ▲]

Creation of an ISO Standard at the Example of Value Stream Management Method

in Jakobs, Kai (Ed.) Shaping the Future Through Standardization (2020)

The main objectives of this chapter are to elucidate the necessity of a standardized Value Stream Management (VSM) and to clarify how this standard can effectively increase corporate performance within ... [more ▼]

The main objectives of this chapter are to elucidate the necessity of a standardized Value Stream Management (VSM) and to clarify how this standard can effectively increase corporate performance within cross-enterprise supply chain networks (SCNs). VSM is an effective tool to collect, evaluate and continuously improve product and information flows within companies in a common and standardized manner. The findings of this chapter are not only valid for consistent product and information flows, but are representative for the relevance of standards in general. In a globalized economy, standards need to be generally accepted and valid for all countries. Thus, corporate or national standards, only have limited impact. The International Standardization Organization (ISO) provides the means to develop, negotiate and communicate standards, which are globally binding. This chapter shares the experience of ISO 22468 standard development within ISO/TC 154 WG7 and proves its applicability by an administrative use case. [less ▲]

Business analytics in manufacturing: Current trends, challenges and pathway to market leadership

in Operations Research Perspectives (2019)

Robotic Trajectory Tracking: Position- and Force-Control

Doctoral thesis (2019)

This thesis employs a bottom-up approach to develop robust and adaptive learning algorithms for trajectory tracking: position and torque control. In a first phase, the focus is put on the following of a ... [more ▼]

This thesis employs a bottom-up approach to develop robust and adaptive learning algorithms for trajectory tracking: position and torque control. In a first phase, the focus is put on the following of a freeform surface in a discontinuous manner. Next to resulting switching constraints, disturbances and uncertainties, the case of unknown robot models is addressed. In a second phase, once contact has been established between surface and end effector and the freeform path is followed, a desired force is applied. In order to react to changing circumstances, the manipulator needs to show the features of an intelligent agent, i.e. it needs to learn and adapt its behaviour based on a combination of a constant interaction with its environment and preprogramed goals or preferences. The robotic manipulator mimics the human behaviour based on bio-inspired algorithms. In this way it is taken advantage of the know-how and experience of human operators as their knowledge is translated in robot skills. A selection of promising concepts is explored, developed and combined to extend the application areas of robotic manipulators from monotonous, basic tasks in stiff environments to complex constrained processes. Conventional concepts (Sliding Mode Control, PID) are combined with bio-inspired learning (BELBIC, reinforcement based learning) for robust and adaptive control. Independence of robot parameters is guaranteed through approximated robot functions using a Neural Network with online update laws and model-free algorithms. The performance of the concepts is evaluated through simulations and experiments. In complex freeform trajectory tracking applications, excellent absolute mean position errors (<0.3 rad) are achieved. Position and torque control are combined in a parallel concept with minimized absolute mean torque errors (<0.1 Nm). [less ▲]

Laser overlap joining from copper to aluminum and analysis of failure zone

Scientific Conference (2019, June 26)

Joining of copper and aluminum sheets are very crucial for battery application. When joining from copper sheet, keyhole mode of welding is essential to overcome the reflectivity and melting threshold of ... [more ▼]

Joining of copper and aluminum sheets are very crucial for battery application. When joining from copper sheet, keyhole mode of welding is essential to overcome the reflectivity and melting threshold of copper. However, in dissimilar material interaction the resulting intermetallic (IMC) phases are brittle, which result in reduced performance.This paper analyses the joint with laser beam irradiated from the copper side (Cu on top). The idea is to distribute the intermetallic compounds inside the joint to obtain a ductile behavior. The zones of failure and the distribution of the intermetallic phase is studied. The microstructural analysis of the fusion zone and mechanical strength of the joint are presented. [less ▲]