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See detailOptimierung und Charakterisierung einer mittels Laserstrahl gefügten Verbindung zwischen Aluminium und Polyamid 6.6
Lamberti, Christian UL

Doctoral thesis (2018)

The creation of strong joints between dissimilar materials and in particular between polymers and metals is one of the most often discussed topics in the fields of automotive, aerospace and transportation ... [more ▼]

The creation of strong joints between dissimilar materials and in particular between polymers and metals is one of the most often discussed topics in the fields of automotive, aerospace and transportation. Especially the combination of polyamide and aluminum is of highest interest, due to their market share as construction materials. New joining concepts are anticipated to deliver strong, durable and resource efficient structural components that are ideally suited for lightweight designs. However, current research activities have shown that the highly distinct material properties of these materials pose enormous challenges on the creation of hybrid structures. The cause that potentially enables the connection between the aluminum surface and the polymer is still not fully understood. The research objective of the presented work, therefore is, on the one hand, to create an optimal joint between aluminum and polyamide 6.6 using a laser beam to reach high shear strength for an industrial application. On the other hand, the presented work seeks to deliver a substantial contribution to furtherly understand the interaction between the polymer and the metal surface during the thermal joining. A laser-based joining method was developed that enables the researchers to overcome limitations of conventional processes, that is minimizing space requirements, making the application of additional gaskets obsolete, reaching high strength, saving weight and reducing processing time. The effectiveness of different surface pre-treatments has been studied, and the described optimization of this method has lead to an increase of the shear strength of the joints by more than 100 %. Laser ablation and the hydrothermal treatment of the metallic surface, before the joining operation, lead to the highest joint strength. The surface pre-treatment method of laser ablation delivered to transfer the gathered insights and experience from the laboratory to the industrial scale, due to its repeatability and reproducibility. The experiment mentioned above includes the use of production materials, such as aluminum with a higher sheet thickness of up to 1.48 mm and glass fiber reinforced polymer. Shear strength of 40 MPa was reached in quasi-static single lap shear tests. During dynamic testing, samples maintained 63 % of static breaking load after one million cycles. The hydrothermal treatment of the aluminum surface leads to a lower surface roughness of Ra = 1.58 µm in average as opposed to 4.90 µm after laser ablation. Due to the lower roughness values, the first-mentioned method was chosen to study the interaction. An XPS-analysis revealed a strong influence of the surface pre-treatment method on the chemical composition of the metal surface, which becomes noticeable by hydroxylation of the surface layer and is expressed by the oxide ratio (O/Al) and hydroxide ratio (OH/O). A high O/Al ratio of 2.36 and an OH/O ratio of 0.63 after the hydrothermal treatment is showing a strong increase of the amount of hydroxide in direct comparison to values of 35 % and 36 % of OH/O ratio after ethanol and hexane cleaning respectively. The question, as to which extent the presence of such hydroxide structures at the boundary layer of the aluminum influence the interaction between the metal surface and the polymer, was a subject matter of an additional FT-IR analysis. In case of the infrared spectra from thin polymer films on the hydrothermally treated surface, clear indications of interaction are visible. In direct comparison to the infrared spectra from polymer films on either ethanol or hexane cleaned surfaces, this interaction seems to increase nearby of the interface further. The interaction mentioned above appears at the carbonyl band and amine band as a shift of 4 cm-1 and 8 cm-1 and an increase of the full width at half maximum by 35 % respectively 40 %. Additional strong differences are visible at the molecule vibrations below 1,200 cm-1, which are typically assigned to both crystalline phases and amorphous phases of the polyamide. In case of the hydrothermal treatment, collected data indicates a polymorphous state inside the polymer films, which seems to become increasingly disordered close to the interface. On the contrary, spectra from the polymer films on ethanol and hexane pre-treated substrates show only marginal changes. Methods are proposed to build upon the results described in this work and refine distinct signs of the interaction. [less ▲]

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See detailLessons from social network analysis to Industry 4.0
Omar, Yamila UL; Minoufekr, Meysam UL; Plapper, Peter UL

in Manufacturing Letters (2018), 15B

With the advent of Industry 4.0, a growing number of sensors within modern production lines generate high volumes of data. This data can be used to optimize the manufacturing industry in terms of complex ... [more ▼]

With the advent of Industry 4.0, a growing number of sensors within modern production lines generate high volumes of data. This data can be used to optimize the manufacturing industry in terms of complex network topology metrics commonly used in the analysis of social and communication networks. In this work, several such metrics are presented along with their appropriate interpretation in the field of manufacturing. Furthermore, the assumptions under which such metrics are defined are assessed in order to determine their suitability. Finally, their potential application to identify performance limiting resources, allocate maintenance resources and guarantee quality assurance are discussed. [less ▲]

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See detailAluminum pretreatment by a laser ablation process: influence of processing parameters on the joint strength of laser welded aluminum – polyamide assemblies
Al Sayyad, Adham UL; Bardon, Julien; Hirchenhahn, Pierre et al

in Procedia CIRP (2018)

Laser welding of metal – polymer assemblies is an innovative bonding process. It was already demonstrated that laser surface pretreatments of aluminum (Al), prior to laser welding with a polymer, impacts ... [more ▼]

Laser welding of metal – polymer assemblies is an innovative bonding process. It was already demonstrated that laser surface pretreatments of aluminum (Al), prior to laser welding with a polymer, impacts joints strength. This work adopts a design of experiments (DoE) approach to investigate the influence of several Al laser ablation parameters on joint strength of laser welded Al – polyamide (PA6.6) assemblies. Significant parameters were highlighted, process window was outlined, and optimal parameters were identified. After assembly failure, the joint area was evaluated using optical microscopy. Depending on the laser ablation parameters, the joint area can be enhanced resulting in a significant increase in the corresponding bearable shear load. [less ▲]

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See detailLearning-While Controlling RBF-NN for Robot Dynamics Approximation in Neuro-Inspired Control of Switched Nonlinear Systems
Klecker, Sophie UL; Hichri, Bassem UL; Plapper, Peter UL

in Artificial Neural Networks and Machine Learning; ICANN 2018 part 3 (2018)

Radial Basis Function-Neural Networks are well-established function approximators. This paper presents an adaptive Gaussian RBF-NN with an extended learning-while controlling behaviour. The weights ... [more ▼]

Radial Basis Function-Neural Networks are well-established function approximators. This paper presents an adaptive Gaussian RBF-NN with an extended learning-while controlling behaviour. The weights, function centres and widths are updated online based on a sliding mode control element. In this way, the need for fixing parameters a priori is overcome and the network is able to adapt to dynamically changing systems. The aim of this work is to present an extended adaptive neuro-controller for trajectory tracking of serial robots with unknown dynamics. The adaptive RBF-NN is used to approximate the unknown robot manipulator dynamics-function. It is combined with a conventional controller and a bio-inpsired extension for the control of a robot in the presence of switching constraints and discontinuous inputs. Its learned goal-directed output results from the complementary action of an actuator, A, and a prventer, P. The trigger is an incentive, I, based on the weighted perception of the enviornment. The concept is validated through simulations and implementation on a KUKA LWR4-robot. [less ▲]

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See detailRecent Progress Toward Intelligent Robot Assistants for Non-Destructive Disassembly
Jungbluth, Jan UL; Gerke, Wolfgang; Plapper, Peter UL

in Müller, Rainer; Plapper, Peter; Brüls, Olivier (Eds.) et al Robotix-Academy Conference for Industrial Robotics (RACIR) 2018 (2018)

One key to successful and fluent human-robot collaboration in disassembly processes is equipping the robot systems with greater autonomy and intelligence. In this paper, we present our progress in ... [more ▼]

One key to successful and fluent human-robot collaboration in disassembly processes is equipping the robot systems with greater autonomy and intelligence. In this paper, we present our progress in developing such an intelligent robot assistant system. We present the multi-agent control architecture we developed and describe its technical implementation. Our control approach relies on two types of knowledge models: product and process models. The product model describes the structure of the product to be dismantled through a description of the parts involved and the connections between them. A connection type-related process model describes which agents and objects participate in the disassembly process and which methods of human-robot cooperation or collaboration are most useful. When supplied with a product model and a goal definition, our robotic assistant can automatically generate a partially ordered disassembly task sequence. For each disassembly task, the user can choose one of the divisions of labor defined in the process model. Using the process model, through perception and deliberation, the control system can both execute actions and coordinate and synchronize the actions of human and machine. This approach allows the system to be more autonomous when providing assistance to human coworkers in complex and one-piece disassembly processes. [less ▲]

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See detailCombining Virtual and Robot Assistants - A Case Study about Integrating Amazon's Alexa as a Voice Interface in Robotics
Jungbluth, Jan UL; Krieger, Rolf; Gerke, Wolfgang et al

in Müller, Rainer; Plapper, Peter; Brüls, Oliver (Eds.) et al Robotix-Academy Conference for Industrial Robotics (RACIR) 2018 (2018)

Virtual assistants such as Alexa, Siri, Cortana and Google Assistant increasingly find ways to enter our homes and everyday lives, where they serve as powerful human-machine interfaces to control devices ... [more ▼]

Virtual assistants such as Alexa, Siri, Cortana and Google Assistant increasingly find ways to enter our homes and everyday lives, where they serve as powerful human-machine interfaces to control devices through natural language. In this work, we explore the use of virtual assistants to control single components within an intelligent industrial robot assistant system for disassembly applications. Following a short introduction and an overview of commercially available virtual assistants, we present our system architecture, which integrates Amazon's Alexa through an Echo Dot device. Utilizing the Alexa Skill Kit, we build a voice user interface that contains dialogs to control various device functions and assistive system behaviors. By connecting Alexa Voice Service with Amazon’s Lambda and IoT web services, we can parametrize machine commands depending on the user's voice input and, through a Raspberry Pi, which routes messages between the internet and decoupled machine network, send them to the devices within the intelligent robot assistance system. With the reversed communication flow, we can update and store the current state of the devices in the Amazon Web Services IoT Shadow. Utilizing the IoT Shadow, we are able to inform the user upon request about the current state of the devices by synthesize speech with the Alexa Voice Services and vocalize it through the Echo Dot. One implemented assistive system behavior and the related dialog to activate the behavior is further explained in this work. In the conclusion, we address our gathered positive and negative experience to date. [less ▲]

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See detailContinuous Improvement of complex process flows by means of StreaM
Oberhausen, Christof UL; Minoufekr, Meysam UL; Plapper, Peter UL

Presentation (2017, December 11)

In numerous sectors and industries worldwide, there is a trend towards an intercompany and often international division of value creation and related work tasks. To overcome the challenges of complex ... [more ▼]

In numerous sectors and industries worldwide, there is a trend towards an intercompany and often international division of value creation and related work tasks. To overcome the challenges of complex cross-enterprise supply chain networks, innovative approaches to visualize, assess and enhance value streams are sought. The StreaM method, which is described in this paper, enables a comprehensive analysis, design and planning of cross-company product and information flows on different levels of value stream detail. At the same time, the entire methodology is based on a common understanding of key symbols, parameters and calculation procedures. In addition, the use of the developed StreaM method and the associated model in a case study proves its practical applicability in an industrial setting. In further validation projects, the transfer of the “Standardized cross-enterprise Value Stream Management Method” to other industry sectors is envisaged to continuously improve energy, trade or service processes. [less ▲]

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See detailNeuro-Inspired Reward-Based Tracking Control for Robotic Manipulators with Unknown Dynamics
Klecker, Sophie UL; Hichri, Bassem UL; Plapper, Peter UL

in Proceedings of the 2017 2nd International Conference on Robotics and Automation Engineering (ICRAE) (2017, December)

Tracking control for robotic manipulators is required for numerous automation tasks in manufacturing engineering. For this purpose, model-free PD-controllers are largely implemented by default in ... [more ▼]

Tracking control for robotic manipulators is required for numerous automation tasks in manufacturing engineering. For this purpose, model-free PD-controllers are largely implemented by default in commercially available robot arms and provide satisfactory performance for simple path following applications. Ever more complex automation tasks however ask for novel intelligent and adaptive tracking control strategies. In surface finishing processes, discontinuous freeform paths as well as changing constraints between the robotic end-effector and its surrounding environment affect the tracking control by undermining the stable system performance. The lacking knowledge of industrial robot dynamic parameters presents an additional challenge for the tracking control algorithms. In this paper the control problem of robotic manipulators with unknown dynamics and varying constraints is addressed. A robust sliding mode controller is combined with an RBF (Radial Basis Function) Neural Network-estimator and an intelligent, biomimetic BELBIC (Brain Emotional Learning-Based Intelligent Control) term to approximate the nonlinear robot dynamics function and achieve a robust and adaptive tracking performance. [less ▲]

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See detailContinuous Improvement of Complex Process Flows by Means of StreaM as the “Standardized Cross-Enterprise Value Stream Management Method”
Oberhausen, Christof UL; Minoufekr, Meysam UL; Plapper, Peter UL

in Proceedings of 2017 IEEE International Conference on Industrial Engineering and Engineering Management (IEEM) (2017, December)

In numerous sectors and industries worldwide, there is a trend towards an intercompany and often international division of value creation and related work tasks. To overcome the challenges of complex ... [more ▼]

In numerous sectors and industries worldwide, there is a trend towards an intercompany and often international division of value creation and related work tasks. To overcome the challenges of complex cross-enterprise supply chain networks, innovative approaches to visualize, assess and enhance value streams are sought. The StreaM method, which is described in this paper, enables a comprehensive analysis, design and planning of cross-company product and information flows on different levels of value stream detail. At the same time, the entire methodology is based on a common understanding of key symbols, parameters and calculation procedures. In addition, the use of the developed StreaM method and the associated model in a case study proves its practical applicability in an industrial setting. In further validation projects, the transfer of the “Standardized cross-enterprise Value Stream Management Method” to other industry sectors is envisaged to continuously improve energy, trade or service processes. [less ▲]

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See detailHuman-Robot-Collaboration for dismantling processes
Groß, Sebastian UL; Gerke, Wolfgang; Plapper, Peter UL

in Müller, Rainer; Plapper, Peter; Brüls, Olivier (Eds.) et al Robotix-Academy Conference for Industrial Robotics (RACIR) 2017 (2017, October)

Remanufacturing of used technical products allows saving of raw material and energy. The complex and mostly manual disassembly of the products prevents the application of remanufacturing in industry. The ... [more ▼]

Remanufacturing of used technical products allows saving of raw material and energy. The complex and mostly manual disassembly of the products prevents the application of remanufacturing in industry. The fully automated dismantling can not be achieved and the manual work causes high labour costs. Companies can profit by remanufacturing. Using human-robot collaboration for disassembly allows a certain degree of automation and provides the flexibility and knowledge of the human. This is a promising approach to economically realise a disassembly and remanufacturing of products which are difficult to disassemble or have a high variance. [less ▲]

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See detailInfluence of laser ablation and plasma surface treatment on the joint strength of laser welded aluminum-polyamide assemblies
Al Sayyad, Adham UL; Bardon, Julien; Hirchenhahn, Pierre et al

Scientific Conference (2017, September 14)

Laser assembly of a metal with a polymer is an innovative process for the development of hybrid lightweight structures. It was already demonstrated that surface treatment of aluminum prior to laser ... [more ▼]

Laser assembly of a metal with a polymer is an innovative process for the development of hybrid lightweight structures. It was already demonstrated that surface treatment of aluminum prior to laser joining has a critical influence on joint strength of laser assembly with polyamide. In this work, further investigation of the influence of surface treatment prior to laser assembly is carried out. In particular, two kind of surface modification pretreatments of aluminum, laser ablation and plasma surface modification, in combination with plasma surface pretreatment of polyamide, were investigated. Surface properties of aluminum and polyamide after pretreatment are compared to their untreated state. More precisely, surface chemistry, surface energy and roughness characteristics are evaluated by X-ray photoelectron spectroscopy (XPS), sessile drop tests and 3D profilometry, respectively. Joint strength of laser assembly of treated aluminum and polyamide is reported. The more influential surface characteristics for the improvement of joint strength are determined, paving the way to significant advances in metal-polymer laser assembly technology. [less ▲]

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See detailChemical Bonds in Laser Welded Aluminum and Polyamide
Hirchenhahn, Pierre; Al Sayyad, Adham UL; Bardon, Julien et al

Presentation (2017, September 14)

Automotive industry is showing an increasing interest towards polymer/metal assemblies, essentially in order to increase fuel efficiency through the reduction of car body weight. In parallel, these ... [more ▼]

Automotive industry is showing an increasing interest towards polymer/metal assemblies, essentially in order to increase fuel efficiency through the reduction of car body weight. In parallel, these assemblies are interesting for biomedical applications, because of the potential to obtain improved or new properties e.g. for implants. Laser welding is considered one of the most promising methods of joining dissimilar materials because of its unique advantages; the process is fast, can be adapted to complex geometries and is totally solvent free, which is a major asset for biomedical applications [1]. A strong adhesion between polyamide 6.6 (PA-6.6) and aluminum (Al) plates was obtained from laser welding in optimized conditions [2]. However, the root causes of this adhesion are not yet understood. Several effects may come into play, such as covalent binding, electrostatic binding, interdiffusion and mechanical interlocking. This is further complicated in “real life” samples by the high roughness of the metal sheet, the additives contained in the polymer, the Al and PA-6.6 surface composition and the difficulty to reach the metal-polymer interface. In order to gain information on the chemical binding between the oxydized Al surface and the PA-6.6, model samples were prepared by spin coating ultrathin PA-6.6 films on polished Al (99.999 % purity) plates (Fig. 1.). The two materials were subsequently welded by laser irradiation. FT-IR, XPS and ToF-SIMS have been used to carry out this study. The interface was reached by sputtering the polymer with low energy Cs+ ions in ToF-SIMS and Ar clusters GCIB in XPS. In this preliminary study, ions binding the Al with polymer were identified in both the positive (AlCH3O+, AlNH+, AlNH2 +, Al2NH+) AlCNO+, AlONH3 +) and negative polarities, (AlN-, AlNO-, AlCO-, AlCNO-). Depth profiles and images near the interface were obtained. Results obtained on our model samples will be compared with laser joints obtained on “real” samples. Ultimately, this work aims at providing guidelines for improving the mechanical resistance of the weld. [less ▲]

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See detailRobotix-Academy Conference for Industrial Robotics (RACIR) 2017
Müller, Rainer; Plapper, Peter UL; Brüls, Olivier et al

Book published by Shaker Verlag - 1st ed (2017)

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See detailResistance measurement of dissimilar Al/Cu laser welds
Schmalen, Pascal Guy UL; Plapper, Peter UL

in Proceedings of LPM2017 - the 18th International Symposium on Laser Precision Microfabrication (2017)

Aluminum and Copper were joined using the laser-based braze-welding process. By avoiding the intermixture of both conductive materials, the formation of brittle intermetallic compounds is strongly reduced ... [more ▼]

Aluminum and Copper were joined using the laser-based braze-welding process. By avoiding the intermixture of both conductive materials, the formation of brittle intermetallic compounds is strongly reduced. This results in a tough, ductile connection with reduced electric resistance. This paper de-scribes a method, which is based on the 4-wire method, to measure the resistance of the weld seam. The arrangement of the conductive electrodes directly on top and bottom of the weld seam signifi-cantly increases the accuracy of the measured resistances, thus offers a direct estimation of the inter-metallic layer thickness. The electric measuring of the layer thickness is a non-destructive method, which assists in the reduction of the post-process effort (cross sections, pull tests, hardness measure-ments) and decreases the lead-time by reducing the time needed for the identification of suitable laser process parameters. [less ▲]

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See detailTowards Intelligent Robot Assistants for the non-destructive Disassembly of End of Life Products
Jungbluth, Jan UL; Plapper, Peter UL; Gerke, Wolfgang

in Plapper, Peter; Hichri, Bassem (Eds.) Robotix-Academy Conference (2017, May 06)

The effective collaboration between humans and robots in complex and task rich environments like End of Life product disassembly depends on the ability of the robot to anticipate the workflow as well as ... [more ▼]

The effective collaboration between humans and robots in complex and task rich environments like End of Life product disassembly depends on the ability of the robot to anticipate the workflow as well as the assistance the human co-worker wants. Our approach towards such an intelligent system is the development of an informed software agent that controls the robot assistance behavior. We inform the agent with procedural and declarative knowledge about the disassembly domain through models of the product structure and actor/object models. The product structure is then transformed to a directed graph and used to build, share and define a goal-orientated coarse workflow. Depending on the tasks and wanted assistance, the system can generate adaptable and detailed workflows through searching in the situation space on the basis of predefined and task dependent actions. The created detailed workflow consists of a sequence of actions that are used to call, parameterize and execute robot programs for the fulfillment of the assistance. The aim of this research is to equip robot systems with higher cognitive skills to allow them to be autonomous in the performance of their assistance to improve the ergonomics of disassembly workstations. [less ▲]

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See detailRobust BELBIC-Extension for Trajectory Tracking Control
Klecker, Sophie UL; Hichri, Bassem UL; Plapper, Peter UL

in Journal of Mechanics Engineering and Automation (2017), 7(2),

In real-life trajectory tracking applications of robotic manipulators uncertain robot dynamics, external disturbances and switching constraints which cannot be accommodated for by a conventional ... [more ▼]

In real-life trajectory tracking applications of robotic manipulators uncertain robot dynamics, external disturbances and switching constraints which cannot be accommodated for by a conventional controller affect the system performance. We suggested an additional control element combining sliding mode and bio-mimetic, neurologically-inspired BELBIC (brain emotional learning-based intelligent control). The former is invariant to internal and external uncertainties and guarantees robust behavior. The latter is based on an interplay of inputs relating to environmental information through error-signals of position and sliding surfaces and of emotional signals regulating the learning rate and adapting the future behaviour based on prior experiences and with the goal to maximize a reward function. We proofed the stability and the performance of the suggested control scheme through Lyapunov theory and numerical simulations, respectively. [less ▲]

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See detailInfluence of Material Moisture during Laser Joining of Polyamide 6.6 to Aluminum
Lamberti, C.; Peral Alonso, Inmaculada UL; Plapper, Peter UL

in Atiner's Conference Paper Series (2017), IND 2017 - 2270

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See detailPID and Biomimetic Variable Structure Path Tracking Control in Automated Surface Finishing Processes
Klecker, Sophie UL; Plapper, Peter UL; Hichri, Bassem UL

in Robotix-Academy Conference for Industrial Robotics (RACIR) 2017 (2017)

This paper addresses freeform surface following control as one of the main challenges in automating surface finishing processes. Successive changes in constraints between the tool attached to the robotic ... [more ▼]

This paper addresses freeform surface following control as one of the main challenges in automating surface finishing processes. Successive changes in constraints between the tool attached to the robotic manipulator and its surroundings are due to complex workpiece-geometries and result in a switched nonlinear system. The control problem of the latter is addressed by industrial state-of-the-art conventional PID control as well as by biomimetic variable structure control which are both applied to a benchmark path tracking problem as characteristically encountered in surface finishing. [less ▲]

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See detailAn intelligent agent-controlled and robot-based disassembly assistant
Jungbluth, Jan UL; Gerke, Wolfgang; Plapper, Peter UL

in Conference Proceedings on the 2nd International Conference on Artificial Intelligence and Robotics ( ICAIR 2017) (2017)

One key for successful and fluent human-robot-collaboration in disassembly processes is equipping the robot system with higher autonomy and intelligence. In this paper, we present an informed software ... [more ▼]

One key for successful and fluent human-robot-collaboration in disassembly processes is equipping the robot system with higher autonomy and intelligence. In this paper, we present an informed software agent that controls the robot behavior to form an intelligent robot assistant for disassembly purposes. While the disassembly process first depends on the product structure, we inform the agent using a generic approach through product models. The product model is then transformed to a directed graph and used to build, share and define a coarse disassembly plan. To refine the workflow, we formulate “the problem of loosening a connection and the distribution of the work” as a search problem. The created detailed plan consists of a sequence of actions that are used to call, parametrize and execute robot programs for the fulfillment of the assistance. The aim of this research is to equip robot systems with knowledge and skills to allow them to be autonomous in the performance of their assistance to finally improve the ergonomics of disassembly workstations. [less ▲]

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See detailResistance Measurement of Laser Welded Dissimilar AlCu Joints
Schmalen, Pascal Guy UL; Plapper, Peter UL

in Journal of Laser Micro/Nanoengineering (2017), 12(3), 189-194

Aluminum and Copper were joined using the laser-based braze-welding process. By avoiding the intermixture of both conductive materials, the formation of brittle intermetallic compounds is strongly reduced ... [more ▼]

Aluminum and Copper were joined using the laser-based braze-welding process. By avoiding the intermixture of both conductive materials, the formation of brittle intermetallic compounds is strongly reduced. This results in a tough, ductile connection with reduced electric resistance. This paper describes a method, which is based on the 4-wire method, to measure the resistance of the weld seam. The arrangement of the conductive electrodes directly on top and bottom of the weld seam significantly increases the accuracy of the measured resistances, thus offers a direct estimation of the inter-metallic layer thickness. The electric measuring of the layer thickness is a non-destructive method, which assists in the reduction of the post-process effort (cross sections, pull tests, hardness measurements) and decreases the lead-time by reducing the time needed for the identification of suitable laser process parameters. [less ▲]

Detailed reference viewed: 112 (4 UL)