Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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Assembly automation in Europe

1997 , Hsieh, L.-H. , Schmahls, T. , Seliger, G.

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Selection of measuring points and optimization algorithm for automotive door fitting

1996 , Quian, W.-H. , Hsieh, L.-H. , Seliger, G.

The pose uncertainty of the door rleative to the poly-in white robotized assembly can be tackled with a differential adjusting motion of the robot to keep the clearance between them close to the required. We bound that the popular least square method does not denon of such fitting problems refers to the maximum deviation rather than the sum of squared deviations. Aiming at minimizing the former, a new approach to the optimal adjusting during automotive door assembly is presented. Comparative calculations show: the conventional least square mthod may lead to a result with the actual optimal solution, optained by the new method. This paper focuses on the selection of measuring points and the opimization algorithm.

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A flexible laser scanner system for on-line process monitoring

1994 , Seliger, G. , Schuler, H. , Hsieh, L.-H.

This paper describes a geometrical sensor system for on-line process monitoring. The sensor consists of a double ligth stripe laser scanner and a modular software for sensor data processing which have been developed in the scope of an EC ESPRIT III project. The paper presents firstly the industrial requirements revealed by a market survey and the overall system architecture. In the second part of the paper the developed novel software algorithms and an example application of the sensor system are described in detail.

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Programming and navigation of a mobile welding robot

1994 , Seliger, G. , Hsieh, L.-H. , Müller, H.

Tis paper describes the programming and navigation features of the mobile climbing robot MoRoMAG which has been developed for welding of ship sections and large gas vessels. For seam tracking the robot can be equipped with either a laserscanner, an arc sensor or an inductive sensor. Navigation tasks are solved by dead reckoning navigation and laser beam guidance. The user friendly programming of the robot facilitates the teaching-in of large numer of welding parameters required by automated welding. By using mobile climbing robots an increase of productivity can be expected. The application of MoRoMAG in other manufacturing processes is the subject of current research.

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Publication

On the optimization of automobile panel fitting

1996 , Hsieh, L.-H. , Seliger, G. , Qian, W.-H.

The difference between the sum of squared deviations and the maximum deviation was studied. The popular least square method refers to the former, but the criterion of many engineering geometrical problems, including fitting problems, often refers to the latter. As a typical case study, this paper presents a new approach to the optimization of the automobile panel fitting, aiming at minimizing the maximum deviation, based on a systematic analysis of the differential adjusting motion's impact on the variations of gaps/flushes. Comparative calculations show: the conventional least square method may lead to a result with the maximum deviation over thirty percent higher than the actual optimal solution, obtained by new method. Moreover, the latter can cope with different tolerances of different seams explicitly.

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Automated learning system for control and supervision of assembly systems

1995 , Groth, A. , Hsieh, L.-H. , Seliger, G.

Automation has not been applied as widely in assembly as in other manufacturing areas, mainly due to the complexity of operations requiring control of many geometric and technological process parameters. This paper shows that automated learning can be applied to control and supervision of assembly systems for which only a qualitative process model exists. A qualitative process model is built from incomplete a-priori knowledge of processes, facilities and products including essential performance targets. Automated learning algorithms determine optimum process control and supervision strategies based on performance of the assembly system. The process model is updated in real time according to the process results. Critical parameters can be identified and supervision strategies optimized. A prototypical automated bonding system will serve as a practical example showing how automated learning can help determining and verifying control strategies.

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Fuzzy Sensordatenauswertung für das automatisierte Entgraten

1994 , Hsieh, L.-H. , Groth, A. , Yi, H.-C.

Bei der Herstellung von Metallgußteilen entfallen ca. 20-30 % der Gesamtherstellkosten und bis zu 50 % der Fertigungslohnkosten auf die Gußnachbearbeitung. Dies ist auf die geringe Produktivität der weitgehend manuellen Arbeitsvorgänge zurückzuführen. Das Entgraten ist ein Arbeitsvorgang der Gußnachbearbeitung, bei dem der als Grat bezeichnete, in den Fugen der Gußform erstarrte Werkstoff entfernt wird. Ein wesentliches Automatisierungshemmnis ist hier die Kombination großer Maß- und Formtoleranzen der Werkstücke mit großer Varianz des Grates in Position, Form und Maßen. Um den Entgratprozeß zu automatisieren, muß daher die Bearbeitungsbahn stets an das gerade bearbeitete Gußteil angepaßt werden. Bisherige Ansätze für die automatisierte Bahnanpassung basierten meist auf dem Versuch, die Lage des Grates auf dem Werkstück und seinen Querschnitt an verschiedenen Stützpunkten der Bearbeitungsbahn zu ermitteln, um daraus die Bearbeitungspositionen des Werkzeuges zu berechnen.

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An integrated approach for object-oriented assembly system planning and assembly control

1996 , Chang, K.-W. , Hsieh, L.-H. , Schreyer, M.

Characteristics such as decentralized, autonomous, self-planning, self-controlled, and teamwork describe the trends or the nature of modern assembly systems which are usually hybrid. These accompanied with the continuously increasing number of variants and shorter product life cycle require reusable assembly units which are flexible and modular, as well as an efficient job order processing. The system should be free configurable based on the new product structure and features, and the assembly control must integrate the available information used and generated the system planning. This paper presents an integrated approach, starting from product structure to design an object-oriented assembly system model, and based on this computer-internal model to control the assembly sequence and operation according to the job orders. The characteristics of modern assembly will be summarized. The requirements on the planning of such an assembly system and assembly control are postulated. An archite cture for integrated assembly system planning and control will be described. The objects for such a system are then derived. The applicability of this approach will be shown on a concrete example of a subassembly from a transportation vehicles manufacturer.

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Betriebssystem für Laserscanner

1995 , Lorenz, V. , Hsieh, L.-H.

This article describes an operating system for laser scanners based on a flexible approach for measuring data analysis. The system aims at broadening the range of application of laser scanners. It has already proved successful in the case of multilayer arc welding, where the application of the sensor has resulted in a higher security and accuracy of the process.

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Publication

Navigation and control of a mobile climbing robot for shipyards

1994 , Seliger, G. , Hsieh, L.-H. , Müller, H.

This paper describes the navigation and control features of the mobile climbing robot MoRoMAG which has been developed for welding, gas cutting and other manufacturing processes on shipyards. navigation tasks are solved by dead reckoning navigation and laser beam guidance. For weld seam tracking the robot can be equipped with either a laserscanner, an arc sensor or an inductive sensor. The user friendly programming of the robot facilitates an easy teaching-in of a large number of parameters. By using mobile climbing robots an increase of productivity can be expected.

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