Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Assembly automation in Europe
    ( 1997)
    Hsieh, L.-H.
    ;
    Schmahls, T.
    ;
    Seliger, G.
  • Publication
    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.
  • Publication
    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.
  • 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.
  • Publication
    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.
  • Publication
    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.
  • Publication
    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.
  • Publication
    Erkennung formvarianter Geometrien mit einem Laserscanner auf der Basis evolutionärer Algorithmen
    ( 1994)
    Seliger, G.
    ;
    Hsieh, L.-H.
    ;
    Voit, L.
    ;
    Schuler, H.
    In this paper, we describe a new geometry measurement system with a robot guided laser scanner which is capable to handle new applications by its recognition and configuration flexiblity. By the use of an optimization algorithm basing on revolutionary algorithms it is able to determine both, geometry and position deused for guidance of automated assembly processes. By the example of sensor guided welding of car door hinges it will be shown how the new geometry recognition system tackies automated robot guided assembly.
  • Publication
    Computer-aided planning system for multiple laser-scanner applications
    ( 1994)
    Schuler, H.
    ;
    Hsieh, L.-H.
    ;
    Seliger, G.
    Laser scanners are efficient tools for on-line inspection of workpiece dimensions and for closed-loop process control.Relevant industrial applications require frequently multiple scanners to acquire many significant dimensions of the workpiece at the same time.One of the most crucial tasks hereby is to determine the spatial arrangement of multiple scanners.Until now, this task has been achieved by triel and error.Heuristic rules are available for simple geometry but not available for complicated workpiece geometry.The effectiveness of this planning approach can only be checked after the physical system installation.This paper presents a computer-aided planning system which derives an optimal spatial arrangement of the multi-scanner setup for 2-dimensional measurement tasks automatically.The necessary inputs of the system are the geometry of the workpiece, the regions of interest on the workpiece and the technical specifications of the sensors.Effects of changing properties such as accu racy or range of the selected sensors can be studied through a realistic sensor simulation. (RSS).The accuracy of the multi scanner setup can be verified on the planning system by specifying the accuracy and the relative arrangement of the single scanners.
  • 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.