Fraunhofer-Institut für Optronik, Systemtechnik und Bildauswertung IOSB

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  • Publication
    Optimisation of manufacturing process parameters using deep neural networks as surrogate models
    ( 2018)
    Pfrommer, J.
    ;
    Zimmerling, C.
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    Liu, J.
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    Kärger, L.
    ;
    Henning, F.
    ;
    Beyerer, J.
    Optimisation of manufacturing process parameters requires resource-intensive search in a high-dimensional parameter space. In some cases, physics-based simulations can replace actual experiments. But they are computationally expensive to evaluate. Surrogate-based optimisation uses a simplified model to guide the search for optimised parameter combinations, where the surrogate model is iteratively improved with new observations. This work applies surrogate-based optimisation to a composite textile draping process. Numerical experiments are conducted with a Finite Element (FE) simulation model. The surrogate model, a deep artificial neural network, is trained to predict the shear angle of more than 24,000 textile elements. Predicting detailed process results instead of a single performance scalar improves the model quality, as more relevant data from every experiment can be used for training. For the textile draping case, the approach is shown to reduce the number of resource-intensive FE simulations required to find optimised parameter configurations. It also improves on the best-known overall solution.
  • Publication
    Acquisition and evaluation of illumination series for unsupervised defect detection
    ( 2011)
    Gruna, R.
    ;
    Beyerer, J.
    Analyzing scenes under variable illumination has been an important and widely studied research area in the field of machine vision. In this article, we present an illumination device for capturing image series of small objects under variable illumination directions. Due to using a digital projector as programmable light source and a parabolic reflector to reflect the emitted illumination patterns, the device dispenses with the need of moving parts. Furthermore, we demonstrate the utility of illumination series for unsupervised surface defect detection by applying statistical anomaly detection to the measured reflectance data. To this end, we show how relevant illumination directions can be determined without using labeled information by a clustering-based approach.
  • Publication
    3D fusion of stereo and spectral series acquired with camera arrays
    ( 2011)
    Gheta, I.
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    Heizmann, M.
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    Beyerer, J.
  • Publication
    Materialidentifikation mittels optisch realisierter Kreuzkorrelation der Reflektanzspektren
    ( 2011)
    Sauerland, M.
    ;
    Gruna, R.
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    Beyerer, J.
    Dieser Artikel stellt ein neuartiges, zum Patent angemeldetes Messverfahren [1] vor, welches die Ähnlichkeit zweier Spektren in Form eines normierten Kreuzkorrelationskoeffizienten (nKK) bemisst. Die Besonderheit liegt in der optische Realisierung des Verfahrens. Auf Grundlage des nKK wird eine Messgleichung entwickelt, die dann zur Herleitung des Signal-zu-Rausch Verhältnisses genutzt wird. Als Experiment wird die Aufgabenstellung behandelt, metamere Farben anhand ihrer Spektren zu unterscheiden. Gewonnene Messergebnisse werden abschließend mit einem vorhergesagten Ergebnis verglichen.
  • Publication
    Segmentation of printed gray scale dot matrix characters
    ( 2010)
    Grafmüller, M.
    ;
    Beyerer, J.
    There are many kinds of printed dot matrix fonts. They mainly differ in characters' structure since some of them are built with touching dots and some not. Two more variations an efficient character segmentation method has to cope with are fonts printed in italic and illumination changes depending on the environmental conditions. Hence, a procedure is introduced that uses the projection profile of the mean of several least gray values to estimate the skew angle of text lines and the characters' slant angle. Furthermore, based on the projection profile the decision boundaries for line and character segmentation are estimated with a least squares estimator. This has the advantage that the boundaries are adapted for every image. Finally, skew and slant angles are corrected and the characters are segmented. The robustness and accuracy is shown in experiments on data captured with an industrial camera.
  • Publication
    Planning cooperative motions of cognitive automobiles using tree search algorithms
    ( 2010)
    Frese, C.
    ;
    Beyerer, J.
    A tree search algorithm is proposed for planning cooperative motions of multiple vehicles. The method relies on planning techniques from artificial intelligence such as A* search and cost-to-go estimation. It avoids the restrictions of decoupling assumptions and exploits the full potential of cooperative actions. Precomputation of lower bounds is used to restrict the search to a small portion of the tree of possible cooperative actions. The proposed algorithm is applied to the problem of planning cooperative maneuvers for multiple cognitive vehicles with the aim of preventing accidents in dangerous traffic situations. Simulation results show the feasibility of the approach and the performance gain obtained by precomputing lower bounds.
  • Publication
    Instanzorientierte Zugriffskontrolle für den Einsatz in Sensornetzwerken
    ( 2010)
    Vagts, H.
    ;
    Beyerer, J.
    In Service Orientierten Architekturen (SOA) wird Softwarefunktionalität in Diensten gekapselt und ist über standardisierte Schnittstellen ansprechbar. In sensordatenverarbeitenden SOAs können Dienste in zwei Klassen aufgeteilt werden, high-level Dienste und low-level Dienste. Letztere bieten Schnittstellen für (intelligente) Sensoren, erstere kapseln Algorithmen und Auswertungsfunktionen auf hohem Abstraktionsniveau. Die Mehrfachverwendung (Instanziierung) von high-level Dienste in verschiedenen Prozessen führt zu Sicherheitsproblemen. Klassische Zugriffskontrollmodelle (z. B. RBAC) greifen für ein dynamisches Umfeld zu kurz oder sind (z. B. TBAC) nicht praxistauglich. Diese Arbeit stellt einen neuen Ansatz instanzorientierte Zugriffskontrolle vor.
  • Publication
    Ein objektangepasstes Beleuchtungsverfahren für die automatische Sichtprüfung
    ( 2010)
    Gruna, R.
    ;
    Beyerer, J.
    In fast allen Anwendungsbereichen der automatischen Sichtprüfung hat die Wahl der Beleuchtung für die Bildaufnahme einen entscheidenden Einfluss auf die Zuverlässigkeit der nachfolgenden Bildverarbeitung und -auswertung. Viele Inspektionsaufgaben haben zum Ziel, Abweichungen von einem zuvor definierten Sollzustand zu erkennen und zu detektieren. In diesem Artikel wird ein objektangepasstes Beleuchtungsverfahren vorgestellt, das eine optische Änderungsdetektion realisiert und somit Abweichungen von einem definierten Sollzustand direkt im Inspektionsbild ohne weiter Bildverarbeitungsoperationen sichtbar macht. Ein Vergleich des Verfahrens mit herkömmlicher Differenzbildbildung zur Änderungsdetektion zeigt, dass unter plausiblen Annahmen das vorgestellte objektangepasste Beleuchtungsverfahren zu einem besseren Signal-Rauschabstand führt.
  • Publication
    Global evaluation of focussed Bayesian fusion
    ( 2010)
    Sander, J.
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    Heizmann, M.
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    Goussev, I.
    ;
    Beyerer, J.
    Information fusion is essential for the retrieval of desired information in a sufficiently precise, complete, and robust manner. The Bayesian approach provides a powerful and mathematically funded framework for information fusion. By local Bayesian fusion approaches, the computational complexity of Bayesian fusion gets drastically reduced. This is done by a concentration of the actual fusion task on its probably most task relevant aspects. In this contribution, further research results on a special local Bayesian fusion technique called focussed Bayesian fusion are reported. At focussed Bayesian fusion, the actual Bayesian fusion task gets completely restricted to the probably most relevant parts of the range of values of the Properties of Interest. The practical usefulness of focussed Bayesian fusion is shown by the use of an example from the field of reconnaissance. Within this example, final decisions are based on local significance considerations and consistency arguments. As shown in previous publications, the absolute values of focussed probability statements represent upper bounds for their global values. Now, lower bounds which are obtained from the knowledge about the construction of the focussed Bayesian model are proven additionally. The usefulness of the resulting probability interval scheme is discussed.
  • Publication
    Skill-based telemanipulation by means of intelligent robots
    ( 2010)
    Notheis, S.
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    Milighetti, G.
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    Hein, B.
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    Wörn, H.
    ;
    Beyerer, J.
    In order to enable robots to execute highly dynamic tasks in dangerous or remote environments, a semiautomatic teleoperation concept has been developed and will be presented in this paper. It relies on a modular software architecture, which allows intuitive control over the robot and compensates latency-based risks by using Augmented Reality techniques together with path prediction and collision avoidance to provide the remote user with visual feedback about the tasks and skills that will be executed. Based on this architecture different skills with high dynamics are integrated in the robot control, so that they can be executed autonomously without the delayed feedback of the user. The skill-based grasping by adherence of smooth or fragile objects during a remote controlled picking and placing task will be exemplary presented.