Now showing 1 - 10 of 104
  • Publication
    PowerGrasp: Development Aspects for Arm Support Systems
    ( 2022)
    Goppold, J.-P.
    ;
    Kuschan, J.
    ;
    Schmidt, H.
    ;
    Krüger, J.
    Exoskeletons can support workers on physically demanding tasks, but in industry they lack of acceptance. This contribution gives an insight into design aspects for upper body exoskeletons, especially how active exoskeletons for industrial applications differ from military and medical use-cases. To overcome typical rigid exoskeleton problems, we suggest the use of modular soft-exosuit support systems and therefore checked different types of soft actuation principles for their eligibility for the use on upper body joints. Most promising approach is using two-layered actuators sting of robust fabric with embedded rubber tubes as pressure chambers. By inflating the tubes, it is possible to vary the stiffness of the chambers, which can be effectively used to generate assisting forces and moments at human joints (shoulder, elbow, wrist, finger).
  • Publication
    Robust system identification for hysteresis-controlled devices using SINDy
    ( 2020)
    Schreck, G.
    ;
    Thiele, G.
    ;
    Fey, A.
    ;
    Krüger, J.
    For advanced control of technical systems reliable system identification methods are essential. The data-driven framework Sparse Identification of Nonlinear Dynamics (SINDy) by Kutz and Brunton is extended in order to tackle hysteresis-controlled systems. In order to gain robustness, a so called proximity hysteron is introduced. This paper presents this extension and documents experiments with simulations of an academic example and an industrial chiller system. A proof of concept is followed by experiments which show that strong nonlinearities as well as inadequate sampling rates can critically impair the algorithm.
  • Publication
    Energy optimal set-points for coupled systems using their topology
    ( 2020)
    Thiele, G.
    ;
    Claus, R.
    ;
    Johanni, T.
    ;
    Krüger, J.
    Energy efficiency is an emerging topic for companies in the industrial sector. The optimization of existing machines by advanced control is increasingly approached. For interconnected systems, we present a general procedure to include topology knowledge in an automated set-point optimization routine. This paper demonstrates an exemplary algorithm, applied to a parallel connection of two chillers for test purposes.
  • Publication
    Point Pair Feature Matching: Evaluating Methods to Detect Simple Shapes
    ( 2019)
    Ziegler, M.
    ;
    Rudorfer, M.
    ;
    Kroischke, X.
    ;
    Krone, S.
    ;
    Krüger, J.
    A recent benchmark for 3D object detection and 6D pose estimation from RGB-D images shows the dominance of methods based on Point Pair Feature Matching (PPFM). Since its invention in 2010 several modifications have been proposed to cope with its weaknesses, which are computational complexity, sensitivity to noise, and difficulties in the detection of geometrically simple objects with planar surfaces and rotational symmetries. In this work we focus on the latter. We present a novel approach to automatically detect rotational symmetries by matching the object model to itself. Furthermore, we adapt methods for pose verification and use more discriminative features which incorporate global information into the Point Pair Feature. We also examine the effects of other, already existing extensions by testing them on our specialized dataset for geometrically primitive objects. Results show that particularly our handling of symmetries and the augmented features are able to boost recognition rates.
  • Publication
    Towards Learning 3d Object Detection and 6d Pose Estimation from Synthetic Data
    ( 2019)
    Rudorfer, M.
    ;
    Neumann, L.
    ;
    Krüger, J.
    Deep Learning-based approaches for 3d object detection and 6d pose estimation typically require large amounts of labeled training data. Labeling image data is expensive and particularly the 6d pose information is difficult to obtain, as it requires a complex setup during image acquisition. Training with synthetic data is therefore very attractive. Large amounts of synthetic, labeled data can be generated, but it is not yet fully understood how certain aspects of data generation affect the detection and pose estimation performance. Our work therefore focuses on creating synthetic training data and investigating the effects on detection performance. We present two methods for data generation: rendering object views and pasting them on random background images, and simulating realistic scenes. The former is computationally simpler and achieved better results, but the detection performance is still very sensitive to small changes, e.g. the type of background images.
  • Publication
    Holo Pick'n'Place
    ( 2018)
    Rudorfer, M.
    ;
    Guhl, J.
    ;
    Hoffmann, P.
    ;
    Krüger, J.
    In this paper we contribute to the research on facilitating industrial robot programming by presenting a concept for intuitive drag and drop like programming of pick and place tasks with Augmented Reality (AR). We propose a service-oriented architecture to achieve easy exchangeability of components and scalability with respect to AR devices and robot workplaces. Our implementation uses a HoloLens and a UR5 robot, which are integrated into a framework of RESTful web services. The user can drag recognized objects and drop them at a desired position to initiate a pick and place task. Although the positioning accuracy is unsatisfactory yet, our implemented prototype achieves most of the desired advantages to proof the concept.
  • Publication
    Maximization of operational workspace of a mobile manipulator system
    ( 2018)
    Kalidindi, V.V.
    ;
    Vick, A.
    ;
    Krüger, J.
    This paper puts forward a proposition of designing manipulator setup on a mobile platform so as to enhance the Operational Workspace range of a given Mobile-Manipulator system, by introducing the concept of Installation angle. This concept is theoretically tested on a Mobile-manipulator system built from the chosen robots, for the given operational parameters. As a part of this testing, Manipulator workspace has been expressed and approximated in terms of its enclosure volume for quantitative comparability.
  • Publication
    Gesture based robot programming using process knowledge
    ( 2018)
    Heimann, O.
    ;
    Hügle, J.
    ;
    Krüger, J.
    This paper is a work in progress report on a novel system for intuitive gesture based robot programming. The major contribution is the addition of an expert system into the robot programming process. The expert system uses static knowledge, such as seam types, and dynamic knowledge to reason about the intended process. The dynamic knowledge holds information about the environment and is derived from sensor data. The paper outlines the required components and the current state of development of a prototype system. An example of the inference process is given for a robot laser welding application.
  • Publication
    An integrated approach for industrial robot control and programming combining haptic and non-haptic gestures
    ( 2017)
    Hügle, J.
    ;
    Lambrecht, J.
    ;
    Krüger, J.
    We present a hybrid programming method for industrial robots combining advantages of manual haptic guidance of the end-effector and programming approaches using non-haptic pointing gestures for the spatial definition of poses and trajectories. Whereas the bare-hand spatial interaction can be implemented and performed cost- and time-efficiently but lacks accuracy, haptic-interaction is more time-consuming but it is used in a reduced manner in order to enable a highly-accurate refinement of target working poses. Additionally, the user is supported by a mobile Augmented Reality simulation providing spatial validation of the robot program, program management and transmission towards the robot controller. The implementation is realized by a compliance control based on a sensor mounted between flange and end-effector combined with our former introduced approach for spatial programming. We conducted a user study comparing Teach-In and Offline programming. The analysis shows a significant reduction of programming duration as well as a reduction of programming errors compared with Teach-In. Most participants favor the hybrid programming system. No significant differences for the programming duration could be determined between experts and non-experts. In comparison between haptic and non-haptic interaction, non-experts favor non-haptic interaction due to the higher intuitiveness of pointing gestures compared to direct physical interaction.
  • Publication
    The working posture controller: Automated assessment and optimisation of the working posture during the process
    ( 2017)
    Nguyen, T.D.
    ;
    Pilz, C.
    ;
    Krüger, J.
    We present the Working Posture Controller (WPC), a novel technology to help workers preventing posture-related Musculo-skeletal disorders. The innovation lies in the fact that the system does not require tedious work place design or process planning, since it automatises these steps. We discuss this technology from different views including a first technical evaluation, discussions concerning use cases, safety and economic and legal challenges when integrating such a technology into the production line.