Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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  • Publication
    Industrial Robot Programming Methods: A Scoping Review
    ( 2020)
    Heimann, Oliver
    ;
    Guhl, Jan
    Easy-to-use programming methods for robotic manufacturing systems are a key element in enabling a wider audience to benefit from increasing automation. This paper provides an overview of current programming methods for industrial mating operations. More specifically, the review focuses on programming methods for welding and assembly tasks. While welding is mainly concerned with the exact definition of the free space trajectories, assembly tasks revolve around the contact with the environment. Thus, the two tasks at hand not only represent two of the most common robotic applications, but also two distinct groups of operations that place very different demands on the programming interface.
  • Publication
    Variable-Latency Networked P-PI and MPC Controller Performance for Industrial Robots
    ( 2019)
    Vick, Axel
    ;
    Kilinc, Ali
    ;
    Guhl, Jan
    The controller design for industrial robot joint positioning is based on fixed cycle times and accurate modeling. Applying closed loop systems to decentralized control networks with variable connection properties would lead to unacceptable performance drops of the controlled mechanism. On the other hand service-oriented and networked control modules are providing full flexibility of location independent execution. But using wide-area connection like internet or wireless networks is yielding unpredictable latency and jitter conditions. That is not well handled by standard feedback controllers like PID or P-PI cascades. This paper presents the comparison of a modified MPC to a standard P-PI controller. That comparison reveals the strengths and weaknesses of each approach regarding controller performance under different communication conditions. Reusing the MPC control trajectory allows the robot to follow a small open-loop trajectory during latency deviation. That improves the performance criteria like overshoot and damping significantly. The overall robustness of the modified MPC is demonstrated empirically by extensive experiments with an laboratory industrial robot.
  • Publication
    Combining the Advantages of On- and Offline Industrial Robot Programming
    ( 2019)
    Guhl, Jan
    ;
    Nikoleizig, Sylvio
    ;
    Heimann, Oliver
    ;
    Hügle, Johannes
    ;
    Krüger, Jörg
    Classic off- and online programming approaches offer different advantages but cannot provide intuitive programming as it would be needed for frequent reconfiguration of industrial robotic cells and their programs. While a simulation and therewith a collision control can be used offline, highest precision can be achieved by using online teach-in. We propose a system that combines the advantages of both offline and online programming. By creating a programming framework that is independent of in- and output devices we allow the use of augmented as well as virtual reality. Thus, enabling the user to choose for a programming technique that best suits his needs during different stages of programming. Bringing together both methods allows us to not only drastically reduce programming time but simultaneously increase intuitiveness of human robot interaction.
  • Publication
    Enabling Human-Robot-Interaction via Virtual and Augmented Reality in Distributed Control Systems
    ( 2018)
    Guhl, Jan
    ;
    Hügle, Johannes
    ;
    Krüger, Jörg
    Production and assembly lines are nowadays transforming into flexible and interconnected cells due to rapidly changing production demands. Changes are, for example, varying locations and poses for the processed work pieces and tools as well as the involved machinery like industrial robots. Even a variation in the combination or sequence of different production steps is possible. In case of older involved machines the task of reconfiguration and calibration can be time consuming. This may lead, in addition with the expected upcoming shortage of highly skilled workers, to future challenges, especially for small and medium sized enterprises. One possibility to address these challenges is to use distributed or cloud-based control for the participating machines. These approaches allow the use of more sophisticated and therefore in most cases computationally heavier algorithms than offered by classic monolithic controls. Those algorithms range from simple visual servoing applications to more complex scenarios, like sampling-based path planning in a previously 3D-reconstructed robot cell. Moving the computation of the machine's reactions physically and logically away from the machine control complicates the supervision and verification of the computed robot paths and trajectories. This poses a potential threat to the machine's operator since he/she is hardly capable of predicting or controlling the robot's movements. To overcome this drawback, this paper presents a system which allows the user to interact with industrial robot and other cyber physical systems via augmented and virtual reality. Captured topics in this paper are the architecture and concept for the distributed system, first implementation details and promising results obtained by using a Microsoft HoloLens and other visualization devices.
  • Publication
    Visualizing trajectories for industrial robots from sampling-based path planning on mobile devices
    ( 2018)
    Guhl, Jan
    ;
    Vick, Axel
    ;
    Vonasek, Vojtech
    ;
    Krüger, Jörg
    Production lines are nowadays transforming into flexible modular and interconnected cells to react to rapidly changing product demands. The arrangement of the workspace inside the modular cells will vary according to the actual product being developed. Tasks like motion planning will not be possible to precompute. Instead, it has to be solved on demand. Planning the trajectories for the industrial robots with respect to changing obstacles and other varying environment parameters is hard to solve with classical path planning approaches. A possible solution is to employ sampling-based planning techniques. In this paper we present a distributed sampling-based path planner and an augmented reality visualization approach for verification of trajectories. Combining the technologies ensures a confirmed continuation of the production process under new conditions. Using parallel and distributed path planning speeds up the planning phase significantly and comparing different mobile devices for augmented reality representation of planned trajectories reveals a clear advantage for hands-free HoloLens. The results are demonstrated in several experiments in laboratory scale.