Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

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Inertial Measurement Unit based Human Action Recognition for Soft-Robotic Exoskeleton

2021 , Kuschan, Jan , Burgdorff, Moritz , Filaretov, Hristo , Krüger, Jörg

Absence from work caused by overloading the musculoskeletal system lowers the life quality of the worker and gains unnecessary costs for both the employer and the health system. Exoskeletons can present a solution. Typically, such systems struggle with stiffness and discomfort and primarily a lack of battery lifetime. Soft-robotic exoskeletons offer a possibility to overcome these problems by increasing the system flexibility, not limiting the supported DoF and being actuator and joint together. Since soft-robotic exoskeletons can be designed only using power when supporting the wearer, it is possible to increase the battery lifetime by only acting on those actions for which the wearer needs support. Dealing with controls for soft-robotic exoskeleton one major difficulty is to find a compromise between saving energy and supporting the wearer. Having an action-depending control can reduce the supported actions to cover only relevant ones and increase the lifetime of the battery. The system conditions are to detect the user actions in real-time and distinguish between actions which require support and those which do not. We contribute an analysis and modification of human action recognition(HAR) benchmark algorithms from activities of the daily living, transferred them onto industrial use cases containing short and mid-term action and reduce the models to be compatible using embedded computers for real-time recognition on soft exoskeletons. We identified the most common challenges for inertial measurement units based HAR and compare the best-performing algorithms using a newly recorded data set overhead car assembly for industrial relevance. As a benchmark data set we focused on the "Opportunity" data set. By introducing orientation estimation, we were able to increase the F1 scores by up to 0.04. With an overall F1 score without a Null-class of up to 0.883, we were able to lay the foundation to use HAR for action dependent force support.

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EnerSEC. Reaktive IT-Sicherheitsüberwachung automatisierter technischer Anlagen in sicherheitskritischen Energie-Infrastrukturen

2018 , Klein, Max , Thiele, Gregor , Horn, Christian , Krüger, Jörg

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A practical approach to reduce energy consumption in a serial production environment by shutting down subsystems of a machine tool

2019 , Can, Alperen , Thiele, Gregor , Krüger, Jörg , Fisch, J. , Klemm, C.

Energy efficiency in production is becoming increasingly important for the automotive industry, motivated by political regulations and competitiveness. Many theoretical approaches to achieve an efficient production via advanced control have only been tested in experimental environments. Important for the transfer into serial production is the proof that all requirements (e.g. quantity and quality) will be met. For ensuring production on demand, machine tools (MT) imitate the real production process to keep themselves at operating temperature. All subsystems of a MT operate at full power in this state, disregarding its necessity. Shutting down these subsystems during non-productive periods is a promising approach for saving energy. This paper will present a method for shutting down components during non-productive periods, while ensuring the ability to produce on demand. Successful tests were already performed during live operation in a plant of a car manufacturer in Berlin, Germany.

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Human robot collaboration - using kinect v2 for ISO/TS 15066 speed and separation monitoring

2018 , Rosenstrauch, Martin J. , Pannen, Tessa J. , Krüger, Jörg

The use of industrial robots within assembly workstations where human and robot should be able to collaborate or even cooperate involve high safety requirements. One out of four possibilities outlined in the current technical specification ISO/TS 15066 for ensuring safety is speed and separation monitoring. Here the robot motion speed in- or decreases dynamically depending on the distance between operator and robot. This paper introduces an approach of a speed and separation monitoring system with the help of a time of flight sensing. After introducing this safety ensuring method, a Microsoft Kinect V2 is used to continuously detect human worker within a shared workspace. With the help of the robots joint angles from the robot control it is possible to compute the distances between all robot joints and the human worker. The shortest distance, which is at the same the critical distance time, is determined and as a consequence the velocity and acceleration values of the robot were set to safe values according to ISO/TS 15066. As it is not necessary to visually detect also the robot, but only human workers, this approach is very resilient. Afterwards the introduced setup is tested by a real detected human in front of a Kinect and a simulated industrial robot (Universal Robot UR5) in the robot operating system ROS. Measurements show that depending on the position of the worker the robots speed adapts to recommended safety values up to a complete halt if necessary. Conclusively all results are discussed and an outlook for possible fields of applications is given.

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Quantification and compensation of systematic errors in pressure measurements applied to oil pipelines

2018 , Thiele, Gregor , Liu, Martin , Chemnitz, Moritz , Krüger, Jörg

The monitoring of pipeline operation is an important research topic, especially for the detection and localization of leaks as well as for an efficient control. For these purposes, physical quantities in pipelines are calculated from measurement data on the basis of a mathematical model. In contrast to static models, adaptive models vary their parameters or even their structure to reach the most probable solution. But in most cases, even the best fit will hold residuals caused by discrepancies between the real system and its model. These residuals allow an estimation of travel-time delays of pressure waves and offsets in pressure values. The basic idea of our approach is to interpret these systematic, time-invariant errors of pressure measurements in pipelines either as sensor displacements or as technical defects. The proposed procedure leads to a hypothesis for a model update, regarding the sensor positions. This displacement compensation as well as a variance analysis was successfully applied to real data from a crude oil pipeline in Europe. A cross validation proves the general capability of the developed method to reduce the uncertainties.

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