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Path planning of energy-efficient automated guided vehicles material transportation in manufacturing
(2026)
Automated guided vehicles systems (AGVS) are of increasing importance regarding material transportation in manufacturing since companies can benefit from the application of these systems. However, AGVS cause high energy consumption for material transportation. This consumption can vary within material transportation paths due to movements such as turns, which may lead to deceleration and acceleration of the vehicle. Hence, planning energy-efficient paths for AGVS-conducted material transportation processes is of great importance, but it leads to a high planning effort within the companies. This paper describes the development of a novel method that facilitates manufacturing companies to plan energy-efficient paths for AGVS-conducted material transportation processes with low effort. First, relevant requirements for the method are defined. Then, an existing pathfinding algorithm is selected based on the predefined requirements. Afterwards, a general framework for determining optimal paths of AGVS in manufacturing facilities regarding energy consumption is developed prior to the description of a holistic procedure for planning energy-efficient paths in manufacturing. Finally, the method is validated for a sample manufacturing environment.
A POF integral length and extension sensor based on phase detection of intensity modulated light with fiber sensor lengths beyond 100 m for monitoring large infrastructures is discussed. A theory for a scaling law of the precision limit over length and modulation frequency is presented. Experimental results using green light for sensor ranges above 100 m are shown.
To extend the lifespan of polymer electrolyte membrane fuel cells and electrolyzers, it is crucial to understand local degeneration processes in membrane electrode assemblies (MEAs). We developed a spatially resolved analytical method that can differentiate between various functional and structural degeneration phenomena during the aging process of a membrane by combining scanning electrochemical microscopy (SECM) with a diffusion flow cell and using hexacyanidoferrate(II) and protons as redox mediators. One SECM scan at a negative potential detects proton diffusion through the membrane, thereby measuring its proton conductivity. A second SECM scan at a positive potential visualizes iron complex diffusion through the membrane, highlighting perforating structural damage, such as cracks and holes. This method has been successfully validated for spatially resolving membrane damage following various aging tests.
Serielle Modernisierung
(2024)
Was kann der moderne Holzbau in der Gebäudemodernisierung leisten? Mit dieser Frage haben sich die Holzbau Lehrstühle der TU München in Zusammenarbeit mit internationalen Forschungs- und Praxispartner von 2007 bis 2013 in mehreren Forschungsprojekten beschäftigt. In der Folge sind einige Bauprojekte realisiert worden. Die umfassende Gebäudemodernisierung hatte aber nicht wirklich Fahrt aufgenommen.
Mit der Bundesförderung für effiziente Gebäude BEG soll sich das nun ändern. Für den Holzbau öffnet sich nun ein Fenster der Möglichkeiten für die Modernisierung bestehender Gebäude. Die große Chance für den modernen Holzbau liegt in langjährigen Erfahrungen mit vorgefertigten Bauteilen als Tafel- oder Raumzellenbauweise. Für Ausführungsqualität und
Wirtschaftlichkeit in der Bestandsanierung entsteht durch große Tafelbauelemente, die in unterschiedlicher Weise auf die Gebäudegeometrie angepasst werden. Dies ist ein signifikanter Vorteil gegenüber baustellenproduzierten Verfahren.
Ein oberflächennahestes Geothermiesystem wird aufgrund der ungedämmten Rohrleitungen und der Verlegung in 1 m bis 2 m Tiefe durch verschiedenste klimatische und hydrogeologische Rahmenbedingungen beeinflusst. Durch eine hygrothermische Simulationsanalyse konnten diese Einflussgrößen kategorisiert und bewertet werden. Dabei ist neben den klimatischen Rahmenbedingungen die Datengrundlage, wie die Einschätzung des Wasserhaltevermögens des Erdreichs und deren Wärmeleitfähigkeit sowie die Bodendichte, elementar. Dies führt zu teilweise signifikanten Änderungen des spezifischen Energieentzugs eines oberflächennahesten Geothermiesystems.Es wurde eine Parameterstudie zur Einschätzung der Einflussgrößen durchgeführt und die wichtigsten Einflussfaktoren ermittelt und bewertet. Die Ergebnisse der Einflussgrößen auf oberflächennaheste Geothermiesysteme führen zur verbesserten Einschätzung des Energieentzugs unter bestimmten klimatischen und bodenbedingten Randbedingungen.Die Simulationsergebnisse zeigen teils deutliche Unterschiede zu den bisher in der Fachwelt bekannten Werten der VDI 4640-2 und könnten als Basis für weitere Untersuchungen dienen.
The paper presents a theoretical analysis of different feedback concepts for active vibration control of rotating machines with current-controlled electrodynamic actuators between the machine feet and the steel frame foundation. A generalized mathematical formulation—based on a detailed formulation and on simplified formulations—has been derived, which can be used for different vibration models with different degrees of discretization. In the simplified mathematical formulations, the control parameters are implemented directly in the stiffness and damping matrix of the vibration system or, under special conditions, even directly in the stiffness and damping coefficients of the actuators. For these limit conditions, the controlled system can be replaced by a substituted mechanical system, which allows rapid predictions and optimizations regarding active vibration control of rotating machines without too much effort. Based on the generalized mathematical formulations, a very simplified model of an induction motor is analyzed with typical excitations such as mechanical unbalance, electromagnetic forces in the air gap, and vibrations of the base. The paper shows how the vibration system is affected by different feedback concepts and demonstrates the effectiveness of these concepts.
Purpose: In this work, active vibration control of rotating machines mounted on active machine foot mounts is investigated.
Methods: Therefore, a simplified 3D model is derived and the mathematical coherences are described. Different mathematical solutions are presented for special boundary conditions and a method called “vibration mode coupling by asymmetry” is derived.
Results: It could be shown that a symmetrical system with a machine design, where the center of gravity lies symmetrically between the machine feet with a vertical distance, and where all actuators are identical, represents a system, where all vibration shapes but one can be influenced by the controllers, when the gyroscopic effect can be neglected. In this case, a special vibration shape occurs—where the machine is only rotating at its vertical axis—which cannot be influenced by the controllers. When the stiffness and/or damping in axial and/or horizontal direction of only one actuator will be changed—which will lead to an asymmetrical system—the vibration shape with pure rotation at the vertical axis will not exist anymore. Now, the vibration shapes will become more coupled and they all can be influenced by the controllers, which is here called “vibration mode coupling by asymmetry”.
Conclusions: With the here presented method of “vibration mode coupling by asymmetry”, all vibrations mode shapes can
now be active controlled.
In the paper a theoretical analysis is deduced regarding vibration control of large induction motors – power rating >=1 MW – with roller bearings, using actuators between motor feet and a soft steel frame foundation. Based on a multibody model, the mathematical coherences are shown, including the feedback control system. Afterwards a numerical example of a soft mounted, converter driven, 2-pole induction motor (1.6 MW) with ball bearings is presented, where the bearing housing vibrations and the foundation vibrations are analyzed with and without control system. It could be shown, that without vibration control system the operating speed range cannot be used completely because of resonances, caused by the soft foundation. Therefore, critical speed areas occur, where steady state operation is not possible. However, with the vibration control system, the whole operating speed range can be used. The aim of the paper is to show the capability of using a vibration control system with actuators between motor feet and a soft foundation, for avoiding off-limits areas for the operation speed of large induction motors.