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Approach for a General Pose-dependent Model of the Dynamic Behavior of Large Lightweight machine tools for Vibration Reduction

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Procedia CIRP 2016年 41卷 812-817页

作者： Stefanie Apprich Frederik Wulle Armin Lechler Andreas Pott Alexander Verl Institute for Control Engineering of Machine Tools and Manufacturing Units (ISW) Universität Stuttgart Seidenstraße 36 70174 Stuttgart Germany

Large-scale machine tools for the manufacturing of large work pieces, e.g. blades, casings or gears for wind turbines, feature pose-dependent dynamic behavior. Small structural damping coefficients lead to long decay times for structural vibrations that have negative impacts on the production process. Typically, these vibrations are handled by increasing the stiffness of the structure by adding mass. That is counterproductive to the needs of sustainable manufacturing as it leads to higher resource consumption both in material and in energy. Recent research activities have led to higher resource efficiency by radical mass reduction that rely on control-integrated active vibration avoidance and damping methods. These control methods depend on information describing the dynamic behavior of the controlled machine tools in order to tune the avoidance or reduction method parameters according to the current state of the machine. The paper describes the approach for a general pose-dependent model of the dynamic behavior of large lightweight machine tools that provides the necessary input to the aforementioned vibration avoidance and reduction methods to properly tackle machine vibrations. The paper starts with an overview of the state of the art of the pose-dependent dynamic behavior of machine tools followed by the most common methods for vibration avoidance and reduction. Based on the results of an experimental modal analysis of a lightweight machine tool structure, the relevant pose-dependency is shown and the relevant parameters to derive the dynamic behavior are deduced. Then, a general model structure to model the machine tool's dynamic behavior is introduced. After updating the model parameters to different discrete machine poses the dynamical behavior of the model and the real machine tool structure are compared. Finally, it is explained how the model contributes to the actual vibration reduction of lightweight machine tools.

关键词： machine Tool Dynamics Modelling Pose-Dependency

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Automatic Optimal Motion Generation for Robotic Manufacturing Processes: Optimal Collision Avoidance in Robotic Welding

Automatic Optimal Motion Generation for Robotic Manufacturin...

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IEEE International Conference on Automation Science and engineering

作者： Julian R. Diaz P. Thomas Dietz Philip Ockert Alexander Kuss Martin Hagele Alexander Verl Fraunhofer Institute for Manufacturing Engineering and Automation (IPA) Institute for Control Engineering of Machine Tools and Manufacturing Units ISW University of Stuttgart

ISBN: (纸本)9781509024100

Optimal, efficient and intuitive robotic programming is still a challenge in robotic manufacturing and one of the main reasons why robots are not widely implemented in small and medium-sized enterprises (SME). In order to effectively and efficiently respond to the current product variability requirements, SMEs require easy and optimal programmable robotic manufacturing systems in order to achieve profitable and rapid changeover. To make up for this deficiency, this paper proposes a solution approach for computing optimal motions for manufacturing processes based on the interpretation of the manufacturing process and an automatic configuration of a state of the art sample-based algorithm, the Rapidly-exploring Random Tree RRT~* which is provably asymptotically optimal, using as inputs the semantic and mathematical descriptions of the product, process and resource components. The approach is simulated on the example of collision avoidance for different scenarios in robotic welding revealing its functionality and outlining future potentials for the optimal motion generation for robotic manufacturing processes.

关键词： Collision avoidance Manufacturing process PRODUCT HANDLING Robotic welding autoconfiguration Optimal Semantics Robot

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Fast High-Resolution FE-based Simulation of Thermo-Elastic Behaviour of machine Tool Structures

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Procedia CIRP 2016年 46卷 627-630页

作者： Alexander Galant Michael Beitelschmidt Knut Großmann TU Dresden Institute of Machine Tools and Control Engineering 01062 Dresden Germany TU Dresden Institute of Solid Mechanics 01062 Dresden Germany

Thermally induced errors on machine tools are one of the most important error sources in precision machining. Up to 75% of the overall geometrical errors on workpieces are caused by thermal errors of the machine tool [1] . Thermo-elastic FE-analysis of larger machine tool structures results in complex models requiring a lot of computation time. Reducing the computation time is essential for design optimization as well as for control-integrated correction of thermal deformation. This work shows how a complex thermo-elastic FE model of a machine tool assembly can be reduced to a compact time-saving thermo-elastic calculation model. Application of the method introduced in this paper brings a computation time reduction by the order of 1:1000 with practically negligible loss of accuracy. This method will be verified on a frame assembly of a milling machine.

关键词： machine tool thermal error real-time simulation

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Determination of the Wrench-Closure Translational Workspace in Closed-Form for Cable-Driven Parallel Robots

Determination of the Wrench-Closure Translational Workspace ...

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IEEE International Conference on Robotics and Automation

作者： Andreas Pott Werner Kraus Institute for Control Engineering of Machine Tools and Manufacturing Units University of Stuttgart Seidenstr. 36 70174 Germany

ISBN: (纸本)9781467380270

Workspace determination for robots is an important step in analysis and synthesis. A couple of methods for computing the wrench-closure workspace of cable-driven parallel robots were reported in the literature but all methods tend to be time consuming. In this paper, a new algorithm is presented that exploits different techniques to speed up the computation. Pre-computation is largely exploited and benefit are gained both from considerations in computer algebra and efficient numerical routines. Results from the computation of the translational (sometimes also called constant orientation) wrench-closure workspace are presented and performance values are provided. To the best of the authors' knowledge, the method proposed in this paper is superior in terms of computational time to any other approach for workspace computation.

关键词： Determination Wrench-Closure Translational Workspace

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Detection of Workpiece Shape Deviations for Tool Path Adaptation in Robotic Deburring Systems

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Procedia CIRP 2016年 57卷 545-550页

作者： Alexander Kuss Manuel Drust Alexander Verl Fraunhofer Institute for Manufacturing Engineering and Automation IPA Nobelstrasse 12 70569 Stuttgart Germany Institute for Control Engineering of Machine Tools and Manufacturing Units ISW University of Stuttgart Seidenstrasse 36 70174 Stuttgart Germany

Robotic systems have the potential to automate deburring processes along edges of arbitrarily shaped workpieces. The desired robot movement can be realized by proper trajectory planning using the computer-aided design (CAD) model of the manufactured workpiece. A fundamental problem is that geometric shape deviations between the nominal CAD model and the manufactured parts might be beyond acceptable limits for correct execution of the deburring process. This paper proposes a novel, easy to implement and practical approach to detect shape deviations of workpieces for automatic adaptation of robotic deburring processes. The approach only uses dimensional tolerance specifications of the manufactured part provided by the product design to derive possible variations of the workpiece geometry model. A matching process is performed between point clouds for each of the considered variants and a measured point cloud from the manufactured workpiece using an Iterative Closest Point (ICP) approach. Resulting point distances are used for evaluation of shape similarity between the compared point clouds. Finally, the most similar geometry model is identified for subsequent trajectory planning and workpiece localization. Experimental validation is performed by an industrial robot equipped with a stereo camera for shape sensing and a milling tool for subsequent execution of a deburring process. The results demonstrate the effectiveness and practicality of the proposed approach in industrial applications and an increased deburring quality.

关键词： Deburring Industrial Robot System Shape Deviation CAD Model

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CESA~3R: Highly Versatile Plug-and-Produce Assembly System

CESA~3R: Highly Versatile Plug-and-Produce Assembly System

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IEEE International Conference on Automation Science and engineering

作者： Marian Vorderer Stefan Junker Armin Lechler Alexander Verl Corporate Sector Research and Advance Engineering Robert Bosch GmbH Institute for Control Engineering of Machine Tools and Manufacturing Units (ISW) University of Stuttgart

ISBN: (纸本)9781509024100

The presented machinery concept CESA~3R (Concept for engineering free, Scalable, Advanced Automated Assembly system for Rapid ramp up) addresses today's challenges in production such as product variety and quantity variation by enhancing versatility. Central elements are function oriented standardized automation devices, which are technically featured with independent structure recognition and self-descriptive capabilities. A precise localization unit combined with a skill based programming concept allows an automatic configuration and program generation. The devices can be arranged at runtime to automate a given assembly task without additional engineering and programming efforts.

关键词： Assembly systems autoconfiguration Program generation Automation Runtime Programming ramp-up

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Estimating inertial parameters of suspended cable-driven parallel robots — Use case on CoGiRo

Estimating inertial parameters of suspended cable-driven par...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： Philipp Tempel Pierre-Elie Herve Olivier Tempier Marc Gouttefarde Andreas Pott Institute for Control Engineering of Machine Tools and Manufacturing Units (ISW) University of Stuttgart Stuttgart Germany Tecnalia France Batiment 6- Centre Spatial Uni-versitaire Montpellier-Nîmes Montpellier France Laboratoire d'Informatique de Robotique et de Microèlectronique de Montpellier UM - CNRS Montpellier cedex 5 France Universitat Stuttgart Stuttgart Baden-WÃ¼rttemberg DE

Model based open-loop and closed-loop control systems make use of the system's inertial parameters. Unfortunately, not all of these values can be determined analytically nor can they be obtained from simple measurements. Established experiments for inertial parameters estimation have been applied to serial and parallel rigid-link manipulators, yet in very few cases to cable-driven parallel robots. Due to their kinematic properties and their unique setup, cable robots are more sensitive to incorrect estimates of the inertial parameters making it important to obtain such quantities through experiments. In this work, we assess the topic of inertial parameter identification of a parallel flexible-link manipulator exemplified by the suspended cable-driven parallel robot CoGIRo. Identification equations are derived from Newton-Euler equations of motion of an arbitrary point fixed to a rigid-body. Laboratory experiments for identification of the inertial parameters are then introduced and results are presented. Within the limitations of the sensors and data acquisition methods, reasonable results have been obtained, thereby validating the procedure for suspended cable-driven parallel robots.

关键词： Mathematical model Gravity Parallel robots Manipulators Kinematics Mobile communication

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Modeling and analysis of control valves applied in compressor plants with consideration of time-variable factors

Modeling and analysis of control valves applied in compresso...

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MECHATRONIKA International Symposium

作者： Tim Engelberth Anton Dietmair Alexander Verl Institute for Control Engineering of Machine Tools and Manufacturing Units (ISW) University of Stuttgart Stuttgart Germany MAN Diesel & Turbo SE Berlin Germany

ISBN: (纸本)9781509013036

In process industries, compressor plants provide process fluids with certain flows and pressures. The plant behavior may change over the entire life cycle due to component-specific time-variable factors. control valves applied in compressor plants are affected by time-variable factors. Their modeling with consideration of specific time-variable factors is described in this paper. control valves ensure functional reliability of the plant, as they are opened to blow off excessive compressed process fluid in order to prevent surging and thus to protect the compressor from damage. The influences of the time-variable factors fouling, leakage, changing friction force and loss of supply energy are investigated and integrated into the valve model. Fouling of the valve affects the overall flow and control behavior. Further on, leakage can occur in all flooded components and may jeopardize the functional capability, as required pressure values cannot be reached. In order to avoid leakage at the actuator, stuffing boxes are used for sealing the piston rod. These boxes cause friction forces, which depend on tightening force, temperature and wear of the box. Changing of friction force leads to deviating travel paths or even stick-slip effects. Furthermore, the provided pneumatic energy to run the control valve might be variable. Energy sources with insufficient performance lead to significant changes in movement time, because the provided pressure collapses once the control valve is opened. It can be stated that all investigated factors affect the positioning behavior and lead to deviating movement times, travel paths or end positions. The developed modeling approach depicts all of these changes and the gained knowledge can be used for developing diagnosis methods. Several model parts, especially the modeled variable factors, are reusable for other components, like non-return and throttle valves or even the compressor itself. Hence, a diagnosis system for the whole compressor pl

关键词： Valves Actuators Process control Fluids Friction Force Pistons

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Analysis and Design of Computerized Numerical controls for Execution on Multi-core Systems

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Procedia CIRP 2016年 41卷 864-869页

作者： José María Vivanco Matthias Keinert Armin Lechler Alexander Verl Institute for Control Engineering of Machine Tools and Manufacturing Units (ISW) Seidenstr. 36 Stuttgart 70174 Germany Fraunhofer-Gesellschaft Hansastr. 27c Munich 80686 Germany

Multi-core processors offer a performance increment compared to single-core platforms. This leap in performance is desired to be ported to computerized numerical controls. However, in order to profit of the benefits multi-core processors can bring, the software has to be tailored to real parallel execution. In this paper a concept is proposed for partitioning numerical control software functions for being concurrently executed on multi-core systems. Specifically, the interpreter and the cutter radius compensation modules have been analyzed for devising a feasible parallel architecture. The parser algorithm has been implemented following the proposed scheme in a thread-based approach. Experiments were conducted under a real time Linux kernel extension utilizing the PREEMPT_RT patch. The results were compared against its serial version in terms of execution times to validate the concept.

关键词： Computerized numerical control Multi-core Parallel computing

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Transferring knowledge from research to industry: Experiences from Germany 19

Transferring knowledge from research to industry: Experience...

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19th Pacific Asia Conference on Information Systems, PACIS 2015

作者： Helbig, Michaela Wiemer, Hajo Weller, Jens Institute of Machine Tools and Control Engineering Dresden University of Technology Dresden Germany

In the past 10 years a research cluster in engineering science has been set up to create completely new materials as well as appropriate machines and production processes. To support the collection, storage and analysis of complex process data within that cluster several IT & process management methods and tools have been developed. Now entering the final stage of the cluster, the focus changes to the efficient usage of the created knowledge. To support the technology transfer process the previously created methods and tools are enhanced. In this paper, a software system supporting the controlled and secure transfer of engineering knowledge from research to industry is presented.

关键词： Technology transfer

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