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Joint 41st International Symposium on robotics, ISR 2010 and 6th German Conference on robotics 2010, ROBOTIK 2010

作者： Thomas, Ulrike Iser, Rene Institute for Robotics and Mechatronics German Aerospace Center Oberpfaffenhofen Germany Institute for Robotics and Process Control Technical University of Braunschweig Germany

ISBN: (纸本)9781617387197

In this paper, a new probabilistic path planning algorithm is described. The algorithm has been developed for assembly planning purposes, but however it can also be used in similar scenarios. Most assembly planning algorithms apply the so called assembly-by-disassembly strategy, therewith planning starts from the goal position of parts and tries to remove single parts or group of parts. Such problems are characterized by the appearance of many narrow passages. Thus, we have developed an probabilistic algorithm able to find paths even if many of such passages exist. The idea of our path planner emanates from the particle In each iteration, it propagates new samples, discards bad evaluated samples and assigns higher weights to good examples. The evaluation functions propagates the samples to explore free space as well as to condensate on the border of obstacles, which leads samples to pass narrow passages. We have evaluated our path planning algorithm with different examples and compared it to the well-known RRT and PRMplanners. We could achieve good execution times for realistic industrial assembly tasks.

关键词： Iterative methods

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A new Probabilistic Path Planning Algorithm for (Dis)assembly Tasks

A new Probabilistic Path Planning Algorithm for (Dis)assembl...

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Joint international symposium on robotics

作者： Ulrike Thomas Rene Iser Institute for Robotics and Process Control Technical University of Braunschweig

ISBN: (纸本)9783800732739

In this paper, a new probabilistic path planning algorithm is described. The algorithm has been developed for assembly planning purposes, but however it can also be used in similar scenarios. Most assembly planning algorithms apply the so called assembly-by-disassembly strategy, therewith planning starts from the goal position of parts and tries to remove single parts or group of parts. Such problems are characterized by the appearance of many narrow passages. Thus, we have developed an probabilistic algorithm able to find paths even if many of such passages exist. The idea of our path planner emanates from the particle In each iteration, it propagates new samples, discards bad evaluated samples and assigns higher weights to good examples. The evaluation functions propagates the samples to explore free space as well as to condensate on the border of obstacles, which leads samples to pass narrow passages. We have evaluated our path planning algorithm with different examples and compared it to the well-known RRT and PRM planners. We could achieve good execution times for realistic industrial assembly tasks.

关键词： Path planning PASSAGE algorithms Disassembly tasks execution time assembly planning trees (mathematics) narrow passage iterative methods

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A low-cost Hexa platform for efficient force control systems using industrial manipulators

Solid State Phenomena

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Solid State Phenomena 2009年 147-149卷 1-6页

作者： Osypiuk, Rafal Kröger, Torsten Szczecin University of Technology Institute of Control Engineering 26 Kwietnia 10 Szczecin71-126 Poland Technical University of Braunschweig Institute for Robotics and Process Control Muehlenpfordtstrasse 23 BraunschweigD-38106 Germany

This contribution presents a new force control concept for industrial six-degree of freedom (DOF) manipulators, which uses a Hexa platform that provides an active environmental stiffness for all six DOFs. The paper focuses on the Hexa platform and is split into two essential parts: (i) parallel platform construction, and (ii) application of force control with industrial manipulators using a six-DOF environmental stiffness. This mechatronic solution almost gives one hundred percent robustness for stiffness changes in the environment, what guaranties a significant shortening of execution time. © (2009) Trans Tech Publications, Switzerland.

关键词： Force control

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A low-cost Hexa platform for efficient force control systems using industrial manipulators

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作者： Osypiuk, Rafal Kröger, Torsten Szczecin University of Technology Institute of Control Engineering 26 Kwietnia 10 71-126 Szczecin Poland Technical University of Braunschweig Institute for Robotics and Process Control Muehlenpfordtstrasse 23 D-38106 Braunschweig Germany

ISBN: (纸本)3908451655

关键词： Force control

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Human-robot interaction for 3D telemanipulated fracture reduction

Human-robot interaction for 3D telemanipulated fracture redu...

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ACM/IEEE International Conference on Human-Robot Interaction (HRI)

作者： Ralf Westphal Simon Winkelbach Friedrich M. Wahl Thomas Gösling Markus Oszwald Tobias Hüfner Christian Krettek Institute for Robotics and Process Control Technical University of Braunschweig Germany Braunschweig Germany Department of Trauma Surgery Hannover Medical School Germany Hannover Germany

Today, femoral shaft fractures are usually stabilized by means of intramedullary nails. This video presents the development of a telemanipulator system, which, by supporting the fracture reduction process, aims at achieving reliable operation results with high reduction accuracies. First, we present a system using 2D X-ray images as base information for the surgeon to guide the reduction. We show the advantages but also the limitations of this approach, which finally led to the development of a telemanipulator system that is based on 3D imaging data instead.

关键词： Robots Educational institutions Accuracy X-ray imaging Surgery Haptic interfaces Biomedical imaging

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3D visualized robot assisted reduction of femoral shaft fractures: Evaluation in exposed cadaveric bones

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Technology and Health Care 2009年第4期17卷 337-343页

作者： Oszwald, Markus Westphal, Ralf Bredow, Jan Gaulke, Ralph Huefner, Tobias Wahl, Friedrich Krettek, Christian Goesling, Thomas Department of Trauma Surgery Hannover Medical School Hannover 30625 Carl-Neuberg-Str.1 Germany Institute for Robotics and Process Control Technical University of Braunschweig Braunschweig Germany Hospital for Special Surgery Orthopaedic Department New York NY United States

The main problems in intra-medullary nailing of femoral shaft-fractures are leg-length discrepancies and rotational differences with an incidence of 2-18% and 20-40% respectively. These may lead to severe postoperative sequelae such as additional correctional operations and difficult rehabilitation. Insufficient visualization can be considered the main reason for these complications. Finally, retention of the fragments in the correct alignment before nail insertion is difficult. To overcome these problems we established a robotic telemanipulator system to support the reduction process. It was evaluated in 30 fractures of embalmed human femora. Specially programmed software used an image-dataset which was acquired by an isocentric 3D fluoroscope. For visualization, a surface projection was generated. Localization and tracking of the fragments and the robot-arm as well as accuracy measurement was performed by using an optical navigation system. Manipulation was controlled via a force-feedback joystick. This way, collisions of the fragments were transmitted back to the surgeon. At the end of the reduction the robot could rigidly retain the fragments' position. © 2009-IOS Press and the authors. All rights reserved.

关键词： THREE-dimensional imaging in medicine FEMUR -- Wounds & injuries MEDICAL rehabilitation robotics in medicine FRACTURES

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Analysis of manual segmentation in medical image processing

Analysis of manual segmentation in medical image processing

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VIPIMAGE 2007 - 1st ECCOMAS Thematic Conference on Computational Vision and Medical Image processing

作者： Tingelhoff, K. Eichhorn, K.W. Wagner, I. Bootz, F. Kunkel, M.E. Moral, A.I. Westphal, R. Rilk, M. Wahl, F. Department of Otolaryngology Head and Neck Surgery University of Bonn Germany Institute for Robotics and Process Control Technical University of Braunschweig Germany

ISBN: (纸本)9780415457774

Manual segmentation is often used as gold standard for evaluation of automatic segmentation. The purpose of this paper is to describe the problems of manual segmentation and the dubiety of manual segmentation as a gold standard. We realized two experiments in which we determined inter- and intraindividual variability. In the first one ten ENT surgeons and ten medical students segmented the right maxillary sinus and ethmoid sinuses manually on a standard CT dataset of a human head. In the second experiment two participants outlined maxillary sinus and ethmoid sinuses five times consecutively. The manual segmentation was accomplished with custom software. The first experiment shows the variability of manual segmentation which can be caused by components like experience, different interpretations of CT data or different levels of accuracy. The second experiment shows varying results even if one ENT specialist or one manual segmenta-tion expert segments the dataset five times consecutively. © 2008 Taylor & Francis Group,.

关键词： Medical image processing

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Building Local Metrical and Global Topological Maps Using Efficient Scan Matching Approaches

Building Local Metrical and Global Topological Maps Using Ef...

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2008 IEEE/RSJ International Conference on Intelligent Robots and Systems, Pages 526-1042

作者： Rene Iser Friedrich M. Wahl Institute for Robotics and Process Control Technical University of Braunschweig Germany

ISBN: (纸本)9781424420575

This paper describes a new solution of the simultaneous localization and mapping (SLAM) problem. Instead of building one global consistent map, aimed by the most common SLAM techniques, we compute a set of local metrical maps and fuse them to a graph-like structure resulting in a topological map. Thus, our approach does not require a global metrical map consistency. The main contribution of this paper is an algorithm for closing spatial loops. Loop closing means, that a subset of the edges of the graph representing the topological map forms a cycle. To this end we describe a very efficient enhancement of the well-known RANSAC technique for actively recognizing regions explored by the robot previously. This improvement exploits the theory of the birthday attack whose mathematical background is known from cryptography. A fast sample-based scan matcher is employed to compute the local maps. We derive the covariance of the current robot pose from the sample distribution in order to perform a recognition only when loop closing is very likely. Our approach has been implemented and experimental results show its excellent performance.

关键词： Topological maps SLAM Random Sample Matching Scan Matching

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12D force and acceleration sensing: A helpful experience report on sensor characteristics

12D force and acceleration sensing: A helpful experience rep...

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IEEE International Conference on robotics and Automation (ICRA)

作者： Torsten Kroger Daniel Kubus Friedrich M. Wahl Institute for Robotics and Process Control Technical University of Braunschweig Germany

The potential of six-axis acceleration sensors in the field of robotic manipulation applications is quite high and most of it has not been used yet - neither in theoretic literature nor in research experiments. When considering six-joint industrial manipulators with six-axis force/torque and six-axis acceleration sensing, many new possibilities arise: all ten inertial parameters of any object can be identified and objects can be recognized based on these parameters, position control behavior can be improved; non-contact forces can be extracted and force control performance can be improved; visual-servoing methods can use acceleration signals to become more robust. The authors made numerous experiments in the mentioned fields and recognized major weaknesses during the realization of prototypic research setups with six-axis acceleration sensors. These problems regard sensor drift, undesired sensor-internal dependencies as the influence of any distal sensor part, noise, and undesired crosstalk behavior. In order to benefit from acceleration signals, it is important to clearly overcome these problems. This paper analyzes typical systematic errors, characterizes them, and suggests important solution methods for a successful usage of acceleration information.

关键词： Force sensors Acceleration Sensor phenomena and characterization Crosstalk Service robots Robot sensing systems Industrial control Manipulators Position control Force control

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Multi-sensor integration and sensor fusion in industrial manipulation: Hybrid switched control, trajectory generation, and software development

Multi-sensor integration and sensor fusion in industrial man...

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International Conference on Multisensor Fusion and Integration for Intelligent Systems (MFI)

作者： Torsten Kroger Friedrich M. Wahl Institute for Robotics and Process Control Technical University of Braunschweig Germany

The potential of multi-sensor integration in industrial manipulation systems is enormously high - and almost unused in real-world systems and applications. Scientific literature provides plenty of approaches for sensor integration, sensor-guided and sensor-guarded robot control, visual servoing, robot control architectures, and software systems, but it is still one of the major challenges to bring all fields together. Therefore we need a better over-all view onto different domains. This overview paper covers three areas, which play a fundamental role to ldquogluerdquo the above mentioned fields together: 1) The manipulation control system (or architecture) from the control engineerpsilas point of view enabling the usage of hybrid switched systems for robotic manipulation systems. 2) The problem of trajectory generation in hybrid switched control systems. 3) Important aspects on software engineering in the field of robot control architectures. Each of these parts is accompanied by real-world experimental results in order to highlight the relevance and the potential of these technologies.

关键词： Trajectory Robot sensing systems control systems Robots Manipulators Robot control Acceleration

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