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Göteborg, Sweden

Warmefjord K.,Chalmers University of Technology | Carlson J.S.,Fraunhofer Chalmers Center | Soderberg R.,Chalmers University of Technology
CIRP Journal of Manufacturing Science and Technology | Year: 2010

Since the model program in automotive industry gets more and more extensive, the costs related to inspection increase. Therefore, there are needs for more effective inspection preparation. In this paper a method for reducing the number of inspection points using cluster analysis is tested on production data. This leads to reductions evaluated up to 90 percent in the case studies considered. Furthermore, the relation between movements in locators and the resulting movements in inspection points is used to find inspection points particularly suited to monitor the fixtures and its locating points. Those same points are used as input to the cluster analysis and chosen as representatives for the clusters. Using cluster analysis, the sample size is an important matter. The sample size, of course, affects the statistical confidence, but it is also important to choose a sample large enough to contain as many effects as possible related to the different process phenomena that exist over time. Those issues are investigated and a sample size lower than 50 items cannot be recommended. © 2010 CIRP. Source

Eriksson D.,Cornell University | Shellshear E.,Fraunhofer Chalmers Center
Graphical Models | Year: 2016

This paper describes a new efficient algorithm for the rapid computation of exact shortest distances between a point cloud and another object (e.g. triangulated, point-based, etc.) in three dimensions. It extends the work presented in Eriksson and Shellshear (2014) where only approximate distances were computed on a simplification of a massive point cloud. Here, the fast computation of the exact shortest distance is achieved by pruning large subsets of the point cloud known not to be closest to the other object. The approach works for massive point clouds even with a small amount of RAM and is able to provide real time performance. Given a standard PC with only 8GB of RAM, this resulted in real-time shortest distance computations of 15 frames per second for a point cloud having 1 billion points in three dimensions. © 2016 Elsevier Inc. Source

Wallman M.,Fraunhofer Chalmers Center | Sandberg F.,Lund University
Computing in Cardiology | Year: 2016

Atrial fibrillation (AF) is a common and increasingly prevalent condition in the western society. During AF, the AV-node controls ventricular response to the rapid atrial impulses. However, current research indicates that the individual variability in AV-nodal function is large. Thus, characterization of the AV-node is an important step in determining the optimal form of treatment on an individual basis. Here we employ a multilevel modeling approach, comparing a previously presented statistical model with a novel detailed network model of the AV-nodal function during AF. We demonstrate that both models can be fitted to generate output that closely resembles clinical ECG data, and that estimated parameters in the less complex model corresponds to limited ranges of parameters in the more complex model. © 2015 CCAL. Source

Hermansson T.,Fraunhofer Chalmers Center | Bohlin R.,Fraunhofer Chalmers Center | Carlson J.S.,Fraunhofer Chalmers Center | Soderberg R.,Chalmers University of Technology
Journal of Manufacturing Systems | Year: 2013

The automotive industry of today is becoming more focused on electrified and hybrid solutions, where both conventional combustion engines and battery supplied electrical engines need to fit in an already densely packed vehicle. Many quality problems are related do flexible parts. In particular, the assembly of electric cables and wiring harnesses is difficult due to its concealed routing, multiple branching points, weights and the flexibility in the material. To avoid late detection of assembly problems, the assembly aspect must be considered early during conceptual design and production preparation with respect to both feasibility and ergonomics. Development of automatic path planning methods in virtual manufacturing tools supporting deformable parts is therefore highly motivated. This article presents a novel method for automatically planning and finding a smooth and collision-free mounting of connectors in a wiring harness installation. Automatic path planning for deformable objects in general is widely acknowledged as a very difficult problem. To overcome this challenge, we propose a low-dimensional path planning algorithm that operates in the following way: constraint relaxation, handle path planning, unfolding, path smoothing and handle supplementation. The method has been implemented and successfully applied to an industrial test case. © 2013 The Society of Manufacturing Engineers. Source

Hermansson T.,Fraunhofer Chalmers Center | Bohlin R.,Fraunhofer Chalmers Center | Carlson J.S.,Fraunhofer Chalmers Center | Soderberg R.,Chalmers University of Technology
CAD Computer Aided Design | Year: 2016

This article presents a novel and unifying method for routing of flexible one-dimensional components such as cables, hoses and pipes with geometric design constraints. A deterministic and resolution complete grid search is used to find a nominal configuration of the component that is collision-free and satisfies functional and manufacturing constraints. Local refinement is done in tandem with a computationally efficient and physically accurate simulation model based on Cosserat rod theory to ensure that the deformed configuration still satisfies functional constraints when influenced by gravity. Test results show that the method is able to solve industrial scenarios involving complex geometries and real constraints with different objectives in mere seconds. © 2016 Elsevier Ltd. All rights reserved. Source

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