| 1. |
- Björkenstam, Staffan C, 1981, et al.
(author)
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Assembly path planning by distance field based shrinking
- 2012
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In: Proceedings of the 4th CIRP Conference on Assembly Technologies and Systems: Technologies and Systems for Assembly Quality, Productivity and Customization, Editor: Professor S. Jack Hu, May 20- 22, 2012, Ann Arbor, Michigan, USA. - 9780615640228 ; 4, s. 179-182
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Conference paper (peer-reviewed)abstract
- This paper presents a method to support dynamic packing in cases when no collision-free path can be found. The method, which is primarily based on path planning and shrinking of geometries, suggests a minimal geometry design change that results in a collision-free assembly path. A new method to shrink geometry based on adaptively sampled distance fields is suggested. Compared to previous work, the new method is less sensitive to input mesh quality. The method works directly on the triangle mesh and requires neither tetrahedralization nor calculation of a medial axis. The algorithm paired with a state of the art path planner has been applied to several industrial cases demonstrating that the proposed method can be used effectively for assembly verification during geometry design.
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| 2. |
- Bohlin, R., et al.
(author)
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Automatic creation of virtual manikin motions maximizing comfort in manual assembly processes
- 2012
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In: Technologies and Systems for Assembly Quality, Productivity and Customization. - : Conference on Assembly Technologies & Systems (CIRP). - 9780615640228 ; , s. 209-212
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Conference paper (peer-reviewed)abstract
- Effective simulation of manual assembly operations considering ergonomic load and clearance demands requires detailed modeling of human body kinematics and motions, as well as a tight coupling to powerful algorithms for collision-free path planning. The focus in this paper is a unified solution that automatically creates assembly motions for manikins taking kinematic constraints, balance, contact forces, collision avoidance and comfort into account. The manikin used in this work has 162 degrees of freedom - six exterior fictitious joints determine the position of the lower lumbar and the remaining ones are interior joints. The inverse kinematic problem leads to an underdetermined system allowing us to pick a solution that maximizes a scalar valued comfort function. The comfort function offers a generic way to give preference to certain poses while avoiding others, typically by considering joint limits, forces and moments on joints, and magnitude of contact forces. In order to avoid collisions, poses close to collision are penalized. The method is implemented and demonstrated on two challenging assembly operations taken from the automotive industry.
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| 3. |
- Lindau, Björn, 1961, et al.
(author)
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Statistical shape modeling in virtual assembly using PCA-technique
- 2012
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In: Technologies and Systems for Assembly Quality, Productive and Customization; ed. by Jack S. Hu; Proceedings of the 4th CIRP Conference on Assembly Technologies and Systems May 21 - 22, 2012, Ann Arbor, Michigan, USA. - 9780615640228 ; , s. 119 - 124
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Conference paper (peer-reviewed)abstract
- The use of virtual assembly tools is one way to understand and improve the geometric product tolerance setting and the conditions for successful manufacturing. Recent developments enable consideration to be given to the deformability of parts when joined. However, in order to produce reliable results, the geometric faults of the mating surfaces must be correctly assumed. In this paper, statistical shape models built on the Principal Component Analysis-technique are proposed to be used to describe the part variation. A generalized model is presented. Furthermore, the underlying intentions and implications are discussed. The method is exemplified using the tool RD&T. In the presented case, a non-rigid sheet metal assembly is modeled and distorted to create a set of sample shapes from which a statistical model is built. In the result, the statistic representation bears a good resemblance to the nominal distorted model when the two are compared.
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