07 Fakultät Konstruktions-, Produktions- und Fahrzeugtechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/8
Browse
2 results
Search Results
Item Open Access Process evaluation for smart concrete road construction : road surface and thickness evaluation using high-speed LiDAR technology(2021) Skalecki, Patric; Sesselmann, Maximilian; Rechkemmer, Sabrina; Britz, Thorsten; Großmann, Andreas; Garrecht, Harald; Sawodny, OliverThe enhancement of new quality criteria in highway construction is a key aspect to improving the construction process and lifetime of road. In particular, mobile laser scanning systems are nowadays able to provide realistic 3D elevation profiles of a road to detect anomalies. In this context, this study utilizes a high-accuracy high-speed mobile mapping vehicle and evaluates a weighted longitudinal profile as an improved measure for evenness analysis. For comparison a classical method with a rolling straight edge was evaluated on the same road section and observed effects are discussed. The second focus is the areal reconstruction of the road thickness. For this purpose, a modern method was developed to spatially synchronize two high-speed laser scans using reference boxes next to the road, to transfer the point clouds into a surface model and to calculate the layer thickness. This procedure was conceptually validated by some pointwise measurements of the layer thickness. With this information, imperfections in the base layer could be detected automatically over a wide area at an early stage and countermeasures might be initiated before constructing the highway.Item Open Access Path planning for graded concrete element fabrication(2023) Blagojevic, Boris; Sawodny, OliverThe technology of functionally graded concrete (FGC) is a new methodology in the field of concrete construction, striving for mass savings by adjusting the elements interior design. A promising approach herein is meso-gradation, where concrete hollow spheres are placed inside the formwork before casting the element; this allows up to 50% mass savings without a loss in load-bearing capacity, whilst also ensuring recyclability compared to e.g. bubble decks. In order to prevent damage/displacement of the spheres during automated fabrication, the extruded concrete flow must avoid the spheres, whilst neatly covering the elements area in order to prevent cavities. Both requirements formulate a complex path planning problem that must be solved in order to achieve automated fabrication. In this paper, we propose a method for solving this problem, which is based on theoretical findings on Hamiltonian triangulations. Our approach is based on the idea that the elements area is triangulated, such that all sphere centers are corners of triangles. For each triangle, a smooth path can be planned straightforwardly on a consideration of the geometry, such that the global path is made of a sequence of local ones. This necessitates finding a triangulation that is hamiltonian, i.e. a sequence where all triangles are visited exactly once. To this end, we first present a new class of triangulations and proof their hamiltonicity, followed by an algorithm that generates such triangulations on certain FGC element geometries. This is followed by the local path planning problem, whose special structure with start/end tangential and curvature constraints facilitates the use of a polar coordinate approach.