600 Technik, Technologie
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A new underwater 3D scanning device based on structured illumination and designed for continuous capture of object data in motion for deep sea inspection applications is introduced. The sensor permanently captures 3D data of the inspected surface and generates a 3D surface model in real time. Sensor velocities up to 0.7 m/s are directly compensated while capturing camera images for the 3D reconstruction pipeline. The accuracy results of static measurements of special specimens in a water basin with clear water show the high accuracy potential of the scanner in the sub-millimeter range. Measurement examples with a moving sensor show the significance of the proposed motion compensation and the ability to generate a 3D model by merging individual scans. Future application tests in offshore environments will show the practical potential of the sensor for the desired inspection tasks.
Visual perception of surfaces is of utmost importance in everyday life. Therefore, it comes naturally, that different surface structures evoke different visual impressions in the viewer even if the material underlying these surface structures is the same. This topic is especially virulent for manufacturing processes in which more than one stakeholder is involved, but where the final product needs to meet certain criteria. A common practice to address such slight but perceivable differences in the visual appearance of structured surfaces is that trained evaluators assess the samples and assign a pass or fail. However, this process is both time consuming and cost intensive. Thus, we conducted two studies to analyze the relationship between physical surface structure parameters and participants visual assessment of the samples. With the first experiment, we aimed at uncovering a relationship between physical roughness parameters and visual lightness perception while the second experiment was designed to test participants' discrimination sensitivity across the range of stimuli. Perceived lightness and the measured surface roughness were nonlinearly related to the surface structure. Additionally, we found a linear relationship between the engraving parameter and physical brightness. Surface structure was an ideal predictor for perceived lightness and participants discriminated equally well across the entire range of surface structures.
Melt electrowriting, a high‐resolution additive manufacturing technology, has so far been developed with vertical stacking of fiber layers, with a printing trajectory that is constant for each layer. In this work, microscale layer shifting is introduced through deliberately offsetting the printing trajectory for each printed layer. Inaccuracies during the printing of sinusoidal walls are corrected via layer shifting, resulting in accurate control of their geometry and mechanical properties. Furthermore, more substantial layer shifting allows stacking of fiber layers in a horizontal manner, overcoming the electrostatic autofocusing effect that favors vertical layer stacking. Novel nonlinear geometries, such as overhangs, wall texturing and branching, and smooth and abrupt changes in printing trajectory are presented, demonstrating the flexibility of the layer shifting approach beyond the state‐of‐the‐art. The practice of microscale layer shifting for melt electrowriting enables more complex geometries that promise to have a profound impact on the development of products in a broad range of applications.