Fringe Projection Profilometry in Production Metrology: A Multi-Scale Comparison in Sheet-Bulk Metal Forming

Abstract

Fringe projection profilometry in combination with other optical measuring technologies has established itself over the last decades as an essential complement to conventional, tactile measuring devices. The non-contact, holistic reconstruction of complex geometries within fractions of a second in conjunction with the lightweight and transportable sensor design open up many fields of application in production metrology. Furthermore, triangulation-based measuring principles feature good scalability, which has led to 3D scanners for various scale ranges. Innovative and modern production processes, such as sheet-bulk metal forming, thus, utilize fringe projection profilometry in many respects to monitor the process, quantify possible wear and improve production technology. Therefore, it is essential to identify the appropriate 3D scanner for each application and to properly evaluate the acquired data. Through precise knowledge of the measurement volume and the relative uncertainty with respect to the specimen and scanner position, adapted measurement strategies and integrated production concepts can be realized. Although there are extensive industrial standards and guidelines for the quantification of sensor performance, evaluation and tolerancing is mainly global and can, therefore, neither provide assistance in the correct, application-specific positioning and alignment of the sensor nor reflect the local characteristics within the measuring volume. Therefore, this article compares fringe projection systems across various scale ranges by positioning and scanning a calibrated sphere in a high resolution grid.

Creepage Distance Estimation of Hairpin Stators Using 3D Feature Extraction

“…As a result, the data are epresented as a meshed 3D point cloud and stored in .STL-files. For a more detailed overview on the application of fringe projection metrology at various scales within production metrology, a comprehensive assessment is provided in [14].Within the scope of this study, different types of hairpin stators were inspected and reconstructed. The dimensions as well as specifications in terms of the power differentiated depending on the stator type.…”

“…Previous research analysed the performance and revealed the advantages of optical 3D metrology in different applications [14,24,25], and active vision sensors using an additional light source are particularly widespread due to improved robustness and accuracy [26]. Therefore, the development of 3D processing and spatial feature extraction algorithms is crucial.…”

“…The inspection with tactile measurement devices is limited due to the geometry of the hairpin stators. With the advantages of a short inspection time and an increasing resolution in 3D reconstruction, optical measurement systems based on fringe projection profilometry are becoming widely used for inspection applications in production technology [14] and are also used in the proposed approach. Within this study, a novel method is presented in order to estimate the creepage distance based on meshed 3D data.…”

Pose Estimation and Damage Characterization of Turbine Blades during Inspection Cycles and Component-Protective Disassembly Processes

“…Due to the small blade root and the small depth difference of the plastic deformation, most industrial fringe projection sensors are not particularly suitable for this application. Many of these have a larger measuring volume, resulting in a low axial and lateral resolution related to this application [ 40 ]. Due to the smaller measuring volume, the borescopic sensor is applied here; however, other fringe projection sensors can also be used, considering the limitations with regard to resolution and measuring volume.…”

Correlating Ultrasonic Velocity in DC04 with Microstructure for Quantification of Ductile Damage

“…A major challenge in the validation of these models is the detection of the voids. In contrast to defects close to the surface, which can be detected by imaging methods such as visual inspection, microscopy or fringe projection profilometry [10], the voids are located inside the component. One possibility for determining a void volume fraction is using computer tomography (CT).…”